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Theme 1- Does your BioArea belong to a biodiversity hotspot area? are there areas under protection ?

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Theme 1- Does your BioArea belong to a biodiversity hotspot area? are there areas under protection ?

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Belgium has three main geographical regions; the coastal plain in the northwest and the central plateau both belong to the Anglo-Belgian Basin, and the Ardennes uplands in the southeast.
The Flemish Region occupies the northern part of Belgium and covers an area of 13,522 km2 (44.29% of Belgium).
No volcanoes or mountains.

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Area terrestrial: 23%
Area marine: 37%

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Protected Planet is the online interface for the World Database on Protected Areas (WDPA), and the most comprehensive global database on terrestrial and marine protected areas.

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Ecotopes that are very sensitive to a certain environmental pressure and, moreover, are of great biological value, are very vulnerable. Via the link with the Biological Valuation Map the vulnerability of ecotopes for the three environmental pressures is spatially situated. The method is therefore suitable for the environmental assessment of location alternatives.

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This story map was created with the Story Map Series application in ArcGIS Online.

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http://www.biodiv.be/implementation/docs/books/bib/

Research in 2003 estimates the number of species in Belgiumbetween 40,000 and 50,000. Approximately 80% of the species are found in Flanders (Dutch speaking part of Belgium).

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Interesting checklist and Belgium has apparently some endemics... some are cave species. But: post from Isa: https://padlet.com/isa_vandevelde): "when more research will be done in e.g. caves possibility exists that the species could be found outside Belgium as well."

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Wikipedia), is apparently extinct in the wild, but has been successfully germinated at Kew's Royal Botanic Gardens (BBC). Among the invertebrate species described from Belgium and not known from elsewhere are a cave-dwelling rove beetle Tychobythinus belgicus (p. 4 ofCWEPSS pdf file), a parasitic wasp Cleruchus raignieri (p.

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Bromus bromoideus had been thought extinct until  seeds of the plant were discovered in the Meise National Botanic Gardens of Belgium.
From the species seedlings have been planted at a secret spot.in Belgium.

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There are currently 36 recognized biodiversity hotspots. To qualify as a biodiversity hotspot, an area must meet two strict criteria (cfr. Myer's criteria). And Belgium is not one of them but has sites that have a very rich and remarkable biodiversity.

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Spatial developments should pass the biodiversity test.

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IMPACT ON BIODIVERSITY: In Belgium, 25 to 75% of the species risk decreasing very strongly. There are many causes for this, such as the degradation of their habitats by fragmentation, development, soil pollution, water and air, etc. Climate changes further put pressure on biodiversity: the indigenous species have the choice between adapting or migrate and ... extinction. Meanwhile, new species appear that sometimes develop en masse and at the expense of the indigenous species.

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In ons land loopt 25 à 75 % van de soorten het risico zeer sterk in aantal af te nemen. Daarvoor zijn veel oorzaken verantwoordelijk, zoals de aantasting van hun leefgebieden door versnippering, bebouwing, de vervuiling van de bodem, het water en de lucht, enz.

De klimaatveranderingen zetten de biodiversiteit verder onder druk: de inheemse soorten hebben de keuze tussen zich aanpassen of migreren en... uitsterven. Intussen verschijnen er nieuwe soorten die zich soms massaal en ten koste van de inheemse soorten ontwikkelen.

Sinds 2004 is er een alarmerende achteruitgang vastgesteld van het tweestippelig lieveheersbeestje. Dit is te wijten aan de introducie, in de jaren 90, van het Aziatische lieveheersbeestje als biologisch bestrijdingsmiddel. Deze soort voedt zich wel degelijk met bladluizen maar valt ook onze inheemse lieveheersbeestjes aan en eet hun nakomelingen. (Bron: BelgaImage)

Veranderende interacties tussen soorten

Door de stijging van de temperatuur doen bepaalde voorjaarsverschijnselen zich vroeger voor, zoals het ontluiken van de bloemknoppen (5 tot 15 dagen vroeger dan 50 jaar geleden), en bepaalde najaarsverschijnselen later, zoals de verkleuring van de bladeren. Die fenologische veranderingen verstoren de interacties tussen de soorten.

Neem bijvoorbeeld de bonte vliegenvanger. De aankomstdatum van deze trekvogel evolueert trager dan de periode waarin het voornaamste voedsel voor zijn jongen (de beukenrups) voorkomt. De laatste 20 jaar is de vliegenvanger steeds vroeger teruggekomen van zijn overwinteringsgebieden in Afrika, maar niet vroeg genoeg om van de voedselpiek te kunnen profiteren. Het gevolg is dat de populatie bonte vliegenvangers sterk begint terug te lopen in België.

(Bron: BelgaImage)

Sommige soorten vestigen zich in onze streken

De wetenschappers zien ook veranderingen in de verspreidingsgebieden door het feit dat veel thermofiele (warmteminnende) soorten naar het noorden verhuizen. De laatste decennia zijn in België namelijk steeds meer soorten verschenen die in warme gematigde klimaten thuishoren: zuidelijke libellen (zoals de vuurlibel), spinnen (wespspin, afkomstig uit het Middellandse-Zeebekken), vogels (Europese bijeneter, een soort uit het zuiden die tegenwoordig ook in België broedt) en muggen (die tropische ziekten zoals het West-Nijlvirus kunnen overbrengen), enz. Sommige schadelijke soorten hebben voordeel van de effecten van de klimaatverandering (verspreiding van teken, processierupsen, enz.).

In Wallonië heeft men door de opeenvolging van warme en droge zomers gedurende meerdere jaren zeven zuiderse soorten libellen steeds vaker kunnen waarnemen. Hetzelfde geldt voor andere zuiderse insectensoorten zoals sprinkhanen, krekels, vlinders enz.

Deze grafiek toont de evolutie van de observatiefrequentie in Wallonië en Brussel van de 7 soorten die het grondgebied het meest hebben gekoloniseerd in de jaren '80 en '90. De groene lijn geeft de gemiddelde jaartemperatuur door de jaren heen weer. (Bron: Libellenwerkgroep Gomphus Wallonië-Brussel - 2009)

Spinnenonderzoek in de Antwerpse binnenstad door de gebroeders Van Keer heeft aangetoond dat er momenteel een aantal soorten voorkomen, zoals de witrugzakspin, die oorspronkelijk een meer zuiderse verspreiding kenden. Alles wijst erop dat ze op eigen kracht naar Antwerpen afgezakt zijn, en er overleven. Bovendien werden er buitenshuis ook soorten aangetroffen die bij ons normaal gezien alleen binnenshuis voorkomen. Dit alles wijst volgens de arachnologen (spinnenspecialisten) duidelijk op een geleidelijke opwarming van het klimaat."

In de Noordzee veroveren meer zuiderse soorten zoals de sardien en de ansjovis een plaats omdat de temperatuur van het water is gestegen.

... en andere soorten trekken weg

Bepaalde inheemse soorten verlaten onze streken, zoals bijvoorbeeld de kabeljauw, die naar het noorden trekt op zoek naar kouder water.

Bij talrijke andere soorten overstijgt het tempo van de klimaatverandering hun migratiecapaciteit, vooral wanneer hun bewegingen beperkt worden door het versnipperde landschap of wanneer de soorten geen aangepaste habitats kunnen vinden. Sommige vogelsoorten (zoals de keep of de barmsijs) dreigen in de toekomst uit Vlaanderen te verdwijnen, als gevolg van de toegenomen temperatuur tijdens de voortplantingsperiode.

Het Brussels Hoofdstedelijk Gewest heeft in het Zoniënwoud een onderzoek verricht om de invloed van klimaatveranderingen op verschillende bossoorten te evalueren. Dit onderzoek heeft aangetoond dat de verwachte milieuomstandigheden in de toekomst niet gunstig zullen zijn voor de groei van de beuken. De beroemde "beukenkathedraal" is dus in gevaar en zou wel eens voorgoed kunnen verdwijnen.

Meer info :

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In ons land loopt 25 à 75% van de soorten het risico zeer sterk in aantal af te nemen. Daarvoor zijn veel oorzaken verantwoordelijk, zoals de aantasting van hun leefgebieden door versnippering, bebouwing, de vervuiling van de bodem, het water en de lucht, enz.

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I read this from a post https://padlet.com/isa_vandevelde/raiduitjkial  :

But this is important for Belgium:
"Hotspots for biodiversity in the North Sea rediscovered"

Belgian biologists have rediscovered a hotspot for underwater life in the North Sea. In the vicinity of a few sandbanks along the Belgian coast, the fauna is flourishing just like it was a hundred years ago. Despite increased disruption due to fishing, the area is teeming with whelks, top shells and dead man’s fingers.

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Hotspot for Biodiversity in the North Sea Rediscovered | Royal Belgian Institute of Natural Sciences

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Over subsequent decades, the gravel areas were greatly diminished due to fishing: the stones were overturned or pulled up along with the catch, which meant the species that were typical of the region could no longer live there.

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Urban environment needs special attention

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Urban environment needs special attention

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Extreme summers even accelerate the impact of exotic species, especially in cities.

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natuur nieuws actueel natuurberichten natuurnieuws planten klimaat tellen zomer stad beken/sloten/oevers rivieren zeldzame soort nieuwe soort droogte weersinvloeden

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Nature Today | Extreme zomers versnellen inburgering

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De laatste decennia worden er in ons land steeds meer planten uit warmere klimaatgebieden waargenomen. Aanvankelijk is het voorkomen onbestendig en blijft het onduidelijk in hoeverre deze soorten ingeburgerd zijn. Uit verspreidingsgegevens is af te leiden dat extreem warme en droge zomers de inburgering van sommige warmteminnende soorten aanzienlijk kunnen versnellen.

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1 in 10 plants is exotic in Flanders. The proportion of exotic plant species has doubled since the 1970s: from about 5% to about 10%.

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De toename van internationaal transport zorgt voor een permanente aanvoer van nieuwe plantensoorten. Een deel daarvan slaagt erin zich te vestigen en breidt zich spontaan uit. Het ontsnappen van planten uit de horticultuur (bijvoorbeeld via het storten van tuinafval) vormt één van de belangrijkste introductiewegen voor uitheemse planten.

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15% of the total surface in Flanders  is hardened. Impervious pavements deprive tree roots of aeration, eliminating the "urban forest".

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Ruim 15% van totale oppervlakte verhard

In 2021 was 15,3% (207.400 hectare (ha)) van de totale oppervlakte van het Vlaamse Gewest afgedekt of verhard. Die afdekking bestaat vooral uit gebouwen, wegen en parkeerterreinen. In 2013 nam de verharding 14,2% (192.570 ha) in beslag. Tussen 2013 en 2021 kwam er 14.830 ha verharding bij.

Door de afdichting van bodems of het plaatsen van verhardingen die de bodem tot op zekere hoogte ondoordringbaar maken, kunnen de functies van de bodem niet of onvoldoende vervuld worden. De bodem is bijvoorbeeld niet in staat om water op te nemen. Deze verminderde infiltratiecapaciteit zorgt voor een versnelde afvoer van water, met mogelijk overstromingen op aanpalende percelen tot gevolg. Bovendien wordt de waterbalans verstoord en worden grondwatervoorraden niet aangevuld.

Verhardingsgraad hoogst in en rond grootsteden

Van de 300 gemeenten in het Vlaamse Gewest hebben 134 een verhardingsgraad boven het Vlaamse gemiddelde van 15,3%. Het percentage verharding is het hoogst in de gemeenten in de Brusselse en Antwerpse rand en in Antwerpen en Gent. Ook gemeenten zoals Kuurne, Oostende en Waregem vertonen een verhardingsgraad van meer dan 34%. Maar ook meer randstedelijke en landelijke gemeenten, zoals ten noorden van Hasselt, zijn relatief sterk verhard.

ZOEKEN OP STATISTIEK VLAANDEREN

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Ruim 15% van totale oppervlakte verhard Verhardingsgraad hoogst in en rond grootsteden ZOEKEN OP STATISTIEK VLAANDEREN

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My special place in Belgium: Doode Bemde

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My special place in Belgium: Doode Bemde

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Situated in the central part of Belgium, 8 km south of Leuven (Flanders), in the valley of the middle course of the river Dijle. The valley contains a lot of wetland areas, which periodically flood due to the regime in the river. The entire valley of the Dijle is greatly influenced by groundwater seepage. Because the Doode Bemde nature reserve wetlands are predominantly fed by discharging groundwater they are mainly characterized by specific vegetation, which are plant species that occur exclusively in or are limited to the sphere of influence of the groundwater table.

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Learn about and visualise the protected area Doode Bemde (Certified Nature Reserve (Flemish Region)), situated in Belgium

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springtime....

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Vanuit het centrum van Neerijse wandel je langs het domein van het Kasteel van Neerijse het natuurgebied de Doode Bemde in. Dit is een van het grootste (250 ha) en meest waardevolle natuurgebied van de hele Dijlevallei.

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I used  the Red Lists for Flanders for this item and searched if there were any species of "the Doode Bemde" on the list. See some of my results below this item.

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I used  the Red Lists for Flanders for this item and searched if there were any species of "the Doode Bemde" on the list. See some of my results below this item.

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Nederlandse versie In the table below you can search the Red Lists for Flanders:

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Endangered

Half parasite that parasites on the roots of grasses and cyper grasses. The species grows in hay meadows on wet, moderately nutrient-rich to nutrient-poor area. Dewatering and fertilization of the sites are the main reasons for the decline of the species. The cessation of hay management also leads to the disappearance of populations. But in Doode Bemde there is still a population.

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Moeraskartelblad is een een- tot tweejarige halfparasiet die parasiteert op de wortels van grassen en cypergrassen. De soort groeit in hooilanden op natte, matig voedselrijke tot voedselarme, dikwijls venige bodems. De huidige vindplaatsen betreffen vooral dottergraslanden, maar de soort werd vroeger ook in blauwgraslanden en kalkrijke moerassen aan de binnenduinrand gevonden.

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Critically endangered

Endangered through the disappearance of suitable habitats and the drying out and dense growth of the remaining marshes. Porzana porzana prefer larger, open marsh areas with a small-scale mosaic of low and open marsh vegetation in combination with more rugged vegetation and shallow open water. The Flemish government introduced a protection program for this species (and the habitat).

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Porseleinhoen | Agentschap voor Natuur en Bos

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Het porseleinhoen is altijd een vrij zeldzame broedvogel geweest in Vlaanderen maar de populatie ging de laatste decennia sterk achteruit. Waar halverwege de 20ste eeuw de Vlaamse populatie nog op enkele honderden broedparen werd geschat, komen nu jaarlijks nog slechts een handvol koppels tot broeden.

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Vulnerable

The trend is one of decline, until elms are able to develop a natural immunity to the fungal disease, or until very substantial numbers of disease-resistant strains of elm are established. Of all surveyed locations in the province of Flemish-Brabant in 2011, in total 76% appeared affected to a greater or lesser extent due to the elm disease (caused by the fungi Ophiostoma ulmi and Ophiostoma novo-ulmi)

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Ability to form dense stands and competitor for native riverbank plants. Prefers nutrient-rich soils along the riverside. With its intolerance to cold weather and rapid death, the species has also been accused of promoting soil erosion.
In Flanders there is a taskforce to combat this alien species.

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Invasive Alien Species in Belgium: Impatiens glandulifera

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Branta canadensis "Grote Canadese Gans" in Dutch

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Branta canadensis "Grote Canadese Gans" in Dutch

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Here's a picture (I took myself).
I read that "the Canada goose populations have grown at a tremendous rate from 1990 onwards and are still increasing in the Southern part of the country. Geese most often breed along small mesotrophic to eutrophic ponds near open habitats with short grass. They are also increasingly found near wooded ponds and on the islands of large rivers. They are especially common in man-made habitats (parks, golf courses, urban and agricultural areas) but are also known to colonise natural wetlands and coastal areas (e.g. Ramsar zones). Canada goose is primarily a grazer and mainly feeds on grasses and aquatic plants. It takes also advantage of food provided by people in urban areas."
Source: the Belgian Forum on Invasive Species

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Invasive species control in Flanders: hunting and egg destruction

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Invasive species control in Flanders: hunting and egg destruction

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Ardea alba - Great Egret "Grote zilverreiger" 

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Ardea alba - Great Egret "Grote zilverreiger" 

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.A hundred years ago they were hunted a lot for their decorative feathers. Now they are returning in Flanders. (But they don't breed in Flanders.) I learned this fact during a course from Natuurpunt.

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Een betere bescherming van de Grote zilverreiger in de broedgebieden en het geleidelijk verhogen van het waterpeil in diezelfde gebieden blijken succesrijke maatregelen te zijn voor de uitbreiding van deze soort. Als men de soort ook in Vlaanderen in potentiële broedgebieden wil zien verschijnen zal men grote, natte gebieden moeten creëren met overjarig rietland, in combinatie met ondiep, helder en visrijk water.

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The Eurasian beaver (Castor fiber) was nearly hunted to extinction in Europe, both for fur and for castoreum, a secretion from its scent gland believed to have medicinal properties. However, the beaver is now being re-introduced throughout Europe.

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Beavers (genus Castor) are large, semiaquatic rodents of the Northern Hemisphere. There are two existing species: the North American beaver ( Castor canadensis) and the Eurasian beaver ( C. fiber). Beavers are the second-largest living rodents, after capybaras, weighing up to 50 kg (110 lb). They have stout bodies with large heads, long chisel-like incisors, brown or gray fur, hand-like front feet, webbed back feet, and tails that are flat and scaly. The two species differ in skull and tail shape and fur color. Beavers can be found in a number of freshwater habitats, such as rivers, streams, lakes and ponds. They are herbivorous, consuming tree bark, aquatic plants, grasses and sedges.

Beavers build dams and lodges using tree branches, vegetation, rocks and mud; they chew down trees for building material. Dams restrict water flow, and lodges serve as shelters. Their infrastructure creates wetlands used by many other species, and because of their effect on other organisms in the ecosystem, beavers are considered a keystone species. Adult males and females live in monogamous pairs with their offspring. After their first year, the young help their parents repair dams and lodges; older siblings may also help raise newly-born offspring. Beavers hold territories and mark them using scent mounds made of mud, debris, and castoreum-a liquid substance excreted through the beaver's urethra-based castor sacs. Beavers can also recognize their kin by their anal gland secretions and are more likely to tolerate them as neighbors.

Historically, beavers have been hunted for their fur, meat, and castoreum. Castoreum has been used in medicine, perfume, and food flavoring; beaver pelts have been a major driver of the fur trade. Before protections began in the 19th and early 20th centuries, overhunting had nearly exterminated both species. Their populations have since rebounded, and they are listed as species of least concern by the IUCN Red List of mammals. In human culture, the beaver symbolizes industriousness, especially in connection with construction; it is the national animal of Canada.

There are two extant species: the North American beaver ( Castor canadensis) and the Eurasian beaver ( C. fiber). The Eurasian beaver is slightly longer and has a more lengthened skull, triangular nasal cavities (as opposed to the square ones of the North American species), a lighter fur color, and a narrower tail.

Carl Linnaeus coined the genus Castor in 1758; he also coined the specific (species) epithet fiber. German zoologist Heinrich Kuhl coined C. canadensis in 1820. However, they were not confirmed to be separate species until the 1970s, when chromosomal evidence became available. (The Eurasian has 48 chromosomes, while the North American has 40.) Prior to that, many considered them the same species. The difference in chromosome numbers prevents them from interbreeding. Twenty-five subspecies have been classified for C. canadensis, and nine have been classified for C. fiber.

Phylogeny of extant and extinct relatives of modern beavers based on genetics and morphology.

Beavers belong to the rodent suborder Castorimorpha, along with Heteromyidae ( kangaroo rats and kangaroo mice), and the gophers. Modern beavers are the only extant members of the family Castoridae. They originated in North America in the late Eocene and colonized Eurasia via the Bering Land Bridge in the early Oligocene, coinciding with the Grande Coupure, a time of significant changes in animal species around 33million years ago ( myr).

The more basal castorids had several unique features: more complex occlusion between cheek teeth, parallel rows of upper teeth, premolars that were only slightly smaller than molars, the presence of a third set of premolars (P3), a hole in the stapes of the inner ear, a smooth palatine bone (with the palatine opening closer to the rear end of the bone), and a longer snout. More derived castorids have less complex occlusion, upper tooth rows that create a V-shape towards the back, larger second premolars compared to molars, absence of a third premolar set and stapes hole, a more grooved palatine (with the opening shifted towards the front), and reduced incisive foramen. Members of the subfamily Palaeocastorinae appeared in late-Oligocene North America. This group consisted primarily of smaller animals with relatively large front legs, a flattened skull, and a reduced tail-all features of a fossorial (burrowing) lifestyle.

In the early Miocene (about 24 mya), castorids evolved a semiaquatic lifestyle. Members of the subfamily Castoroidinae are considered to be a sister group to modern beavers, and included giants like Castoroides of North America and Trogontherium of Eurasia. Castoroides is estimated to have had a length of 1.9-2.2 m (6.2-7.2 ft) and a weight of 90-125 kg (198-276 lb). Fossils of one genus in Castoroidinae, , have been found near piles of chewed wood, though Dipoides appears to have been an inferior woodcutter compared to Castor. Researchers suggest that modern beavers and Castoroidinae shared a bark-eating common ancestor. Dam and lodge-building likely developed from bark-eating, and allowed beavers to survive in the harsh winters of the subarctic. There is no conclusive evidence for this behavior occurring in non- Castor species.

The genus Castor likely originated in Eurasia. The earliest fossil remains appear to be C. neglectus, found in Germany and dated 12-10 mya. Mitochondrial DNA studies place the common ancestor of the two living species at around 8 mya. The ancestors of the North American beaver would have crossed the Bering Land Bridge around 7.5 mya. Castor may have competed with members of Castoroidinae, which led to niche differentiation. The fossil species C. praefiber was likely an ancestor of the Eurasian beaver. C. californicus from the Early Pleistocene of North America was similar to but larger than the extant North American beaver.

Characteristics

Beavers are the second-largest living rodents, after capybaras. They have a head-body length of 80-120 cm (31-47 in), with a 25-50 cm (9.8-19.7 in) tail, a shoulder height of 30-60 cm (12-24 in), and generally weigh 11-30 kg (24-66 lb), but can be as heavy as 50 kg (110 lb). Males and females are almost identical externally. Their bodies are streamlined like marine mammals and their robust build allows them to pull heavy loads. A beaver coat has 12,000-23,000 hairs/cm ² (77,000-148,000 hairs/in ²) and functions to keep the animal warm, to help it float in water, and to protect it against predators. Guard hairs are 5-6 cm (2.0-2.4 in) long and typically reddish brown, but can range from yellowish brown to nearly black. The underfur is 2-3 cm (0.79-1.18 in) long and dark gray. Beavers molt every summer.

Beavers have large skulls with powerful chewing muscles. They have four chisel-shaped incisors that continue to grow throughout their lives. The incisors are covered in a thick enamel that is colored orange or reddish-brown by iron compounds. The lower incisors have roots that are almost as long as the entire lower jaw. Beavers have one premolar and three molars on all four sides of the jaws, adding up to 20 teeth. The molars have meandering ridges for grinding woody material. The eyes, ears and nostrils are arranged so that they can remain above water while the rest of the body is submerged. The nostrils and ears have valves that close underwater, while nictitating membranes cover the eyes. To protect the larynx and trachea from water flow, the epiglottis is contained within the nasal cavity instead of the throat. In addition, the back of the tongue can rise and create a waterproof seal. A beaver's lips can close behind the incisors, preventing water from entering their mouths as they cut and bite onto things while submerged.

The beaver's front feet are dexterous, allowing them to grasp and manipulate objects and food, as well as dig. The hind feet are larger and have webbing between the toes, and the second innermost toe has a "double nail" used for grooming. Beavers can swim at 8 km/h (5.0 mph); only their webbed hind feet are used to swim, while the front feet fold under the chest. On the surface, the hind limbs thrust one after the other; while underwater, they move at the same time. Beavers are awkward on land but can move quickly when they feel threatened. They can carry objects while walking on their hind legs.

The beaver's distinctive tail has a conical, muscular, hairy base; the remaining two-thirds of the appendage is flat and scaly. The tail has multiple functions: it provides support for the animal when it is upright (such as when chewing down a tree), acts as a rudder when it is swimming, and stores fat for winter. It also has a countercurrent blood vessel system which allows the animal to lose heat in warm temperatures and retain heat in cold temperatures.

The beaver's sex organs are inside the body, and the male's penis has a cartilaginous baculum. They have only one opening, a cloaca, which is used for reproduction, scent-marking, defecation, and urination. The cloaca evolved secondarily, as most mammals have lost this feature, and may reduce the area vulnerable to infection in dirty water. The beaver's intestine is six times longer than its body, and the caecum is double the volume of its stomach. Microorganisms in the caecum allow them to process around 30 percent of the cellulose they eat. A beaver defecates in the water, leaving behind balls of sawdust. Female beavers have four mammary glands; these produce milk with 19 percent fat, a higher fat content than other rodents. Beavers have two pairs of glands: castor sacs, which are part of the urethra, and anal glands. The castor sacs secrete castoreum, a liquid substance used mainly for marking territory. Anal glands produce an oily substance which the beaver uses as a waterproof ointment for its coat. The substance plays a role in individual and family recognition. Anal secretions are darker in females than males among Eurasian beavers, while the reverse is true for the North American species.

Compared to many other rodents, a beaver's brain has a hypothalamus that is much smaller than the cerebrum; this indicates a relatively advanced brain with higher intelligence. The cerebellum is large, allowing the animal to move within a three-dimensional space (such as underwater) similar to tree-climbing squirrels. The neocortex is devoted mainly to touch and hearing. Touch is more advanced in the lips and hands than the whiskers and tail. Vision in the beaver is relatively poor; the beaver eye cannot see as well underwater as an otter. Beavers have a good sense of smell, which they use for detecting land predators and for inspecting scent marks, food, and other individuals.

Beavers can hold their breath for as long as 15 minutes but typically remain underwater for no more than five or six minutes. Dives typically last less than 30 seconds and are usually no more than 1 m (3 ft 3 in) deep. When diving, their heart rate decreases to 60 beats per minute, half its normal pace, and blood flow is directed more towards the brain. A beaver's body also has a high tolerance for carbon dioxide. When surfacing, the animal can replace 75 percent of the air in its lungs in one breath, compared to 15 percent for a human.

Distribution and status

North American beaver in Yellowstone National Park

The IUCN Red List of mammals lists both beaver species as least concern. The North American beaver is widespread throughout most of the United States and Canada and can be found in northern Mexico. The species was introduced to Finland in 1937 (and then spread to northwestern Russia) and to Tierra del Fuego, Patagonia, in 1946. As of 2019, the introduced population of North American beavers in Finland has been moving closer to the habitat of the Eurasian beaver. Historically, the North American beaver was trapped and nearly extirpated because its fur was highly sought after. Protections have allowed the beaver population on the continent to rebound to an estimated 6-12million by the late 20th century; still far lower than the originally estimated 60-400million North American beavers before the fur trade. The introduced population in Tierra del Fuego is estimated at 35,000-50,000 individuals as of 2016.

The Eurasian beaver's range historically included much of Eurasia, but was decimated by hunting by the early 20th century. In Europe, beavers were reduced to fragmented populations, with combined population numbers being estimated at 1,200 individuals for the Rhône of France, the Elbe in Germany, southern Norway, the Neman river and Dnieper Basin in Belarus, and the Voronezh river in Russia. The beaver has since recolonized parts of its former range, aided by conservation policies and reintroductions. Beaver populations now range across western, central, and eastern Europe, and western Russia and the Scandinavian Peninsula. Beginning in 2009, beavers have been successfully reintroduced to parts of Great Britain. In 2020, the total Eurasian beaver population in Europe was estimated at over one million. Small native populations are also present in Mongolia and northwestern China; their numbers were estimated at 150 and 700, respectively, as of 2016. Under New Zealand's Hazardous Substances and New Organisms Act 1996, beavers are classed as a "prohibited new organism" preventing them from being introduced into the country.

Eurasian beavers swimming and foraging

Beavers live in freshwater ecosystems such as rivers, streams, lakes and ponds. Water is the most important part of beaver habitat; they swim and dive in it, and it provides them a refuge from land predators, restricts access to their homes and allows them to move building objects more easily. Beavers prefer slower moving streams, typically with a gradient (steepness) of one percent, though they have been recorded using streams with gradients as high as 15 percent. Beavers are found in wider streams more often than in narrower ones. They also prefer areas with no regular flooding and may abandon a location for years after a significant flood.

Beavers typically select flat landscapes with diverse vegetation close to the water. North American beavers prefer trees being 60 m (200 ft) or less from the water, but will roam several hundred meters to find more. Beavers have also been recorded in mountainous areas. Dispersing beavers will use certain habitats temporarily before finding their ideal home. These include small streams, temporary swamps, ditches, and backyards. These sites lack important resources, so the animals do not stay there permanently. Beavers have increasingly settled at or near human-made environments, including agricultural areas, suburbs, golf courses, and shopping malls.

Beavers have an herbivorous and a generalist diet. During the spring and summer, they mainly feed on herbaceous plant material such as leaves, roots, herbs, ferns, grasses, sedges, water lilies, water shields, rushes, and cattails. During the fall and winter, they eat more bark and cambium of woody plants; tree and shrub species consumed include aspen, birch, oak, dogwood, willow and alder. There is some disagreement about why beavers select specific woody plants; some research has shown that beavers more frequently select species which are more easily digested, while others suggest beavers principally forage based on stem size. Beavers may cache their food for the winter, piling wood in the deepest part of their pond where it cannot be reached by other browsers. This cache is known as a "raft"; when the top becomes frozen, it creates a "cap". The beaver accesses the raft by swimming under the ice. Many populations of Eurasian beaver do not make rafts, but forage on land during winter.

Beavers usually live up to 10 years. Felids, canids, and bears may prey upon them. Beavers are protected from predators when in their lodges, and prefer to stay near water. Parasites of the beaver include the bacteria Francisella tularensis, which causes tularemia; the protozoan Giardia duodenalis, which causes giardiasis (beaver fever); and the beaver beetle and mites of the genus Schizocarpus. They have also been recorded to be infected with the rabies virus.

Infrastructure

Beavers need trees and shrubs to use as building material for dams, which restrict flowing water to create a pond for them to live in, and for lodges, which act as shelters and refuges from predators and the elements. Without such material, beavers dig burrows into a bank to live. Dam construction begins in late summer or early fall, and they repair them whenever needed. Beavers can cut down trees up to 15 cm (5.9 in) wide in less than 50 minutes. Thicker trees, at 25 cm (9.8 in) wide or more, may not fall for hours. When chewing down a tree, beavers switch between biting with the left and right side of the mouth. Tree branches are then cut and carried to their destination with the powerful jaw and neck muscles. Other building materials, like mud and rocks, are held by the forelimbs and tucked between the chin and chest.

Beaver start building dams when they hear running water, and the sound of a leak in a dam triggers them to repair it. To build a dam, beavers stack up relatively long and thick logs between banks and in opposite directions. Heavy rocks keep them stable, and grass is packed between them. Beavers continue to pile on more material until the dam slopes in a direction facing upstream. Dams can range in height from 20 cm (7.9 in) to 3 m (9.8 ft) and can stretch from 0.3 m (1 ft 0 in) to several hundred meters long. Beaver dams are more effective in trapping and slowly leaking water than man-made concrete dams. Lake-dwelling beavers do not need to build dams.

Beavers make two types of lodges: bank lodges and open-water lodges. Bank lodges are burrows dug along the shore and covered in sticks. The more complex freestanding, open-water lodges are built over a platform of piled-up sticks. The lodge is mostly sealed with mud, except for a hole at the top which acts as an air vent. Both types are accessed by underwater entrances. The above-water space inside the lodge is known as the "living chamber", and a "dining area" may exist close to the water entrance. Families routinely clean out old plant material and bring in new material.

North American beavers build more open-water lodges than Eurasian beavers. Beaver lodges built by new settlers are typically small and sloppy. More experienced families can build structures with a height of 2 m (6 ft 7 in) and an above-water diameter of 6 m (20 ft). A lodge sturdy enough to withstand the coming winter can be finished in just two nights. Both lodge types can be present at a beaver site. During the summer, beavers tend to use bank lodges to keep cool. They use open-water lodges during the winter. The air vent provides ventilation, and newly-added carbon dioxide can be cleared in an hour. The lodge remains consistent in oxygen and carbon dioxide levels from season to season.

Beavers in some areas will dig canals connected to their ponds. The canals fill with groundwater and give beavers access and easier transport of resources, as well as allow them to escape predators. These canals can stretch up to 1 m (3 ft 3 in) wide, 0.5 m (1 ft 8 in) deep, and over 0.5 km (0.31 mi) long. It has been hypothesized that beavers' canals are not only transportation routes but an extension of their " central place" around the lodge and/or food cache. As they drag wood across the land, beavers leave behind trails or "slides", which they reuse when moving new material.

Environmental effects

The beaver works as an ecosystem engineer and keystone species, as its activities can have a great impact on the landscape and biodiversity of an area. Aside from humans, few other extant animals appear to do more to shape their environment. When building dams, beavers alter the paths of streams and rivers, allowing for the creation of extensive wetland habitats. In one study, beavers were associated with large increases in open-water areas. When beavers returned to an area, 160% more open water was available during droughts than in previous years, when they were absent. Beaver dams also lead to higher water tables in mineral soil environments and in wetlands such as peatlands. In peatlands particularly, their dams stabilize the constantly changing water levels, leading to greater carbon storage.

Beaver ponds, and the wetlands that succeed them, remove sediments and pollutants from waterways, and can stop the loss of important soils. These ponds can increase the productivity of freshwater ecosystems by accumulating nitrogen in sediments. Beaver activity can affect the temperature of the water; in northern latitudes, ice thaws earlier in the warmer beaver-dammed waters. Beavers may contribute to climate change. In Arctic areas, the floods they create can cause permafrost to thaw, releasing methane into the atmosphere.

As wetlands are formed and riparian habitats are enlarged, aquatic plants colonize the newly-available watery habitat. One study in the Adirondacks found that beaver engineering lead to an increase of more than 33 percent in herbaceous plant diversity along the water's edge. Another study in semiarid eastern Oregon found that the width of riparian vegetation on stream banks increased several-fold as beaver dams watered previously dry terraces adjacent to the stream. Riparian ecosystems in arid areas appear to sustain more plant life when beaver dams are present. Beaver ponds act as a refuge for riverbank plants during wildfires, and provide them with enough moisture to resist such fires. Introduced beavers at Tierra del Fuego have been responsible for destroying the indigenous forest. Unlike trees in North America, many trees in South America cannot grow back after being cut down.

Salmon (Oncorhynchus nerka) jumping a beaver dam

Beaver activity impacts communities of aquatic invertebrates. Damming typically leads to an increase of slow or motionless water species, like dragonflies, oligochaetes, snails, and mussels. This is to the detriment of rapid water species like black flies, stoneflies, and net-spinning caddisflies. Beaver floodings create more dead trees, providing more habitat for terrestrial invertebrates like Drosophila flies and bark beetles, which live and breed in dead wood. The presence of beavers can increase wild salmon and trout populations, and the average size of these fishes. These species use beaver habitats for spawning, overwintering, feeding, and as havens from changes in water flow. The positive effects of beaver dams on fish appear to outweigh the negative effects, such as blocking of migration. Beaver ponds have been shown to be beneficial to frog populations by protecting areas for larvae to mature in warm water. The stable waters of beaver ponds also provide ideal habitat for freshwater turtles.

Beavers help waterfowl by creating increased areas of water. The widening of the riparian zone associated with beaver dams has been shown to increase the abundance and diversity of birds favoring the water's edge, an impact that may be especially important in semi-arid climates. Fish-eating birds use beaver ponds for foraging, and in some areas, certain species appear more frequently at sites where beavers were active than at sites with no beaver activity. In a study of Wyoming streams and rivers, watercourses with beavers had 75 times as many ducks as those without. As trees are drowned by rising beaver impoundments, they become an ideal habitat for woodpeckers, which carve cavities that may be later used by other bird species. Beaver-caused ice thawing in northern latitudes allows Canada geese to nest earlier.

Other semi-aquatic mammals, such as water voles, muskrats, minks, and otters, will shelter in beaver lodges. Beaver modifications to streams in Poland create habitats favorable to bat species that forage at the water surface and "prefer moderate vegetation clutter". Large herbivores, such as some deer species, benefit from beaver activity as they can access vegetation from fallen trees and ponds.

Beavers are mainly nocturnal and crepuscular, and spend the daytime in their shelters. In northern latitudes, beaver activity is decoupled from the 24-hour cycle during the winter, and may last as long as 29 hours. They do not hibernate during winter, and spend much of their time in their lodges.

Family life

The core of beaver social organization is the family, which is composed of an adult male and an adult female in a monogamous pair and their offspring. Beaver families can have as many as ten members; groups about this size require multiple lodges. Mutual grooming and play fighting maintain bonds between family members, and aggression between them is uncommon.

Adult beavers mate with their partners, though partner replacement appears to be common. A beaver that loses its partner will wait for another one to come by. Estrus cycles begin in late December and peak in mid-January. Females may have two to four estrus cycles per season, each lasting 12-24 hours. The pair typically mate in the water and to a lesser extent in the lodge, for half a minute to three minutes.

Up to four young, or kits, are born in spring and summer, after a three or four-month gestation. Newborn beavers are precocial with a full fur coat, and can open their eyes within days of birth. Their mother is the primary caretaker, while their father maintains the territory. Older siblings from a previous litter also play a role.

After they are born, the kits spend their first one to two months in the lodge. Kits suckle for as long as three months, but can eat solid food within their second week and rely on their parents and older siblings to bring it to them. Eventually, beaver kits explore outside the lodge and forage on their own, but may follow an older relative and hold onto their backs. After their first year, young beavers help their families with construction. Beavers sexually mature around 1.5-3 years. They become independent at two years old, but remain with their parents for an extra year or more during times of food shortage, high population density, or drought.

Territories and spacing

Beavers typically disperse from their parental colonies during the spring or when the winter snow melts. They often travel less than 5 km (3.1 mi), but long-distance dispersals are not uncommon when previous colonizers have already exploited local resources. Beavers are able to travel greater distances when free-flowing water is available. Individuals may meet their mates during the dispersal stage, and the pair travel together. It may take them weeks or months to reach their final destination; longer distances may require several years. Beavers establish and defend territories along the banks of their ponds, which may be 1-7 km (0.62-4.35 mi) in length.

Beavers mark their territories by constructing scent mounds made of mud and vegetation, scented with castoreum. Those with many territorial neighbors create more scent mounds. Scent marking increases in spring, during the dispersal of yearlings, to deter interlopers. Beavers are generally intolerant of intruders and fights may result in deep bites to the sides, rump, and tail. They exhibit a behavior known as the " dear enemy effect"; a territory-holder will investigate and become familiar with the scents of its neighbors and react more aggressively to the scents of strangers passing by. Beavers are also more tolerant of individuals that are their kin. They recognize them by using their keen sense of smell to detect differences in the composition of anal gland secretions. Anal gland secretion profiles are more similar among relatives than unrelated individuals.

Communication

Beavers within a family greet each other with whines. Kits will attract the attention of adults with mews, squeaks, and cries. Defensive beavers produce a hissing growl and gnash their teeth. Tail slaps, which involve an animal hitting the water surface with its tail, serve as alarm signals warning other beavers of a potential threat. An adult's tail slap is more successful in alerting others, who will escape into the lodge or deeper water. Juveniles have not yet learned the proper use of a tail slap, and hence are normally ignored. Eurasian beavers have been recorded using a territorial "stick display", which involves individuals holding up a stick and bouncing in shallow water.

Interactions with humans

Grey Owl feeding his beaver

Beavers sometimes come into conflict with humans over land use; individual beavers may be labeled as "nuisance beavers". Beavers can damage crops, timber stocks, roads, ditches, gardens, and pastures via gnawing, eating, digging, and flooding. They occasionally attack humans and domestic pets, particularly when infected with rabies, in defense of their territory, or when they feel threatened. Some of these attacks have been fatal, including at least one human death. Beavers can spread giardiasis ('beaver fever') by infecting surface waters, though outbreaks are more commonly caused by human activity.

Flow devices, like beaver pipes, are used to manage beaver flooding, while fencing and hardware cloth protect trees and shrubs from beaver damage. If necessary, hand tools, heavy equipment, or explosives are used to remove dams. Hunting, trapping, and relocation may be permitted as forms of population control and for removal of individuals. The governments of Argentina and Chile have authorized the trapping of invasive beavers in hopes of eliminating them. The ecological importance of beavers has led to cities like Seattle designing their parks and green spaces to accommodate the animals. The Martinez beavers became famous in the mid-2000s for their role in improving the ecosystem of Alhambra Creek in Martinez, California.

Zoos have displayed beavers since at least the 19th century, though not commonly. In captivity, beavers have been used for entertainment, fur harvesting, and for reintroduction into the wild. Captive beavers require access to water, substrate for digging, and artificial shelters. Archibald Stansfeld "Grey Owl" Belaney pioneered beaver conservation in the early 20th century. Belaney wrote several books, and was first to professionally film beavers in their environment. In 1931, he moved to a log cabin in Prince Albert National Park, where he was the "caretaker of park animals" and raised a beaver pair and their four offspring.

Commercial use

Beavers have been hunted, trapped, and exploited for their fur, meat, and castoreum. Since the animals typically stayed in one place, trappers could easily find them and could kill entire families in a lodge. Many pre-modern people mistakenly thought that castoreum was produced by the testicles or that the castor sacs of the beaver were its testicles, and females were hermaphrodites. Aesop's Fables describes beavers chewing off their testicles to preserve themselves from hunters, which is impossible because a beaver's testicles are internal. This myth persisted for centuries, and was corrected by French physician Guillaume Rondelet in the 1500s. Beavers have historically been hunted and captured using deadfalls, snares, nets, bows and arrows, spears, clubs, firearms, and leg-hold traps. Castoreum was used to lure the animals.

Castoreum was used for a variety of medical purposes; Pliny the Elder promoted it as a treatment for stomach problems, flatulence, seizures, sciatica, vertigo, and epilepsy. He stated it could stop hiccups when mixed with vinegar, toothaches if mixed with oil (by administering into the ear opening on the same side as the tooth), and could be used as an antivenom. The substance has traditionally been prescribed to treat hysteria in women, which was believed to have been caused by a "toxic" womb. Castoreum's properties have been credited to the accumulation of salicylic acid from willow and aspen trees in the beaver's diet, and has a physiological effect comparable to aspirin. Today, the medical use of castoreum has declined and is limited mainly to homeopathy. The substance is also used as an ingredient in perfumes and tinctures, and as a flavouring in food and drinks.

Various Native American groups have historically hunted beavers for food. Beaver meat was advantageous, being more calorie-rich and fattened than other red meats, and the animals remained plump in winter, when they were most hunted. The bones were used to make tools. In medieval Europe, the Catholic Church considered the beaver to be part mammal and part fish, and allowed followers to eat the scaly, fishlike tail on meatless Fridays during Lent. Beaver tails were thus highly-prized in Europe; they were described by French naturalist Pierre Belon as tasting like a "nicely dressed eel".

Beaver pelts were used to make hats; felters would remove the guard hairs. The number of pelts needed depended on the type of hat, with Cavalier and Puritan hats requiring more fur than top hats. In the late 16th century, Europeans began to deal in North American furs due to the lack of taxes or tariffs on the continent and the decline of fur-bearers at home. Beaver pelts caused or contributed to the Beaver Wars, King William's War, and the French and Indian War; the trade made John Jacob Astor and the owners of the North West Company very wealthy. For Europeans in North America, the fur trade was a driver of the exploration and westward exploration on the continent and contact with native peoples, who traded with them. The fur trade peaked between 1860 and 1870, when over 150,000 beaver pelts were purchased annually by the Hudson's Bay Company and fur companies in the United States. The contemporary global fur trade is not as profitable due to conservation, anti-fur and animal rights campaigns.

Beaver sculpture over entrance to the Canadian Parliament Building

The beaver has been used to represent productivity, trade, tradition, masculinity, and respectability. References to the beaver's skills are reflected in everyday language. The English verb "to beaver" means working with great effort and being "as busy as a beaver"; a "beaver intellect" refers to a way of thinking that is slow and honest. The word "beaver" can also be used as a sexual term for the human vulva.

Native American myths emphasize the beaver's skill and industriousness. In the mythology of the Haida, beavers are descended from the Beaver-Woman, who built a dam on a stream next to their cabin while her husband was out hunting and gave birth to the first beavers. In a Cree story, the Great Beaver and its dam caused a world flood. Other tales involve beavers using their tree chewing skills against an enemy. Beavers have been featured as companions in some stories, including a Lakota tale where a young woman flees from her evil husband with the aid of her pet beaver.

Europeans have traditionally thought of beavers as fantastical animals due to their amphibious nature. They depicted them with exaggerated tusk-like teeth, dog- or pig-like bodies, fish tails, and visible testicles. French cartographer Nicolas de Fer illustrated beavers building a dam at Niagara Falls, fantastically depicting them like human builders. Beavers have also appeared in literature such as Dante Alighieri's Divine Comedy and the writings of Athanasius Kircher, who wrote that on Noah's Ark the beavers were housed near a water-filled tub that was also used by mermaids and otters.

The beaver has long been associated with Canada, appearing on the first pictorial postage stamp issued in the Canadian colonies in 1851 as the so-called " Three-Penny Beaver". It was declared the national animal in 1975. The five-cent coin, the coat of arms of the Hudson's Bay Company, and the logos for Parks Canada and Roots Canada use its image. Frank and Gordon are two fictional beavers that appeared in Bell Canada's advertisements between 2005 and 2008. However, the beaver's status as a rodent has made it controversial, and it was not chosen to be on the Arms of Canada in 1921. The beaver has commonly been used to represent Canada in political cartoons, typically to signify it as a friendly but relatively weak nation. In the United States, the beaver is the state animal of New York and Oregon. It is also featured on the coat of arms of the London School of Economics.

References

1. ^ International Commission on Zoological Nomenclature (1922). "Opinion 75. Twenty-Seven Generic Names of Protozoa, Vermes, Pisces, Reptilia and Mammalia Included in the Official List of Zoological Names". Smithsonian Miscellaneous Collections. 73 (1): 35-37.

2. ^ Busher, P.; Hartman, G. (2001). "Beavers". In MacDonald, D. W. (ed.). The Encyclopedia of Mammals (2nd ed.). Oxford University Press. pp. 590-593. ISBN 978-0760719695.

3. ^ Fabre, Pierre-Henri; Hautier, Lionel; Dimitrov, Dimitar; Douzery, Emmanuel J. P. (2012). "A glimpse on the pattern of rodent diversification: a phylogenetic approach". BMC Evolutionary Biology. 12 (88): 88. doi:10.1186/1471-2148-12-88. PMC . PMID 22697210.

4. ^ Doronina, Liliya; Matzke, Andreas; Churakov, Gennady; Stoll, Monika; Huge, Andreas; Schmitz, Jürgen (2017). "The beaver's phylogenetic lineage illuminated by retroposon reads". Scientific Reports. 7 (1): 43562. Bibcode:2017NatSR...743562D. doi:10.1038/srep43562. PMC . PMID 28256552.

5. ^ Swinehart, A. L.; Richards, R. L. (2001). "Paleoecology of Northeast Indiana Wetland Harboring Remains of the Pleistocene Giant Beaver (Castoroides Ohioensis)". Proceedings of the Indiana Academy of Science. 110: 151.

6. ^ Samuels, J. X.; Zancanella, J. (2011). "An early Hemphillian occurrence of Castor (Castoridae) from the Rattlesnake Formation of Oregon". Journal of Paleontology. 85 (5): 930-935. doi:10.1666/11-016.1. S2CID 128866799.

7. ^ Barisone, G.; Argenti, P.; Kotsakis, T. (2006). "Plio-Pleistocene evolution of the genus Castor (Rodentia, Mammalia) in Europe: C. fiber plicidens of Pietrafitta (Perugia, Central Italy)". . 39 (6): 757-770. Bibcode:2006Geobi..39..757B. doi:10.1016/j.geobios.2005.10.004.

8. ^ Baker, B. W.; Hill, E. P. (2003). "Beaver Castor canadensis". In Feldhamer, G. A.; Thompson, B. C.; Chapman, J. A. (eds.). Wild Mammals of North America: Biology, Management, and Conservation (2 ed.). Johns Hopkins University Press. pp. 289-297. ISBN 978-0801874161. OCLC 51969059.

9. ^ Campbell-Palmer, Róisín; Gow, Derek; Needham, Robert; Jones, Simon; Rosell, Frank (2015). The Eurasian Beaver. Pelagic Publishing Ltd. pp. 7-12. ISBN 978-1784270407.

10. ^ Graf, P. M.; Wilson, R. P.; Sanchez, L. C.; Hacklӓnder, K.; Rosell, F. (2017). "Diving behavior in a free‐living, semi‐aquatic herbivore, the Eurasian beaver Castor fiber". Ecology and Evolution. 8 (2): 997-1008. doi:10.1002/ece3.3726. PMC . PMID 29375773.

11. ^ Naiman, Robert J.; Johnston, Carol A.; Kelley, James C. (December 1988). "Alteration of North American Streams by Beaver" (PDF). BioScience. 38 (11): 753-762. doi:10.2307/1310784. JSTOR 1310784. Archived from the original (PDF) on March 4, 2012.

12. ^ "Beaver reintroduction in the UK". Royal Society for the Protection of Birds. Archived from the original on November 6, 2020.

13. ^ "Hazardous Substances and New Organisms Act 2003 - Schedule 2 Prohibited new organisms". New Zealand Government. Archived from the original on November 6, 2020.

14. ^ Mahoney, Michael J.; Stella, John C. (2020). "Stem size selectivity is stronger than species preferences for beaver, a central place forager". Forest Ecology and Management. 475: 118331. doi:10.1016/j.foreco.2020.118331. S2CID 224922775.

15. ^ Grudzinski, Bartosz P.; Cummins, Hays; Vang, Teng Keng (2019). "Beaver canals and their environmental effects". Progress in Physical Geography: Earth and Environment. 44 (2): 189-211. doi:10.1177/0309133319873116. S2CID 204257682.

16. ^ Rosell F; Bozser O; Collen P; Parker H (2005). "Ecological impact of beavers Castor fiber and Castor canadensis and their ability to modify ecosystems". Mammal Review. 35 (3-4): 248-276. doi:10.1111/j.1365-2907.2005.00067.x. hdl:11250/2438080.

17. ^ Burchsted, D.; Daniels, M.; Thorson, R.; Vokoun, J. (2010). "The river discontinuum: applying beaver modifications to baseline conditions for restoration of forested headwaters". BioScience. 60 (11): 908-922. doi:10.1525/bio.2010.60.11.7. S2CID 10070184.

18. ^ Hood, Glynnis A.; Bayley, Suzanne E. (2008). "Beaver (Castor canadensis) mitigate the effects of climate on the area of open water in boreal wetlands in western Canada". Biological Conservation. 141 (2): 556-567. doi:10.1016/j.biocon.2007.12.003. S2CID 84584842.

19. ^ Puttock, A.; Graham, H. A.; Carless, D.; Brazier, R. E. (2018). "Sediment and Nutrient Storage in a Beaver Engineered Wetland". Earth Surface Processes and Landforms. 43 (11): 2358-2370. Bibcode:2018ESPL...43.2358P. doi:10.1002/esp.4398. PMC . PMID 30333676.

20. Bromley, Chantal K.; Hood, Glynnis A. (2013). "Beavers (Castor canadensis) facilitate early access by Canada geese (Branta canadensis) to nesting habitat and areas of open water in Canada's boreal wetlands". Mammalian Biology. 78 (1): 73-77. doi:10.1016/j.mambio.2012.02.009.

21. ^ Jones, B. M.; Tape, K. D.; Clark, J. A.; Nitze, I.; Grosse, G.; Disbrow, J. (2020). "Increase in beaver dams controls surface water and thermokarst dynamics in an Arctic tundra region, Baldwin Peninsula, northwestern Alaska". Environmental Research Letters. 15 (7): 075005. Bibcode:2020ERL....15g5005J. doi:10.1088/1748-9326/ab80f1.

22. ^ Hunt, Kate (June 30, 2020). "Beavers are gnawing away at the Arctic permafrost, and that's bad for the planet". CNN.

23. ^ Wright, J. P.; Jones, C. G.; Flecker, A. S. (2002). "An ecosystem engineer, the beaver, increases species richness at the landscape scale" (PDF). . 132 (1): 96-101. Bibcode:2002Oecol.132...96W. doi:10.1007/s00442-002-0929-1. PMID 28547281. S2CID 5940275. Archived (PDF) from the original on October 9, 2022.

24. ^ Fairfax, E.; Small, E. E. (2018). "Using remote sensing to assess the impact of beaver damming on riparian evapotranspiration in an arid landscape". Ecohydrology. 11 (7): e1993. doi:10.1002/eco.1993. S2CID 134994160.

25. ^ Fairfax, E; Whittle, A. (2020). "Smokey the Beaver: beaver‐dammed riparian corridors stay green during wildfire throughout the western United States". Ecological Applications. 30 (8): e02225. doi:10.1002/eap.2225. PMID 32881199.

26. ^ Saarenmaa, H. (1978). "The occurrence of bark beetles (Col. Scolytidae) in a dead spruce stand flooded by beavers (Castor canadensis Kuhl)". Silva Fennica: 201-216. doi:10.14214/sf.a14857.

27. ^ Kemp, P. S.; Worthington, T. A.; Langford, T. E. L.; Tree, A. R. J.; Gaywood, M. J. (2012). "Qualitative and quantitative effects of reintroduced beavers on stream fish". Fish and Fisheries. 13 (2): 158-181. doi:10.1111/j.1467-2979.2011.00421.x.

28. ^ Cooke, Hilary A.; Zack, Steve (2008). "Influence of Beaver Dam Density on Riparian Areas and Riparian Birds in Shrubsteepe of Wyoming". Western North American Naturalist. 68 (3): 365-373. doi:10.3398/1527-0904(2008)68[365:IOBDDO]2.0.CO;2. S2CID 62833818.

29. Grover, A. M.; Baldassarre, G. A. (1995). "Bird species richness within beaver ponds in south-central New York". Wetlands. 15 (2): 108-118. doi:10.1007/BF03160664. S2CID 13053029.

30. ^ Nummbi, P.; Holopainen, S. (2014). "Whole-community facilitation by beaver: ecosystem engineer increases waterbird diversity". Aquatic Conservation: Marine and Freshwater Ecosystems. 24 (5): 623-633. doi:10.1002/aqc.2437.

31. ^ Mayer, M; Zedrosser, A; Rosell, F (2017). "When to leave: the timing of natal dispersal in a large, monogamous rodent, the Eurasian beaver". Animal Behaviour. 123: 375-382. doi:10.1016/j.anbehav.2016.11.020. S2CID 53183887.

32. ^ Graf, P. M.; Mayer, M.; Zedrosser, A.; Hackländer, K.; Rosell, F. (2016). "Territory size and age explain movement patterns in the Eurasian beaver". Mammalian Biology - Zeitschrift für Säugetierkunde. 81 (6): 587-594. doi:10.1016/j.mambio.2016.07.046.

33. ^ Rosell, Frank; Nolet, Bart A. (1997). "Factors Affecting Scent-Marking Behavior in Eurasian Beaver (Castor fiber)". Journal of Chemical Ecology. 23 (3): 673-689. doi:10.1023/B:JOEC.0000006403.74674.8a. hdl:11250/2438031. S2CID 31782872.

34. ^ Sun, Lixing; Muller-Schwarze, Dietland (1998). "Anal Gland Secretion Codes for Relatedness in the Beaver, Castor canadensis". . 104 (11): 917-927. doi:10.1111/j.1439-0310.1998.tb00041.x.

35. ^ Callahan, M. (April 2005). "Best Management Solutions for Beaver Problems" (PDF). Association of Massachusetts Wetland Scientists: 12-14. Archived (PDF) from the original on October 9, 2022.

36. ^ "Beaver Damage Management" (PDF). US Department of Agriculture. January 2011. Archived (PDF) from the original on October 9, 2022.

37. ^ Bailey, D. R.; Dittbrenner, B. J.; Yocom, K. P. (2018). "Reintegrating the North American beaver (Castor canadensis) in the urban landscape" (PDF). WIREs Water. 6 (1): e1323. doi:10.1002/wat2.1323. S2CID 85513383. Archived (PDF) from the original on October 9, 2022.

38. ^ L. Riley, Ann (2016). Restoring Neighborhood Streams - Planning, Design, and Construction. Washington, DC: Island Press. pp. 177-178. ISBN 978-1610917407.

39. ^ Madsen, Axl (January 30, 2001). John Jacob Astor: America's First Multimillionaire. Wiley. pp. 2, 4, 49, 226-231. ISBN 9780471385035.

40. Francis, Margot (2004). "The Strange Career of the Canadian Beaver: Anthropomorphic Discourses and Imperial History". Journal of Historical Sociology. 17 (2-3): 209-239. doi:10.1111/j.1467-6443.2004.00231.x.

Further reading

External links

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Beavers (genus Castor ) are large, semiaquatic rodents of the Northern Hemisphere. There are two existing species: the North American beaver ( Castor canadensis) and the Eurasian beaver ( C. fiber). Beavers are the second-largest living rodents, after capybaras, weighing up to 50 kg (110 lb).

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"Nearly a third of Flanders' 64 native butterfly species have become extinct in the past 100 years. More sensitive to environmental changes than other organisms, butterflies are considered the 'canary in the coal mine' - an early warning of habitat deterioration and its impending impact on other organisms. Mmanure for Flanders' high-production agriculture introduces some of Europe's highest levels of nitrogen into the environment."

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Published online 21 June 2001 | Nature | doi:10.1038/news010621-11

News

Northern Belgium is the European hot spot for butterfly extinction.

In a flap: agriculture and urbanisation is killing butterflies

More butterfly species are becoming extinct in northern Belgium than in any other part of Europe. Urbanization and intensive agriculture are probably to blame, new research suggests.

Nearly a third of Flanders' 64 native butterfly species have become extinct in the past 100 years; half of those remaining are endangered, report Dirk Maes of the Institute of Nature Conservation in Brussels and Hans Van Dyck of the University of Antwerp, Belgium. At this rate, the endangered butterfly species could disappear in just 65 years, the researchers predict.

More sensitive to environmental changes than other organisms, butterflies are considered the 'canary in the coal mine' - an early warning of habitat deterioration and its impending impact on other organisms. Butterflies are threatened elsewhere in the world, but censuses have generally been conducted in Western Europe, because smaller geographical areas make counting easier.

"Flanders may look green to a visitor, but most habitats are seriously affected by intensive agricultural practices," says Maes. One of the most densely populated regions in Europe, Flanders' explosion of roads and housing has eroded surrounding natural habitats and kept nature reserves among the smallest in Europe.

Furthermore, manure for Flanders' high-production agriculture introduces some of Europe's highest levels of nitrogen into the environment. The European Union recently warned Belgium that it was applying too much nitrogen to its soils.

Nitrogen causes excessive grass growth in meadows where many butterflies live. The added shade cools the ground, killing caterpillars adapted to warmer climates.

"The authors build an extremely strong case showing the effects of land-use changes on biodiversity loss," says butterfly expert Carol Boggs, director of the Center for Conservation Biology at Stanford University in California. "The impacts are becoming more pervasive across the landscape."

Nature reserves may also be at fault. Many reserves are shrinking and are managed with only plants, birds and mammals in mind. They don't account for the needs of butterflies, says Maes. For example, cattle in one reserve were grazing on plants that one species of butterfly called home, with the result that the butterfly became extinct.

Maes and Van Dyck took advantage of Europe's long history of amateur butterfly-watching. They compared nineteenth-century records with modern-day field observations. Unfortunately, the lack of high-speed transportation in the nineteenth century limited the area over which amateurs regularly observed butterflies. The researchers were therefore also limited to data from only 23% of Flanders.

Early analyses of more detailed field data collected throughout Flanders during the past decade lead Maes and Van Dyck to suspect that they have underestimated the butterfly loss. For example, they thought that the population of Maculinea alcon, the most endangered butterfly in Flanders, had declined by about 70%. They now put the figure closer to 90%.

Maes and his colleagues have drafted an action plan for M. alcon. It calls for the enlargement of the butterfly's habitats and the cutting back of plants that compete with those on which butterflies and caterpillars live.

References

Maes, D. & Van Dyck, H.Butterfly diversity loss in Flanders (north Belgium): Europe's worst case scenario?. Biological Conservation 99, 263 - 276 (2001). /pubyear>). | Article | ISI |

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Published online 21 June 2001 | Nature | doi:10.1038/news010621-11 News Northern Belgium is the European hot spot for butterfly extinction. In a flap: agriculture and urbanisation is killing butterflies More butterfly species are becoming extinct in northern Belgium than in any other part of Europe.

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"The reasons for the bat’s decline are : loss of habitat, large-scale agriculture, fewer wintering sites."

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No bat specialist goes out without a bat detector. David Gallens from Natuurpunt, our guide for tonight's bat walk, has his. The device, not much bigger than an oversized mobile phone, translates ultrasonic noise into sounds that the human ear can detect. With one click, the night silence is suddenly transformed into a symphony of hidden sounds.

The first noises come from insects, then a short series of nervous clicks reveals that dwarf bats are hunting somewhere nearby. A few moments later, the detector reveals another sound. This time it's a Daubenton's bat, explains Gallens. The fact that we can't hear the real sounds is actually a blessing because the noise of some species measures more than 100 decibels. In order not to be deafened by their own din, bats are able to close their ears in a fraction of a second.

As if there by invitation, a bat flies above the pond at the end of the walk, fluttering around above the water. Gallens draws our attention to a sound that can be heard even without the detector. Not all sounds bats make are ultrasonic: Social sounds, intended not for hunting but for communication, have a lower frequency and can be heard by humans. It's probably a cry meant to attract females; the mating season is in full swing.

The walk, on the grounds of the agricultural school in Melle, East Flanders, was part of last month's International Bat Night, an annual worldwide event that invites people to take part in night-time walks and talks to discover bats and their habitat. Events in Flanders are organised by nature conservation agency Natuurpunt, and this year, more than 6,000 people took part.

Still, things are not going well for Flanders' bats, says Wout Willems, bat specialist at Natuurpunt. "Some species like the pipistrelle, which live close to us humans, are doing fine, but just about all the other species are threatened. They are a vulnerable population. Bats have only one young each year, so their numbers recover very slowly."

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Bat population in Flanders still on the decline

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No bat specialist goes out without a bat detector. David Gallens from Natuurpunt, our guide for tonight's bat walk, has his. The device, not much bigger than an oversized mobile phone, translates ultrasonic noise into sounds that the human ear can detect. With one click, the night silence is suddenly transformed into a symphony of hidden sounds.

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"Business-as-usual" scenario: ± 20% of Flanders and Brussels will be hardened by 2050 (red on the map below).
source: https://www.kuleuven.be/hydr/cci/CCI-HYDR_urb.htm

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"Flanders is one of the most fragmented regions of Europe. Landscape fragmentation negatively
affects the ecological connectivity and biodiversity. The construction of green bridges (also
known as wildlife overpasses) is one of the responses of the Flemish government to address
this issue."

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https://klimaat.vmm.be/nl

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"The dry spring and the dry summer of 2017 caused water shortages. Due to climate change, such dry periods are likely to occur more frequently in the future, with potentially large consequences for the water system: low water levels in waterways and canals, droughts and pools, low groundwater levels, falling water quality,"

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Om de ernst van een waterschaarste- en droogtetoestand beter te kunnen inschatten, wordt gebruik gemaakt van indicatoren. Meetresultaten en voorspellingen van neerslaghoeveelheden, rivierafvoeren, grondwaterpeilen en waterkwaliteitsparameters worden daarvoor verwerkt tot 'droogte-indicatoren' en opgedeeld in vier niveaus, van een normale situatie tot een extreem droge situatie. De indicatoren worden minstens om de maand berekend.

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Number of dry days per year will increase.

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I have mainly looked at the BioAreas of Belgians and of regions where I have been on hollidays. As far as the latter is concerned, the regions of the Mediterranean are indeed richer in biodiversity. Of course the climate is an important driving factor for biodiversity. But the Mediterranean areas also have their problems when it comes to threats. In Belgium, more specific in Flanders, the fragmentation of the habitats is a major problem.

Feel free to comment !

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Theme 2: Why were wolves reintroduced in Yellowstone National Park?

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Theme 2: Why were wolves reintroduced in Yellowstone National Park?

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The wolves were brought in because the increased elk population. Source: http://www.bbc.com/future/story/20140128-how-wolves-saved-a-famous-park.

But also: in the 1960s and 1970s, national awareness of environmental issues and consequences led to the passage of many laws. By 1978, all wolf subspecies were on the federal list of endangered species for the lower 48 states except Minnesota. National Park Service policy also calls for restoration of native species where possible. Source:
https://www.nps.gov/yell/learn/nature/wolf-restoration.htm

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I've already visited the Royal Belgian Institute of Natural Sciencesin Brussels. For children famous for it's dino's.

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Situated in the central part of Belgium, 8 km south of Leuven (Flanders), in the valley of the middle course of the river Dijle. The valley contains a lot of wetland areas, which periodically flood due to the regime in the river. The entire valley of the Dijle is greatly influenced by groundwater seepage. Because the Doode Bemde nature reserve wetlands are predominantly fed by discharging groundwater they are mainly characterized by specific vegetation, which are plant species that occur exclusively in or are limited to the sphere of influence of the groundwater table.

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Learn about and visualise the protected area Doode Bemde (Certified Nature Reserve (Flemish Region)), situated in Belgium

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LTER (= Long-Term Ecosystem Research NetworkBelgium) - site

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LTER (= Long-Term Ecosystem Research NetworkBelgium) - site

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Since 1990, human interference in the river channel has stopped resulting in a spontaneous meander evolution and roughening of the river channel. This has induced frequent (e.g. yearly) inundations, thus avoiding flood damage in the city of Leuven downstream and this without creating the usual storm basins.

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Belgian Biodiversity Platform : Doode Bemde (LTER_EU_BE_29)

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The river Dyle in Leuven  - a blessing and a curse

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The river Dyle in Leuven  - a blessing and a curse

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It is the story of more than 120 years of struggling to develop and implement a strategy to keep the flooding of the River Dyle in Leuven and its surroundings under control. See chapter 4 about the "Doode Bemde".

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Issue - This publication aims to illustrate how perceptions and approaches to flood and water have changed using the River Dyle in Leuven as an example. It is the story of more than 120 years of struggling to develop and implement a strategy to keep the flooding of the River Dyle in Leuven and its surroundings under control.

The natural processes resulting in "wet" valley floors along the River Dyle upstream of Leuven have been restored. Infrastructure works are kept to a minimum and are intended to 'guide' for the river rather than to contain it.

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The river Dyle in Leuven (Belgium) - a blessing and a curse

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This publication aims to illustrate how perceptions and approaches to flood and water have changed using the River Dyle in Leuven as an example. It is the story of more than 120 years of struggling to develop and implement a strategy to keep the flooding of the River Dyle in Leuven and its surroundings under control.

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Species list of what you can see (or hear):

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Neerijse - Doode Bemde | Waarnemingen.be

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Waarnemingen.be - Alle waarnemingen uit de natuur online

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The "role" or the "job" of an organism in the ecosystem it lives in.

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Unlike other mammals, beavers can digest cellulose. Beavers eat leaves, roots and bark from aspens, willows, maples and poplar trees. They also eat aquatic plants and.... in Doode Bemde:  agricultural crop such as maize....

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Beavers (genus Castor) are large, semiaquatic rodents of the Northern Hemisphere. There are two existing species: the North American beaver ( Castor canadensis) and the Eurasian beaver ( C. fiber). Beavers are the second-largest living rodents, after capybaras, weighing up to 50 kg (110 lb). They have stout bodies with large heads, long chisel-like incisors, brown or gray fur, hand-like front feet, webbed back feet, and tails that are flat and scaly. The two species differ in skull and tail shape and fur color. Beavers can be found in a number of freshwater habitats, such as rivers, streams, lakes and ponds. They are herbivorous, consuming tree bark, aquatic plants, grasses and sedges.

Beavers build dams and lodges using tree branches, vegetation, rocks and mud; they chew down trees for building material. Dams restrict water flow, and lodges serve as shelters. Their infrastructure creates wetlands used by many other species, and because of their effect on other organisms in the ecosystem, beavers are considered a keystone species. Adult males and females live in monogamous pairs with their offspring. After their first year, the young help their parents repair dams and lodges; older siblings may also help raise newly-born offspring. Beavers hold territories and mark them using scent mounds made of mud, debris, and castoreum-a liquid substance excreted through the beaver's urethra-based castor sacs. Beavers can also recognize their kin by their anal gland secretions and are more likely to tolerate them as neighbors.

Historically, beavers have been hunted for their fur, meat, and castoreum. Castoreum has been used in medicine, perfume, and food flavoring; beaver pelts have been a major driver of the fur trade. Before protections began in the 19th and early 20th centuries, overhunting had nearly exterminated both species. Their populations have since rebounded, and they are listed as species of least concern by the IUCN Red List of mammals. In human culture, the beaver symbolizes industriousness, especially in connection with construction; it is the national animal of Canada.

There are two extant species: the North American beaver ( Castor canadensis) and the Eurasian beaver ( C. fiber). The Eurasian beaver is slightly longer and has a more lengthened skull, triangular nasal cavities (as opposed to the square ones of the North American species), a lighter fur color, and a narrower tail.

Carl Linnaeus coined the genus Castor in 1758; he also coined the specific (species) epithet fiber. German zoologist Heinrich Kuhl coined C. canadensis in 1820. However, they were not confirmed to be separate species until the 1970s, when chromosomal evidence became available. (The Eurasian has 48 chromosomes, while the North American has 40.) Prior to that, many considered them the same species. The difference in chromosome numbers prevents them from interbreeding. Twenty-five subspecies have been classified for C. canadensis, and nine have been classified for C. fiber.

Phylogeny of extant and extinct relatives of modern beavers based on genetics and morphology.

Beavers belong to the rodent suborder Castorimorpha, along with Heteromyidae ( kangaroo rats and kangaroo mice), and the gophers. Modern beavers are the only extant members of the family Castoridae. They originated in North America in the late Eocene and colonized Eurasia via the Bering Land Bridge in the early Oligocene, coinciding with the Grande Coupure, a time of significant changes in animal species around 33million years ago ( myr).

The more basal castorids had several unique features: more complex occlusion between cheek teeth, parallel rows of upper teeth, premolars that were only slightly smaller than molars, the presence of a third set of premolars (P3), a hole in the stapes of the inner ear, a smooth palatine bone (with the palatine opening closer to the rear end of the bone), and a longer snout. More derived castorids have less complex occlusion, upper tooth rows that create a V-shape towards the back, larger second premolars compared to molars, absence of a third premolar set and stapes hole, a more grooved palatine (with the opening shifted towards the front), and reduced incisive foramen. Members of the subfamily Palaeocastorinae appeared in late-Oligocene North America. This group consisted primarily of smaller animals with relatively large front legs, a flattened skull, and a reduced tail-all features of a fossorial (burrowing) lifestyle.

In the early Miocene (about 24 mya), castorids evolved a semiaquatic lifestyle. Members of the subfamily Castoroidinae are considered to be a sister group to modern beavers, and included giants like Castoroides of North America and Trogontherium of Eurasia. Castoroides is estimated to have had a length of 1.9-2.2 m (6.2-7.2 ft) and a weight of 90-125 kg (198-276 lb). Fossils of one genus in Castoroidinae, , have been found near piles of chewed wood, though Dipoides appears to have been an inferior woodcutter compared to Castor. Researchers suggest that modern beavers and Castoroidinae shared a bark-eating common ancestor. Dam and lodge-building likely developed from bark-eating, and allowed beavers to survive in the harsh winters of the subarctic. There is no conclusive evidence for this behavior occurring in non- Castor species.

The genus Castor likely originated in Eurasia. The earliest fossil remains appear to be C. neglectus, found in Germany and dated 12-10 mya. Mitochondrial DNA studies place the common ancestor of the two living species at around 8 mya. The ancestors of the North American beaver would have crossed the Bering Land Bridge around 7.5 mya. Castor may have competed with members of Castoroidinae, which led to niche differentiation. The fossil species C. praefiber was likely an ancestor of the Eurasian beaver. C. californicus from the Early Pleistocene of North America was similar to but larger than the extant North American beaver.

Characteristics

Beavers are the second-largest living rodents, after capybaras. They have a head-body length of 80-120 cm (31-47 in), with a 25-50 cm (9.8-19.7 in) tail, a shoulder height of 30-60 cm (12-24 in), and generally weigh 11-30 kg (24-66 lb), but can be as heavy as 50 kg (110 lb). Males and females are almost identical externally. Their bodies are streamlined like marine mammals and their robust build allows them to pull heavy loads. A beaver coat has 12,000-23,000 hairs/cm ² (77,000-148,000 hairs/in ²) and functions to keep the animal warm, to help it float in water, and to protect it against predators. Guard hairs are 5-6 cm (2.0-2.4 in) long and typically reddish brown, but can range from yellowish brown to nearly black. The underfur is 2-3 cm (0.79-1.18 in) long and dark gray. Beavers molt every summer.

Beavers have large skulls with powerful chewing muscles. They have four chisel-shaped incisors that continue to grow throughout their lives. The incisors are covered in a thick enamel that is colored orange or reddish-brown by iron compounds. The lower incisors have roots that are almost as long as the entire lower jaw. Beavers have one premolar and three molars on all four sides of the jaws, adding up to 20 teeth. The molars have meandering ridges for grinding woody material. The eyes, ears and nostrils are arranged so that they can remain above water while the rest of the body is submerged. The nostrils and ears have valves that close underwater, while nictitating membranes cover the eyes. To protect the larynx and trachea from water flow, the epiglottis is contained within the nasal cavity instead of the throat. In addition, the back of the tongue can rise and create a waterproof seal. A beaver's lips can close behind the incisors, preventing water from entering their mouths as they cut and bite onto things while submerged.

The beaver's front feet are dexterous, allowing them to grasp and manipulate objects and food, as well as dig. The hind feet are larger and have webbing between the toes, and the second innermost toe has a "double nail" used for grooming. Beavers can swim at 8 km/h (5.0 mph); only their webbed hind feet are used to swim, while the front feet fold under the chest. On the surface, the hind limbs thrust one after the other; while underwater, they move at the same time. Beavers are awkward on land but can move quickly when they feel threatened. They can carry objects while walking on their hind legs.

The beaver's distinctive tail has a conical, muscular, hairy base; the remaining two-thirds of the appendage is flat and scaly. The tail has multiple functions: it provides support for the animal when it is upright (such as when chewing down a tree), acts as a rudder when it is swimming, and stores fat for winter. It also has a countercurrent blood vessel system which allows the animal to lose heat in warm temperatures and retain heat in cold temperatures.

The beaver's sex organs are inside the body, and the male's penis has a cartilaginous baculum. They have only one opening, a cloaca, which is used for reproduction, scent-marking, defecation, and urination. The cloaca evolved secondarily, as most mammals have lost this feature, and may reduce the area vulnerable to infection in dirty water. The beaver's intestine is six times longer than its body, and the caecum is double the volume of its stomach. Microorganisms in the caecum allow them to process around 30 percent of the cellulose they eat. A beaver defecates in the water, leaving behind balls of sawdust. Female beavers have four mammary glands; these produce milk with 19 percent fat, a higher fat content than other rodents. Beavers have two pairs of glands: castor sacs, which are part of the urethra, and anal glands. The castor sacs secrete castoreum, a liquid substance used mainly for marking territory. Anal glands produce an oily substance which the beaver uses as a waterproof ointment for its coat. The substance plays a role in individual and family recognition. Anal secretions are darker in females than males among Eurasian beavers, while the reverse is true for the North American species.

Compared to many other rodents, a beaver's brain has a hypothalamus that is much smaller than the cerebrum; this indicates a relatively advanced brain with higher intelligence. The cerebellum is large, allowing the animal to move within a three-dimensional space (such as underwater) similar to tree-climbing squirrels. The neocortex is devoted mainly to touch and hearing. Touch is more advanced in the lips and hands than the whiskers and tail. Vision in the beaver is relatively poor; the beaver eye cannot see as well underwater as an otter. Beavers have a good sense of smell, which they use for detecting land predators and for inspecting scent marks, food, and other individuals.

Beavers can hold their breath for as long as 15 minutes but typically remain underwater for no more than five or six minutes. Dives typically last less than 30 seconds and are usually no more than 1 m (3 ft 3 in) deep. When diving, their heart rate decreases to 60 beats per minute, half its normal pace, and blood flow is directed more towards the brain. A beaver's body also has a high tolerance for carbon dioxide. When surfacing, the animal can replace 75 percent of the air in its lungs in one breath, compared to 15 percent for a human.

Distribution and status

North American beaver in Yellowstone National Park

The IUCN Red List of mammals lists both beaver species as least concern. The North American beaver is widespread throughout most of the United States and Canada and can be found in northern Mexico. The species was introduced to Finland in 1937 (and then spread to northwestern Russia) and to Tierra del Fuego, Patagonia, in 1946. As of 2019, the introduced population of North American beavers in Finland has been moving closer to the habitat of the Eurasian beaver. Historically, the North American beaver was trapped and nearly extirpated because its fur was highly sought after. Protections have allowed the beaver population on the continent to rebound to an estimated 6-12million by the late 20th century; still far lower than the originally estimated 60-400million North American beavers before the fur trade. The introduced population in Tierra del Fuego is estimated at 35,000-50,000 individuals as of 2016.

The Eurasian beaver's range historically included much of Eurasia, but was decimated by hunting by the early 20th century. In Europe, beavers were reduced to fragmented populations, with combined population numbers being estimated at 1,200 individuals for the Rhône of France, the Elbe in Germany, southern Norway, the Neman river and Dnieper Basin in Belarus, and the Voronezh river in Russia. The beaver has since recolonized parts of its former range, aided by conservation policies and reintroductions. Beaver populations now range across western, central, and eastern Europe, and western Russia and the Scandinavian Peninsula. Beginning in 2009, beavers have been successfully reintroduced to parts of Great Britain. In 2020, the total Eurasian beaver population in Europe was estimated at over one million. Small native populations are also present in Mongolia and northwestern China; their numbers were estimated at 150 and 700, respectively, as of 2016. Under New Zealand's Hazardous Substances and New Organisms Act 1996, beavers are classed as a "prohibited new organism" preventing them from being introduced into the country.

Eurasian beavers swimming and foraging

Beavers live in freshwater ecosystems such as rivers, streams, lakes and ponds. Water is the most important part of beaver habitat; they swim and dive in it, and it provides them a refuge from land predators, restricts access to their homes and allows them to move building objects more easily. Beavers prefer slower moving streams, typically with a gradient (steepness) of one percent, though they have been recorded using streams with gradients as high as 15 percent. Beavers are found in wider streams more often than in narrower ones. They also prefer areas with no regular flooding and may abandon a location for years after a significant flood.

Beavers typically select flat landscapes with diverse vegetation close to the water. North American beavers prefer trees being 60 m (200 ft) or less from the water, but will roam several hundred meters to find more. Beavers have also been recorded in mountainous areas. Dispersing beavers will use certain habitats temporarily before finding their ideal home. These include small streams, temporary swamps, ditches, and backyards. These sites lack important resources, so the animals do not stay there permanently. Beavers have increasingly settled at or near human-made environments, including agricultural areas, suburbs, golf courses, and shopping malls.

Beavers have an herbivorous and a generalist diet. During the spring and summer, they mainly feed on herbaceous plant material such as leaves, roots, herbs, ferns, grasses, sedges, water lilies, water shields, rushes, and cattails. During the fall and winter, they eat more bark and cambium of woody plants; tree and shrub species consumed include aspen, birch, oak, dogwood, willow and alder. There is some disagreement about why beavers select specific woody plants; some research has shown that beavers more frequently select species which are more easily digested, while others suggest beavers principally forage based on stem size. Beavers may cache their food for the winter, piling wood in the deepest part of their pond where it cannot be reached by other browsers. This cache is known as a "raft"; when the top becomes frozen, it creates a "cap". The beaver accesses the raft by swimming under the ice. Many populations of Eurasian beaver do not make rafts, but forage on land during winter.

Beavers usually live up to 10 years. Felids, canids, and bears may prey upon them. Beavers are protected from predators when in their lodges, and prefer to stay near water. Parasites of the beaver include the bacteria Francisella tularensis, which causes tularemia; the protozoan Giardia duodenalis, which causes giardiasis (beaver fever); and the beaver beetle and mites of the genus Schizocarpus. They have also been recorded to be infected with the rabies virus.

Infrastructure

Beavers need trees and shrubs to use as building material for dams, which restrict flowing water to create a pond for them to live in, and for lodges, which act as shelters and refuges from predators and the elements. Without such material, beavers dig burrows into a bank to live. Dam construction begins in late summer or early fall, and they repair them whenever needed. Beavers can cut down trees up to 15 cm (5.9 in) wide in less than 50 minutes. Thicker trees, at 25 cm (9.8 in) wide or more, may not fall for hours. When chewing down a tree, beavers switch between biting with the left and right side of the mouth. Tree branches are then cut and carried to their destination with the powerful jaw and neck muscles. Other building materials, like mud and rocks, are held by the forelimbs and tucked between the chin and chest.

Beaver start building dams when they hear running water, and the sound of a leak in a dam triggers them to repair it. To build a dam, beavers stack up relatively long and thick logs between banks and in opposite directions. Heavy rocks keep them stable, and grass is packed between them. Beavers continue to pile on more material until the dam slopes in a direction facing upstream. Dams can range in height from 20 cm (7.9 in) to 3 m (9.8 ft) and can stretch from 0.3 m (1 ft 0 in) to several hundred meters long. Beaver dams are more effective in trapping and slowly leaking water than man-made concrete dams. Lake-dwelling beavers do not need to build dams.

Beavers make two types of lodges: bank lodges and open-water lodges. Bank lodges are burrows dug along the shore and covered in sticks. The more complex freestanding, open-water lodges are built over a platform of piled-up sticks. The lodge is mostly sealed with mud, except for a hole at the top which acts as an air vent. Both types are accessed by underwater entrances. The above-water space inside the lodge is known as the "living chamber", and a "dining area" may exist close to the water entrance. Families routinely clean out old plant material and bring in new material.

North American beavers build more open-water lodges than Eurasian beavers. Beaver lodges built by new settlers are typically small and sloppy. More experienced families can build structures with a height of 2 m (6 ft 7 in) and an above-water diameter of 6 m (20 ft). A lodge sturdy enough to withstand the coming winter can be finished in just two nights. Both lodge types can be present at a beaver site. During the summer, beavers tend to use bank lodges to keep cool. They use open-water lodges during the winter. The air vent provides ventilation, and newly-added carbon dioxide can be cleared in an hour. The lodge remains consistent in oxygen and carbon dioxide levels from season to season.

Beavers in some areas will dig canals connected to their ponds. The canals fill with groundwater and give beavers access and easier transport of resources, as well as allow them to escape predators. These canals can stretch up to 1 m (3 ft 3 in) wide, 0.5 m (1 ft 8 in) deep, and over 0.5 km (0.31 mi) long. It has been hypothesized that beavers' canals are not only transportation routes but an extension of their " central place" around the lodge and/or food cache. As they drag wood across the land, beavers leave behind trails or "slides", which they reuse when moving new material.

Environmental effects

The beaver works as an ecosystem engineer and keystone species, as its activities can have a great impact on the landscape and biodiversity of an area. Aside from humans, few other extant animals appear to do more to shape their environment. When building dams, beavers alter the paths of streams and rivers, allowing for the creation of extensive wetland habitats. In one study, beavers were associated with large increases in open-water areas. When beavers returned to an area, 160% more open water was available during droughts than in previous years, when they were absent. Beaver dams also lead to higher water tables in mineral soil environments and in wetlands such as peatlands. In peatlands particularly, their dams stabilize the constantly changing water levels, leading to greater carbon storage.

Beaver ponds, and the wetlands that succeed them, remove sediments and pollutants from waterways, and can stop the loss of important soils. These ponds can increase the productivity of freshwater ecosystems by accumulating nitrogen in sediments. Beaver activity can affect the temperature of the water; in northern latitudes, ice thaws earlier in the warmer beaver-dammed waters. Beavers may contribute to climate change. In Arctic areas, the floods they create can cause permafrost to thaw, releasing methane into the atmosphere.

As wetlands are formed and riparian habitats are enlarged, aquatic plants colonize the newly-available watery habitat. One study in the Adirondacks found that beaver engineering lead to an increase of more than 33 percent in herbaceous plant diversity along the water's edge. Another study in semiarid eastern Oregon found that the width of riparian vegetation on stream banks increased several-fold as beaver dams watered previously dry terraces adjacent to the stream. Riparian ecosystems in arid areas appear to sustain more plant life when beaver dams are present. Beaver ponds act as a refuge for riverbank plants during wildfires, and provide them with enough moisture to resist such fires. Introduced beavers at Tierra del Fuego have been responsible for destroying the indigenous forest. Unlike trees in North America, many trees in South America cannot grow back after being cut down.

Salmon (Oncorhynchus nerka) jumping a beaver dam

Beaver activity impacts communities of aquatic invertebrates. Damming typically leads to an increase of slow or motionless water species, like dragonflies, oligochaetes, snails, and mussels. This is to the detriment of rapid water species like black flies, stoneflies, and net-spinning caddisflies. Beaver floodings create more dead trees, providing more habitat for terrestrial invertebrates like Drosophila flies and bark beetles, which live and breed in dead wood. The presence of beavers can increase wild salmon and trout populations, and the average size of these fishes. These species use beaver habitats for spawning, overwintering, feeding, and as havens from changes in water flow. The positive effects of beaver dams on fish appear to outweigh the negative effects, such as blocking of migration. Beaver ponds have been shown to be beneficial to frog populations by protecting areas for larvae to mature in warm water. The stable waters of beaver ponds also provide ideal habitat for freshwater turtles.

Beavers help waterfowl by creating increased areas of water. The widening of the riparian zone associated with beaver dams has been shown to increase the abundance and diversity of birds favoring the water's edge, an impact that may be especially important in semi-arid climates. Fish-eating birds use beaver ponds for foraging, and in some areas, certain species appear more frequently at sites where beavers were active than at sites with no beaver activity. In a study of Wyoming streams and rivers, watercourses with beavers had 75 times as many ducks as those without. As trees are drowned by rising beaver impoundments, they become an ideal habitat for woodpeckers, which carve cavities that may be later used by other bird species. Beaver-caused ice thawing in northern latitudes allows Canada geese to nest earlier.

Other semi-aquatic mammals, such as water voles, muskrats, minks, and otters, will shelter in beaver lodges. Beaver modifications to streams in Poland create habitats favorable to bat species that forage at the water surface and "prefer moderate vegetation clutter". Large herbivores, such as some deer species, benefit from beaver activity as they can access vegetation from fallen trees and ponds.

Beavers are mainly nocturnal and crepuscular, and spend the daytime in their shelters. In northern latitudes, beaver activity is decoupled from the 24-hour cycle during the winter, and may last as long as 29 hours. They do not hibernate during winter, and spend much of their time in their lodges.

Family life

The core of beaver social organization is the family, which is composed of an adult male and an adult female in a monogamous pair and their offspring. Beaver families can have as many as ten members; groups about this size require multiple lodges. Mutual grooming and play fighting maintain bonds between family members, and aggression between them is uncommon.

Adult beavers mate with their partners, though partner replacement appears to be common. A beaver that loses its partner will wait for another one to come by. Estrus cycles begin in late December and peak in mid-January. Females may have two to four estrus cycles per season, each lasting 12-24 hours. The pair typically mate in the water and to a lesser extent in the lodge, for half a minute to three minutes.

Up to four young, or kits, are born in spring and summer, after a three or four-month gestation. Newborn beavers are precocial with a full fur coat, and can open their eyes within days of birth. Their mother is the primary caretaker, while their father maintains the territory. Older siblings from a previous litter also play a role.

After they are born, the kits spend their first one to two months in the lodge. Kits suckle for as long as three months, but can eat solid food within their second week and rely on their parents and older siblings to bring it to them. Eventually, beaver kits explore outside the lodge and forage on their own, but may follow an older relative and hold onto their backs. After their first year, young beavers help their families with construction. Beavers sexually mature around 1.5-3 years. They become independent at two years old, but remain with their parents for an extra year or more during times of food shortage, high population density, or drought.

Territories and spacing

Beavers typically disperse from their parental colonies during the spring or when the winter snow melts. They often travel less than 5 km (3.1 mi), but long-distance dispersals are not uncommon when previous colonizers have already exploited local resources. Beavers are able to travel greater distances when free-flowing water is available. Individuals may meet their mates during the dispersal stage, and the pair travel together. It may take them weeks or months to reach their final destination; longer distances may require several years. Beavers establish and defend territories along the banks of their ponds, which may be 1-7 km (0.62-4.35 mi) in length.

Beavers mark their territories by constructing scent mounds made of mud and vegetation, scented with castoreum. Those with many territorial neighbors create more scent mounds. Scent marking increases in spring, during the dispersal of yearlings, to deter interlopers. Beavers are generally intolerant of intruders and fights may result in deep bites to the sides, rump, and tail. They exhibit a behavior known as the " dear enemy effect"; a territory-holder will investigate and become familiar with the scents of its neighbors and react more aggressively to the scents of strangers passing by. Beavers are also more tolerant of individuals that are their kin. They recognize them by using their keen sense of smell to detect differences in the composition of anal gland secretions. Anal gland secretion profiles are more similar among relatives than unrelated individuals.

Communication

Beavers within a family greet each other with whines. Kits will attract the attention of adults with mews, squeaks, and cries. Defensive beavers produce a hissing growl and gnash their teeth. Tail slaps, which involve an animal hitting the water surface with its tail, serve as alarm signals warning other beavers of a potential threat. An adult's tail slap is more successful in alerting others, who will escape into the lodge or deeper water. Juveniles have not yet learned the proper use of a tail slap, and hence are normally ignored. Eurasian beavers have been recorded using a territorial "stick display", which involves individuals holding up a stick and bouncing in shallow water.

Interactions with humans

Grey Owl feeding his beaver

Beavers sometimes come into conflict with humans over land use; individual beavers may be labeled as "nuisance beavers". Beavers can damage crops, timber stocks, roads, ditches, gardens, and pastures via gnawing, eating, digging, and flooding. They occasionally attack humans and domestic pets, particularly when infected with rabies, in defense of their territory, or when they feel threatened. Some of these attacks have been fatal, including at least one human death. Beavers can spread giardiasis ('beaver fever') by infecting surface waters, though outbreaks are more commonly caused by human activity.

Flow devices, like beaver pipes, are used to manage beaver flooding, while fencing and hardware cloth protect trees and shrubs from beaver damage. If necessary, hand tools, heavy equipment, or explosives are used to remove dams. Hunting, trapping, and relocation may be permitted as forms of population control and for removal of individuals. The governments of Argentina and Chile have authorized the trapping of invasive beavers in hopes of eliminating them. The ecological importance of beavers has led to cities like Seattle designing their parks and green spaces to accommodate the animals. The Martinez beavers became famous in the mid-2000s for their role in improving the ecosystem of Alhambra Creek in Martinez, California.

Zoos have displayed beavers since at least the 19th century, though not commonly. In captivity, beavers have been used for entertainment, fur harvesting, and for reintroduction into the wild. Captive beavers require access to water, substrate for digging, and artificial shelters. Archibald Stansfeld "Grey Owl" Belaney pioneered beaver conservation in the early 20th century. Belaney wrote several books, and was first to professionally film beavers in their environment. In 1931, he moved to a log cabin in Prince Albert National Park, where he was the "caretaker of park animals" and raised a beaver pair and their four offspring.

Commercial use

Beavers have been hunted, trapped, and exploited for their fur, meat, and castoreum. Since the animals typically stayed in one place, trappers could easily find them and could kill entire families in a lodge. Many pre-modern people mistakenly thought that castoreum was produced by the testicles or that the castor sacs of the beaver were its testicles, and females were hermaphrodites. Aesop's Fables describes beavers chewing off their testicles to preserve themselves from hunters, which is impossible because a beaver's testicles are internal. This myth persisted for centuries, and was corrected by French physician Guillaume Rondelet in the 1500s. Beavers have historically been hunted and captured using deadfalls, snares, nets, bows and arrows, spears, clubs, firearms, and leg-hold traps. Castoreum was used to lure the animals.

Castoreum was used for a variety of medical purposes; Pliny the Elder promoted it as a treatment for stomach problems, flatulence, seizures, sciatica, vertigo, and epilepsy. He stated it could stop hiccups when mixed with vinegar, toothaches if mixed with oil (by administering into the ear opening on the same side as the tooth), and could be used as an antivenom. The substance has traditionally been prescribed to treat hysteria in women, which was believed to have been caused by a "toxic" womb. Castoreum's properties have been credited to the accumulation of salicylic acid from willow and aspen trees in the beaver's diet, and has a physiological effect comparable to aspirin. Today, the medical use of castoreum has declined and is limited mainly to homeopathy. The substance is also used as an ingredient in perfumes and tinctures, and as a flavouring in food and drinks.

Various Native American groups have historically hunted beavers for food. Beaver meat was advantageous, being more calorie-rich and fattened than other red meats, and the animals remained plump in winter, when they were most hunted. The bones were used to make tools. In medieval Europe, the Catholic Church considered the beaver to be part mammal and part fish, and allowed followers to eat the scaly, fishlike tail on meatless Fridays during Lent. Beaver tails were thus highly-prized in Europe; they were described by French naturalist Pierre Belon as tasting like a "nicely dressed eel".

Beaver pelts were used to make hats; felters would remove the guard hairs. The number of pelts needed depended on the type of hat, with Cavalier and Puritan hats requiring more fur than top hats. In the late 16th century, Europeans began to deal in North American furs due to the lack of taxes or tariffs on the continent and the decline of fur-bearers at home. Beaver pelts caused or contributed to the Beaver Wars, King William's War, and the French and Indian War; the trade made John Jacob Astor and the owners of the North West Company very wealthy. For Europeans in North America, the fur trade was a driver of the exploration and westward exploration on the continent and contact with native peoples, who traded with them. The fur trade peaked between 1860 and 1870, when over 150,000 beaver pelts were purchased annually by the Hudson's Bay Company and fur companies in the United States. The contemporary global fur trade is not as profitable due to conservation, anti-fur and animal rights campaigns.

Beaver sculpture over entrance to the Canadian Parliament Building

The beaver has been used to represent productivity, trade, tradition, masculinity, and respectability. References to the beaver's skills are reflected in everyday language. The English verb "to beaver" means working with great effort and being "as busy as a beaver"; a "beaver intellect" refers to a way of thinking that is slow and honest. The word "beaver" can also be used as a sexual term for the human vulva.

Native American myths emphasize the beaver's skill and industriousness. In the mythology of the Haida, beavers are descended from the Beaver-Woman, who built a dam on a stream next to their cabin while her husband was out hunting and gave birth to the first beavers. In a Cree story, the Great Beaver and its dam caused a world flood. Other tales involve beavers using their tree chewing skills against an enemy. Beavers have been featured as companions in some stories, including a Lakota tale where a young woman flees from her evil husband with the aid of her pet beaver.

Europeans have traditionally thought of beavers as fantastical animals due to their amphibious nature. They depicted them with exaggerated tusk-like teeth, dog- or pig-like bodies, fish tails, and visible testicles. French cartographer Nicolas de Fer illustrated beavers building a dam at Niagara Falls, fantastically depicting them like human builders. Beavers have also appeared in literature such as Dante Alighieri's Divine Comedy and the writings of Athanasius Kircher, who wrote that on Noah's Ark the beavers were housed near a water-filled tub that was also used by mermaids and otters.

The beaver has long been associated with Canada, appearing on the first pictorial postage stamp issued in the Canadian colonies in 1851 as the so-called " Three-Penny Beaver". It was declared the national animal in 1975. The five-cent coin, the coat of arms of the Hudson's Bay Company, and the logos for Parks Canada and Roots Canada use its image. Frank and Gordon are two fictional beavers that appeared in Bell Canada's advertisements between 2005 and 2008. However, the beaver's status as a rodent has made it controversial, and it was not chosen to be on the Arms of Canada in 1921. The beaver has commonly been used to represent Canada in political cartoons, typically to signify it as a friendly but relatively weak nation. In the United States, the beaver is the state animal of New York and Oregon. It is also featured on the coat of arms of the London School of Economics.

References

1. ^ International Commission on Zoological Nomenclature (1922). "Opinion 75. Twenty-Seven Generic Names of Protozoa, Vermes, Pisces, Reptilia and Mammalia Included in the Official List of Zoological Names". Smithsonian Miscellaneous Collections. 73 (1): 35-37.

2. ^ Busher, P.; Hartman, G. (2001). "Beavers". In MacDonald, D. W. (ed.). The Encyclopedia of Mammals (2nd ed.). Oxford University Press. pp. 590-593. ISBN 978-0760719695.

3. ^ Fabre, Pierre-Henri; Hautier, Lionel; Dimitrov, Dimitar; Douzery, Emmanuel J. P. (2012). "A glimpse on the pattern of rodent diversification: a phylogenetic approach". BMC Evolutionary Biology. 12 (88): 88. doi:10.1186/1471-2148-12-88. PMC . PMID 22697210.

4. ^ Doronina, Liliya; Matzke, Andreas; Churakov, Gennady; Stoll, Monika; Huge, Andreas; Schmitz, Jürgen (2017). "The beaver's phylogenetic lineage illuminated by retroposon reads". Scientific Reports. 7 (1): 43562. Bibcode:2017NatSR...743562D. doi:10.1038/srep43562. PMC . PMID 28256552.

5. ^ Swinehart, A. L.; Richards, R. L. (2001). "Paleoecology of Northeast Indiana Wetland Harboring Remains of the Pleistocene Giant Beaver (Castoroides Ohioensis)". Proceedings of the Indiana Academy of Science. 110: 151.

6. ^ Samuels, J. X.; Zancanella, J. (2011). "An early Hemphillian occurrence of Castor (Castoridae) from the Rattlesnake Formation of Oregon". Journal of Paleontology. 85 (5): 930-935. doi:10.1666/11-016.1. S2CID 128866799.

7. ^ Barisone, G.; Argenti, P.; Kotsakis, T. (2006). "Plio-Pleistocene evolution of the genus Castor (Rodentia, Mammalia) in Europe: C. fiber plicidens of Pietrafitta (Perugia, Central Italy)". . 39 (6): 757-770. Bibcode:2006Geobi..39..757B. doi:10.1016/j.geobios.2005.10.004.

8. ^ Baker, B. W.; Hill, E. P. (2003). "Beaver Castor canadensis". In Feldhamer, G. A.; Thompson, B. C.; Chapman, J. A. (eds.). Wild Mammals of North America: Biology, Management, and Conservation (2 ed.). Johns Hopkins University Press. pp. 289-297. ISBN 978-0801874161. OCLC 51969059.

9. ^ Campbell-Palmer, Róisín; Gow, Derek; Needham, Robert; Jones, Simon; Rosell, Frank (2015). The Eurasian Beaver. Pelagic Publishing Ltd. pp. 7-12. ISBN 978-1784270407.

10. ^ Graf, P. M.; Wilson, R. P.; Sanchez, L. C.; Hacklӓnder, K.; Rosell, F. (2017). "Diving behavior in a free‐living, semi‐aquatic herbivore, the Eurasian beaver Castor fiber". Ecology and Evolution. 8 (2): 997-1008. doi:10.1002/ece3.3726. PMC . PMID 29375773.

11. ^ Naiman, Robert J.; Johnston, Carol A.; Kelley, James C. (December 1988). "Alteration of North American Streams by Beaver" (PDF). BioScience. 38 (11): 753-762. doi:10.2307/1310784. JSTOR 1310784. Archived from the original (PDF) on March 4, 2012.

12. ^ "Beaver reintroduction in the UK". Royal Society for the Protection of Birds. Archived from the original on November 6, 2020.

13. ^ "Hazardous Substances and New Organisms Act 2003 - Schedule 2 Prohibited new organisms". New Zealand Government. Archived from the original on November 6, 2020.

14. ^ Mahoney, Michael J.; Stella, John C. (2020). "Stem size selectivity is stronger than species preferences for beaver, a central place forager". Forest Ecology and Management. 475: 118331. doi:10.1016/j.foreco.2020.118331. S2CID 224922775.

15. ^ Grudzinski, Bartosz P.; Cummins, Hays; Vang, Teng Keng (2019). "Beaver canals and their environmental effects". Progress in Physical Geography: Earth and Environment. 44 (2): 189-211. doi:10.1177/0309133319873116. S2CID 204257682.

16. ^ Rosell F; Bozser O; Collen P; Parker H (2005). "Ecological impact of beavers Castor fiber and Castor canadensis and their ability to modify ecosystems". Mammal Review. 35 (3-4): 248-276. doi:10.1111/j.1365-2907.2005.00067.x. hdl:11250/2438080.

17. ^ Burchsted, D.; Daniels, M.; Thorson, R.; Vokoun, J. (2010). "The river discontinuum: applying beaver modifications to baseline conditions for restoration of forested headwaters". BioScience. 60 (11): 908-922. doi:10.1525/bio.2010.60.11.7. S2CID 10070184.

18. ^ Hood, Glynnis A.; Bayley, Suzanne E. (2008). "Beaver (Castor canadensis) mitigate the effects of climate on the area of open water in boreal wetlands in western Canada". Biological Conservation. 141 (2): 556-567. doi:10.1016/j.biocon.2007.12.003. S2CID 84584842.

19. ^ Puttock, A.; Graham, H. A.; Carless, D.; Brazier, R. E. (2018). "Sediment and Nutrient Storage in a Beaver Engineered Wetland". Earth Surface Processes and Landforms. 43 (11): 2358-2370. Bibcode:2018ESPL...43.2358P. doi:10.1002/esp.4398. PMC . PMID 30333676.

20. Bromley, Chantal K.; Hood, Glynnis A. (2013). "Beavers (Castor canadensis) facilitate early access by Canada geese (Branta canadensis) to nesting habitat and areas of open water in Canada's boreal wetlands". Mammalian Biology. 78 (1): 73-77. doi:10.1016/j.mambio.2012.02.009.

21. ^ Jones, B. M.; Tape, K. D.; Clark, J. A.; Nitze, I.; Grosse, G.; Disbrow, J. (2020). "Increase in beaver dams controls surface water and thermokarst dynamics in an Arctic tundra region, Baldwin Peninsula, northwestern Alaska". Environmental Research Letters. 15 (7): 075005. Bibcode:2020ERL....15g5005J. doi:10.1088/1748-9326/ab80f1.

22. ^ Hunt, Kate (June 30, 2020). "Beavers are gnawing away at the Arctic permafrost, and that's bad for the planet". CNN.

23. ^ Wright, J. P.; Jones, C. G.; Flecker, A. S. (2002). "An ecosystem engineer, the beaver, increases species richness at the landscape scale" (PDF). . 132 (1): 96-101. Bibcode:2002Oecol.132...96W. doi:10.1007/s00442-002-0929-1. PMID 28547281. S2CID 5940275. Archived (PDF) from the original on October 9, 2022.

24. ^ Fairfax, E.; Small, E. E. (2018). "Using remote sensing to assess the impact of beaver damming on riparian evapotranspiration in an arid landscape". Ecohydrology. 11 (7): e1993. doi:10.1002/eco.1993. S2CID 134994160.

25. ^ Fairfax, E; Whittle, A. (2020). "Smokey the Beaver: beaver‐dammed riparian corridors stay green during wildfire throughout the western United States". Ecological Applications. 30 (8): e02225. doi:10.1002/eap.2225. PMID 32881199.

26. ^ Saarenmaa, H. (1978). "The occurrence of bark beetles (Col. Scolytidae) in a dead spruce stand flooded by beavers (Castor canadensis Kuhl)". Silva Fennica: 201-216. doi:10.14214/sf.a14857.

27. ^ Kemp, P. S.; Worthington, T. A.; Langford, T. E. L.; Tree, A. R. J.; Gaywood, M. J. (2012). "Qualitative and quantitative effects of reintroduced beavers on stream fish". Fish and Fisheries. 13 (2): 158-181. doi:10.1111/j.1467-2979.2011.00421.x.

28. ^ Cooke, Hilary A.; Zack, Steve (2008). "Influence of Beaver Dam Density on Riparian Areas and Riparian Birds in Shrubsteepe of Wyoming". Western North American Naturalist. 68 (3): 365-373. doi:10.3398/1527-0904(2008)68[365:IOBDDO]2.0.CO;2. S2CID 62833818.

29. Grover, A. M.; Baldassarre, G. A. (1995). "Bird species richness within beaver ponds in south-central New York". Wetlands. 15 (2): 108-118. doi:10.1007/BF03160664. S2CID 13053029.

30. ^ Nummbi, P.; Holopainen, S. (2014). "Whole-community facilitation by beaver: ecosystem engineer increases waterbird diversity". Aquatic Conservation: Marine and Freshwater Ecosystems. 24 (5): 623-633. doi:10.1002/aqc.2437.

31. ^ Mayer, M; Zedrosser, A; Rosell, F (2017). "When to leave: the timing of natal dispersal in a large, monogamous rodent, the Eurasian beaver". Animal Behaviour. 123: 375-382. doi:10.1016/j.anbehav.2016.11.020. S2CID 53183887.

32. ^ Graf, P. M.; Mayer, M.; Zedrosser, A.; Hackländer, K.; Rosell, F. (2016). "Territory size and age explain movement patterns in the Eurasian beaver". Mammalian Biology - Zeitschrift für Säugetierkunde. 81 (6): 587-594. doi:10.1016/j.mambio.2016.07.046.

33. ^ Rosell, Frank; Nolet, Bart A. (1997). "Factors Affecting Scent-Marking Behavior in Eurasian Beaver (Castor fiber)". Journal of Chemical Ecology. 23 (3): 673-689. doi:10.1023/B:JOEC.0000006403.74674.8a. hdl:11250/2438031. S2CID 31782872.

34. ^ Sun, Lixing; Muller-Schwarze, Dietland (1998). "Anal Gland Secretion Codes for Relatedness in the Beaver, Castor canadensis". . 104 (11): 917-927. doi:10.1111/j.1439-0310.1998.tb00041.x.

35. ^ Callahan, M. (April 2005). "Best Management Solutions for Beaver Problems" (PDF). Association of Massachusetts Wetland Scientists: 12-14. Archived (PDF) from the original on October 9, 2022.

36. ^ "Beaver Damage Management" (PDF). US Department of Agriculture. January 2011. Archived (PDF) from the original on October 9, 2022.

37. ^ Bailey, D. R.; Dittbrenner, B. J.; Yocom, K. P. (2018). "Reintegrating the North American beaver (Castor canadensis) in the urban landscape" (PDF). WIREs Water. 6 (1): e1323. doi:10.1002/wat2.1323. S2CID 85513383. Archived (PDF) from the original on October 9, 2022.

38. ^ L. Riley, Ann (2016). Restoring Neighborhood Streams - Planning, Design, and Construction. Washington, DC: Island Press. pp. 177-178. ISBN 978-1610917407.

39. ^ Madsen, Axl (January 30, 2001). John Jacob Astor: America's First Multimillionaire. Wiley. pp. 2, 4, 49, 226-231. ISBN 9780471385035.

40. Francis, Margot (2004). "The Strange Career of the Canadian Beaver: Anthropomorphic Discourses and Imperial History". Journal of Historical Sociology. 17 (2-3): 209-239. doi:10.1111/j.1467-6443.2004.00231.x.

Further reading

External links

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Beavers (genus Castor ) are large, semiaquatic rodents of the Northern Hemisphere. There are two existing species: the North American beaver ( Castor canadensis) and the Eurasian beaver ( C. fiber). Beavers are the second-largest living rodents, after capybaras, weighing up to 50 kg (110 lb).

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Beavers, are considered “ecosystem engineers” or “niche constructors”, as they create or modify habitat structure, which has a cumulative effect on ecosystem functions, habitats, resources, and

species. They are among the few species that can significantly change the hydrological characteristics and biotic properties of the landscape. In so doing, beavers increase habitat and

species heterogeneity, increasing biodiversity, at the landscape level.

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Beavers were once native to Flanders but the species have disappeared from Flanders for more than 150 years. The last wild beaver was shot in 1848 in the province. In April 2003, the species have  been reintroduced  in the  valley of the Dijle. These exposures were illegal and very controversial, but the animals now feel apparently very good in the still quite natural Dijle valley. There were already castles and other traces.

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Een studie van de Universiteit Antwerpen toont dat er in Vlaanderen voldoende leefgebied is voor meer dan 900 beverfamilies, ruim 7 keer meer dan er vandaag leven. Die vestiging zal in de praktijk niet altijd zonder uitdagingen verlopen, want de bever is een echte landschapsarchitect. Toch zijn er in veel gevallen oplossingen die een conflictloos samenleven tussen mens en bever mogelijk maken.
Bevers zijn een belangrijke schakel binnen de Vlaamse natuur, en hun herstel is een goed voorbeeld van de terugkeer van "grote Europese natuur", zelfs in het dichtbevolkte Vlaanderen. Deze strikte vegetariërs knagen bomen om, graven kanaaltjes, bouwen burchten en soms ook een dam. Hierdoor krijgen een aantal natuurlijke processen, zoals vernatting en verjonging van de vegetatie bij vestiging, en vervolgens het weer langzaam verbossen bij het verlaten van het gebied, kans om plaats te vinden. Door deze aanpassingen creëren ze afwisseling in het landschap, zowel in de waterloop als erbuiten, waar bijvoorbeeld insecten, padden en salamanders, watervogels en vleermuizen dankbaar gebruik van kunnen maken. Voor de mens is het samenleven met bevers soms opnieuw wat wennen.

Vorige week nog haalden de wilde bevers die in het Waalse pretpark Walibi leven het nieuws. Ze bedreigden een attractie door bomen in de buurt om te knagen. Eerst werd bericht over het plan om de bevers te doden, ondanks hun beschermde en bedreigde status. Hierop bood een dierenpark aan om ze op te vangen. Tenslotte werd in samenwerking met Natagora (de Waalse zusterorganisatie van Natuurpunt) een voorstel gemaakt waarbij de bevers zouden mogen blijven, en ervoor gezorgd wordt (via afrastering) dat de bomen die potentieel gevaarlijk zijn voor de attractie niet omgeknaagd kunnen worden.

Al is de uitkomst van bovenstaand voorbeeld positief, toch kunnen we beter preventief te werk gaan: door maatregelen te nemen die conflicten voorkomen. Als er nadien toch nog problemen optreden, kunnen we specifieke situaties oplossen, rekening houdend met mens en dier. Pas in allerlaatste instantie kan gegrepen worden naar verplaatsingen.
Bevers in Vlaanderen
Nadat de laatste bever in 1848 uitgeroeid werd in Vlaanderen was de soort gedurende anderhalve eeuw weg uit Vlaanderen. Bevers zijn beschermd door Europa. Sinds het begin van de 21e eeuw verspreiden deze ecosysteemingenieurs zich weer in Vlaanderen, en momenteel wordt het aantal territoria geschat op ongeveer 120. Het Vlaamse soortbeschermingsprogramma voor de bever mikt op een minimum van 167 families. Uit de recente studie van de Universiteit Antwerpen blijkt dat er nog veel meer potentieel geschikt leefgebied aanwezig is.
Uitdagingen en oplossingen
Waar bevers terugkeren, treden soms conflicten op met de mens. Maar voor elk van die mogelijke conflicten bestaan er (of wordt er gewerkt aan) oplossingen die een duurzaam samenleven mogelijk maken.

Bevers zijn planteneters, die ook schors van bomen eten. Om meer schors ter beschikking te hebben, knagen ze bomen om. Een slimme manier om aan meer eten te komen. Indien er daardoor veiligheidsproblemen optreden, of als het gaat om landschappelijk of economisch belangrijke bomen, dan kunnen de bomen beschermd worden door een kraag van stevig metaalgaas.

Bevers graven holen in oevers. Afhankelijk van de stevigheid van de oever kan dat een probleem vormen. Op zeer gevoelige plaatsen kan verhoogde monitoring problemen snel opsporen. In Nederland wordt op kritische locaties draad in dijken ingewerkt om de structurele veiligheid van deze waterkeringen te garanderen.

Het bouwen van dammen zorgt voor de meeste bezorgdheden binnen Vlaanderen. Dammen worden echter alleen gebouwd op ondiepe, relatief smalle waterlopen. Er zijn ook veel bevers die zich vestigen op stilstaande wateren of bredere rivieren waar ze nooit een dam zullen bouwen. Dammen worden gebouwd om de ingang van het hol onder water te zetten (dit doen bevers om de ingang van hun hol/burcht te beveiligen) of om de waterstand te verhogen zodat er naar extra voedsel gezwommen kan worden.

De dam afbreken kan in specifieke gevallen als de Vlaamse overheid een afwijking op de beschermingsbepalingen toestaat. Maar het is geen duurzame oplossing. De kans is heel groot dat de bever op exact dezelfde plaats opnieuw een dam bouwt. Momenteel zijn er gemengde resultaten met het aanbrengen van een buis door de beverdam die het waterpeil terug naar een aanvaardbaar compromisniveau brengt voor bever en ander landgebruik. In de Verenigde staten is deze maatregel meestal succesvol. In Vlaanderen, waar er nog maar enkele jaren ervaring is met bevers, zijn de resultaten veel wisselvalliger. Een verdieping van de waterloop ter hoogte van het hol zou een mogelijke oplossing kunnen zijn, maar werd voorlopig nog niet getest.

In uiterste gevallen kunnen bevers, nadat alle schadevoorkomende en -beperkende maatregelen genomen zijn, en na toestemming van het Agentschap voor Natuur en Bos, verplaatst worden. Ook dit is geen duurzame oplossing. Bevers zijn territoriaal, en zodra er een territorium vrijkomt zal dit binnen korte tijd ingenomen worden door een nieuwe beverfamilie. Structurele maatregelen nemen om samenleven mogelijk te maken is daarom de beste oplossing.

Mogelijke problemen kunnen dus meestal (eenvoudig) opgelost worden, en we mogen blij zijn met de terugkeer van dit grote zoogdier.

Zelf beversporen gezien? Geef het door via www.waarnemingen.be

Tekst: Hendrik Moeremans, Natuurpunt
Foto: Eric Malfait

Meer over de bever

Over schadepreventiemaatregelen en eventuele schadevergoedingen: www.natuuralsgoedebuur.be (website van de Vlaamse overheid, Agentschap voor Natuur en Bos)

Artikel Unisversiteit Antwerpen: Swinnen, K.R.R., Strubbe, D., Matthysen, E. en Leirs, H. (2017) Reintroduced Eurasian beavers (Castor fiber): colonization and range expansion across human-dominated landscapes. Biodiversity and Conservation. doi:10.1007/s10531-017-1333-9

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Een studie van de Universiteit Antwerpen toont dat er in Vlaanderen voldoende leefgebied is voor meer dan 900 beverfamilies, ruim 7 keer meer dan er vandaag leven. Die vestiging zal in de praktijk niet altijd zonder uitdagingen verlopen, want de bever is een echte landschapsarchitect.

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2. The map butterfly (Araschnia levana) 

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2. The map butterfly (Araschnia levana) 

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Araschnia levana inhabits forests, parks and bushy to wooded wetlands. The adults usually occur only as nectar guests in open areas such as limestone grasslands. The caterpillar lives on partly to fully shaded nettles. Seasonal dimorphism. Both sexes of the spring brood are bright orange, marked with black spots. In contrast the summer generation adults are black with white spots and bands. Araschnia levana is common almost everywhere in Central Europe. One important cause may be the rapid spread of nettle due to eutrophication.

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Map, Araschnia levana - Butterflies - NatureGate

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Different generations of map butterflies look quite different from each other, almost like different species. The black end-of-summer form resembles the poplar admiral and purple emperor, but is significantly smaller. The yellowish orange spring form is recognisable by the blue braid on its hind wings.

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Predator-prey relations refer to the interactions between two species where one species is the hunted food source for the other.

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1. Kingfisher (Alcedo atthis) and Three-spined stickleback (Gasterosteus aculeatus)

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1. Kingfisher (Alcedo atthis) and Three-spined stickleback (Gasterosteus aculeatus)

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Kingfisher eats fish (fand aquatic insects).

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Kingfisher Bird Facts | Alcedo Atthis - The RSPB

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These distinctive birds are often seen as a blue flash whilst hunting for fish. They're small, bright blue and orange birds of slow moving or still water

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Variable diet: In its different forms or stages of life, the three-spined stickleback can be a bottom-feeder (most commonly chironomid larvae) or a planktonic feeder in lakes or in the ocean; it can also consume terrestrial prey fallen to the surface. It can cannibalize eggs and fry.

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The three-spined stickleback is found only in the Northern Hemisphere, where it usually inhabits coastal waters or freshwater bodies. It can live in either fresh, brackish, or salt water. It prefers slow-flowing water with areas of emerging vegetation. It can be found in ditches, ponds, lakes, backwaters, quiet rivers, sheltered bays, marshes, and harbours.

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2. Eurasian Hobby (Falco subbuteo) and dragonflies e.g. Banded Demoiselle (Calopteryx splendens)

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2. Eurasian Hobby (Falco subbuteo) and dragonflies e.g. Banded Demoiselle (Calopteryx splendens)

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Hobbies are often found near water. Enough food (birds, large insects) is also important.

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Hobby eats caught dragonflies / Boomvalk eet gevangen libellen (Falco Subbuteo)

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It is very sensitive to pollution so a good indicator of clean water. Mainly, adult dragonflies eat other flying insects, particularly midges and mosquitoes.

Immature damselflies, called larvae (or sometimes nymphs or naiads), are, aquatic predators. They eat almost anything living that is smaller than themselves.

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This species is widely distributed throughout VC 55 and is found along all of the main rivers and streams, and on all canals. Records indicate that it has always been a common damselfly in VC 55. The Banded Demoiselle favours slow flowing rivers and streams with muddy bottoms.

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The big jump of the Banded demoiselle in the area

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The big jump of the Banded demoiselle in the area

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Remarkable is the recovery of the Weidebeekjuffer in the Dijle Valley. The species was not noticed between 1985 and 1990. Since the second half of the 90s, however, the number is on the rise.

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natuur nieuws actueel natuurberichten natuurnieuws libellen

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Nature Today | De Big Jump van de Weidebeekjuffer

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Het is niet altijd kommer en kwel: met het gros van de libellen gaat het goed. En zeker met de Weidebeekjuffer. Die maakte de voorbije 20 jaar in grote delen van Vlaanderen een heuse comeback. Tijd om even stil te staan bij dit prachtbeest, net voor we dit weekend massaal het water in springen.

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Parasitism describes a relationship between two species, a parasite and its host, in which the parasite benefits, while the host is harmed.

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1. Greater Yellow Rattle (Rhinanthus angustifolius) - Grote ratelaar

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1. Greater Yellow Rattle (Rhinanthus angustifolius) - Grote ratelaar

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Yellow-rattle is an annual that thrives in grasslands, living a semi-parasitic life by feeding off the nutrients in the roots of nearby grasses. For this reason, it is seen as an indicator of poor grassland.

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Yellow rattle: the meadow-maker's helper

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Creating a mini-meadow in your garden is labour-intensive, but there is a plant that can help, says Andy Byfield of Plantlife

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2. Judas's Ear (Auricularia auricula-judae)

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2. Judas's Ear (Auricularia auricula-judae)

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It favours older branches, where it feeds as a saprophyte (on dead wood) or a weak parasite (on living wood), and it causes white rot.

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Auricularia auricula-judae ( Latin for 'Judas's Ear'), known as the Jew's ear, (black) wood ear , jelly ear or by a number of other common names, is a species of edible Auriculariales fungus found worldwide. The fruiting body is distinguished by its noticeably ear-like shape and brown colouration; it grows upon wood, especially elder.

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Judas's Ear: more and more people see it

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Judas's Ear: more and more people see it

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The fruiting body is distinguished by its noticeably ear-like shape and brown colouration. The increase can be attributed to several causes, but the increasing eutrophication of the last decades is seen as the main cause.

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natuur nieuws actueel natuurberichten natuurnieuws paddenstoelen vroege waarneming duinen hakhout bos wegbermen zandgrond droogte bijzonder verhaal tuinen

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Nature Today | Judasoren bij droogte onherkenbaar

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De afgelopen weken werden er judasoren waargenomen, maar door de droogte in een allerbelabberdste toestand. Ze waren verschrompeld, hard, dun en verkleurd en daardoor nauwelijks te herkennen. Nu er een regenfront passeert kun je goed zien hoe veerkrachtig judasoren zijn. Binnen korte tijd hebben ze hun oorspronkelijke vorm en kleur terug en neemt de sporenproductie weer een aanvang.

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Niche partition or the art of sharing.
Species can differentiate their niches in many ways, such as by consuming different foods, or using different parts of the environment.

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Great white egret (Ardea alba) - Grote zilverreiger

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Great white egret (Ardea alba) - Grote zilverreiger

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What they eat is fish, insects and frogs, caught by spearing with its long, sharp beak.
The species breeds in colonies in trees close to large lakes.

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Great White Egret Facts | Ardea alba - The RSPB

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As the name suggests, a large, white heron. Great white egrets can look similar to little egrets, but they are much larger, the same size as the grey heron

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The bird feeds mainly on fish, but also small crustaceans, insects small frogs.
It is an excellent swimmer and diver, and pursues its fish prey underwater.
Like all grebes, it nests on the water's edge, since its legs are set relatively far back and it is thus unable to walk very well.

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Great Crested Grebe Facts | Podiceps Cristatus - The RSPB

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A delightful, elegant waterbird with ornate head plumes which led to its being hunted for its feathers, almost leading to its extermination in the UK. Read more

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Great Crested Grebe and Great white egret both eat fish in the same area but they behave differently to catch them.
They eat some ather animals too.

Source Wikipedia:
The Great Egret feeds in shallow water or drier habitats, feeding mainly on fish, frogs, small mammals, and occasionally small reptiles and insects, spearing them with its long, sharp bill most of the time by standing still and allowing the prey to come within its striking distance of its bill, which it uses as a spear. It often waits motionless for prey, or slowly stalks its victim.
The Great Crested Grebe feeds mainly on fish, but also small crustaceans, insects small frogs and newts.

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Grote Zilverreiger - Ardea alba 2018-11-23 Neerijse - Doode Bemde - Kliniekvijvers

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Grote Zilverreiger - Ardea alba 2018-11-23 Neerijse - Doode Bemde - Kliniekvijvers

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Alexandre Sousa (Pt)Evaluation of this Padlet

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Alexandre Sousa (Pt)Evaluation of this Padlet

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