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Source #5 and Source #3 agree on on not only the importance of natural preserves, but also the necessity of preserving the local vegetation to sustain the birds in the ecosystem. Both studied concluded that migratory bird species richness is highly dependent on maintaining the local ecosystem, however Source #5 adds a nuance to this claim. Its data suggests that rather than the nearby urbanization harming the bird populations, the development is necessary as it allows a higher maintenance of local vegetation, which in turn is often the food source of migratory birds.

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Although the study is located in an arid climate, Source #6 remains in agreement with the earlier sources and concludes that the migratory birds are more likely to thrive in areas with local vegetation present on the house property. The study goes even further, demonstrating that houses with changed terrain to match the outdoor environment had a comparable increase in bird species richness. However, Source #4 disagrees with this major alteration, stating that a uniform community-wide effort with minor changes (such as introduction of vegetation) is as effective as a few major changes.

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Source #12 and #13 both contain discoveries that demonstrate how migratory birds, along with other organisms, can create new stable ecosystems in cities during that adaptation of the new environment. Both studies also point out, however, that these new ecological connections the migratory birds make can result in greater harm. As Source #13 states, cities are rapidly changing, and therefore an ecological disruption can have a severe impact on multiple organisms in the urban ecosystems, as Source #12 states for migratory birds. Such rapid ecological change often results in a severe loss of biodiversity as Source #13 discusses, which the study discovered then leads to a lower possibility of adaptation and causing a vicious cycle of biodiversity loss for the organism.

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Source #8 and Source #9 are studies that both suggest migratory birds species richness can be preserved through a large-scale effort for slight modifications of common parts of infrastructure. Unlike the green roofs in Source #9, which discussed adding natural features to the buildings, Source #8 calls for the removal of large glass sections on buildings. The difference between the modifications in these two solutions is because the green roofs would provide potential habitats to migratory birds, whereas the large amounts of glass in many city buildings causes many migratory bird deaths.

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Source #3 - Effects of Land Cover Pattern Along Urban-Rural Gradient on Bird Diversity in Wetlands

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Source #3 - Effects of Land Cover Pattern Along Urban-Rural Gradient on Bird Diversity in Wetlands

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Purpose: To investigate the relationship between the land cover pattern along the urban-rural gradient and alpha (diversity within a biome) and beta (diversity comparison between two biomes) diversity of birds

Results:
- The researchers noted that the wetland birds in suburban and urban areas were mostly homogenous organisms
- The land patterns differed quite a lot between the two regions and caused a decrease of bird species richness while going down the rural-urban gradient
- The proportions of built lands acreage, submerged plants acreage, pond acreage, and edge density of emergent plants influenced the biodiversity a lot

Quotes:
- "We observed that the higher degree of connectivity between wetland habitats might be an important factor affecting the richness of the birds. In other studies researchers considered habitat density (suitable habitat at 1.5 km or less ) to be an essential predictor of wetland shorebird density and abundance, while migrant bird populations have been shown to increase significantly with the amount of suitable habitat in the landscape surrounding stopover sites”
- “For birds living in wetlands around the city, larger ponds and more extensive areas of aquatic plants may provide more spaces for nesting, shelters, and foods. Water birds need aquatic plants not only as a food source but also for shelter, especially those very sensitive to human disturbances such as Anatidae, some Scolopacidae, and Charadriidae birds. They rely on a more substantial buffer area of emergent plants as a shelter.”

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Sources #2, #8, and #9 work together to form a multi-pronged solution that, although it requires more modifications to existing infrastructure, are necessary in order to prevent further migratory bird population decline in cities. If such preventative steps are to be taken, migratory birds species richness can be preserved. Even though in some cases the migratory birds won't remain completely migrational, Source #10 demonstrates that these modifications will allow the species to have a healthy transition to a more sedentary lifestyle, thus resulting in preservation of the birds either way.

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Source #10 - Loss of migration and urbanization in birds: a case study of the blackbird (Turdus merula)

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Source #10 - Loss of migration and urbanization in birds: a case study of the blackbird (Turdus merula)

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Purpose: To check if partial migration (when a fraction of the population migrates and the other remains sedentary) may facilitate urbanization (of the blackbirds) because such populations benefit from surplus food in urban environments during winter, and hence enjoy reduced fitness costs of migratory deaths in the case of the European blackbird.

Results:
- Urbanization occurred earlier in partially migratory and resident populations than in migratory populations of blackbirds
- This effect was most pronounced in the range of the distribution that currently has the highest population density, suggesting that urbanization facilitated population growth
- These findings are consistent with the hypothesis that timing of urbanization is facilitated by partial migration, resulting in subsequent residency and population growth

Quotes:
- “...year of urbanization showed significant spatial auto-correlation at a scale of 600 km and migration status and population density at a scale of 1,200 km. We included these patterns of spatial auto-correlation in analyses of the timing of urbanization, showing that migration pattern and population density explained significant variation in when different populations became urbanized. Change from migration to partial migration and residency was consistently associated with year of urbanization. The auto-regressive term for year urbanized was an important predictor of year of urbanization, showing that a spatially explicit model provides better and more detailed information than a model without this spatial effect.”
- “Partially migratory populations of the blackbird started to winter in urban habitats following decades of some of these wintering individuals staying to reproduce during summer. In several cases, wintering blackbirds in specific sites became residents in exactly the same sites (see "Introduction"). such a transition was associated with exploitation of food found near human habitation or provided by humans (Dyrcz 1963; Pulliainen 1963) and reduced fear responses (Mpller 2010; Diaz et al. 2013). Similar patterns were observed for mallard, greenfinch and blue tit ”

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Source #13 - Urban evolution: How species adapt to survive in cities

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Source #13 - Urban evolution: How species adapt to survive in cities

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Purpose: To discuss the similarities and differences in the various ways animal, insect, and plant species have adapted to urban environments in cities.

Results:
- Nature still surrounds us → it’s just in a different form

- The rapid evolution, high temperatures, and pollution in cities makes them ideal environments to study nature’s response to global warming
- Ex: Peppered moth darkening its wings during the.  Industrial Revolution

- The evolution is so rapid that different neighborhoods have drastic differences in the same organisms

- Phenotypic plasticity (temporary adjustments) vs. Genetic adaptations (evolution) → Over time the best changes are the genetic adaptations

- Plays off of idea of nature (phenotypic plasticity) vs. nurture (genetic adaptation)

- Evolution changes organisms drastically compared to their natural counterparts → they have a completely different food chain (of which humans are a huge part)

- Water fleas = smaller and reproduce quicker in cities as opposed to the ones that live in rural ponds (phenotypic plasticity as they aren’t genetically different) + heat tolerance

Quotes:
- “Brown rats in Manhattan offer yet another case of urban evolution, though it may not impart advantages to the unloved creatures. Jason Munshi-South, an evolutionary ecologist at Fordham University in New York, and colleagues analyzed the genomes of 262 rats and found that the animals have evolved distinct genomic profiles in different neighborhoods. The scientists believe it’s because the rat populations don’t move freely between the spots, and slowly, over time, accrue differences…Midtown Manhattan may act as a kind of soft barrier…because it is less residential (providing less food).”
- “Unfortunately, the genetic biodiversity that can fuel adaptation often dwindles in urban areas. A genetic survey by Chloe Schmidt working in Garroway’s lab, food example, found this to be the case, along with lower population sizes, for North American mammals living in more disturbed environments. That’s a concern during a period when so many populations of animals and plants are seeing their natural habitats degraded or simply destroyed”

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Source #12 - Environmental factors shaping the distribution of common wintering waterbirds in a lake ecosystem with developed shoreline

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Source #12 - Environmental factors shaping the distribution of common wintering waterbirds in a lake ecosystem with developed shoreline

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Purpose: To provide information on the use of artificial cavities and artificial substrates in urban and human-altered areas for cavity-nesting birds.

Results:
- We recorded 16 cavity-adopter species using artificial cavities and 8 cavity-excavator species using artificial substrates for nesting

- Cavity-adopters used 11 different types of artificial cavities or substrates for nesting & Cavity-excavators used 6 types of artificial substrates for building cavities or nesting

- The most common substrates used by cavity-adopters were building roofs and wooden utility poles vs. For cavity-excavators, the most frequent substrates in use were utility poles

- 20.2% of the 94 Costa Rican bird species that are known to nest in wooden cavities and 9.5% of the 21 known dirt or burrow cavity nesters use artificial cavities or human-made substrates for nesting

- Urbanization of natural and semi-natural environments eliminates most of the natural nesting sites for cavity-nesters → dead trees and other natural substrates used by these birds are considered unsafe or non-aesthetic

Quotes:
- “The elimination of natural substrates should strongly reduce the abundance of cavity-excavators in urban areas compared to less urbanized and natural areas because the abundance of suitable substrates for nesting is limited (Protti-Sanchez and Sandoval 2019, Reynolds et al. 2019). Consequently, the reduction in cavity-excavators such as woodpeckers should directly impact the abundance of cavity-adopters such as tityras, flycatchers, and owls”
- “The reduction of natural substrates and excavated cavities in urban habitats seems to be the main reason why excavators use utility wooden poles and styrofoam eaves and cavity-adopters use metallic pipes or building roofs for nesting...However, the removal of substrates that provide natural cavities (e.g., dirt, rock walls, banks, dead trees, or branches) in urban areas could be the main reason why these birds use artificial cavities or substrates such as C-purlins (metal bars used as beams or as part of a building's frame), metallic pipes and boxes, or plastic pipes. These artificial cavities and substrates may compensate for the reduction of natural ones and maintain the populations of the cavity-adopter species in urban areas”

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Source #7 - Bird Migration Advances More Strongly in Urban Environments

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Source #7 - Bird Migration Advances More Strongly in Urban Environments

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Purpose: This study aimed to analyze the effects of urbanization by comparing the mean arrival dates and first arrival trends between urban areas and rural areas.

Results:
- The data in the common years (when all of the 18 species migrated) showed that the birds migrated 3 days earlier to the rural areas as compared to the urban areas
- There was a negative correlation observed between the mean FAD and the standard deviation of the FADs over the years
- The shorter-migration birds migrated earlier than the long-distance migratory birds (who were also noted to be losing population quicker and more sensitive to environmental change) by an average of 29 days in rural areas and 31 days in urban areas (overall data showed urban FADs were more variable than the rural FADs)

Quote 1

“However, the most interesting finding is that urban birds have recently advanced their arrival dates more than rural ones. This raises speculation as to the reasons, and suggests that a more in-depth study may be justified. Our study indicates that urbanization may significantly affect the phenology of these particular bird species, and consequently probably also the general biodiversity in cities. Furthermore, because of rapid urbanization worldwide and certain similarities in environmental effects between urbanization and climate change [3], [9], we believe that our findings may have a much wider relevance”

Quote 2

“Similarly, we find only limited evidence that migration distance influences the pattern of urban and rural advances. Generally, populations of long-distance migrants are declining more rapidly than short-distance and resident species, and may be more vulnerable or more exposed to environmental change [4]-[6], [21], [23]. Moreover, in cities some species that are migratory in rural habitats now show a strong tendency to be sedentary in urban habitats”

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Although organisms are eventually able to adapt to changes caused by urbanization through natural selection, inaction is an insufficient technique for ensuring the survival of migratory birds as the process of urban evolution results in a large loss of bird species richness.

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TRANSITION: CONNECTION FROM CLAIM TO CLAIM

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TRANSITION: CONNECTION FROM CLAIM TO CLAIM

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Cities have a much higher level of urbanization than suburban areas, which means a unified effort, as is needed in suburban areas, would be very difficult to manage. However, the uniformity of almost all cities leads to certain solutions being crafted from efficiently making small modifications to existing city infrastructure.

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The most effective method of preserving the species richness and abundance of migratory birds in peri-urban, suburban, and urban areas, involve human modification of existing land and infrastructure.

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With urbanization destroying ecological stability for migratory birds in not only urban areas, but also suburban and peri-urban areas, an effective solution has to be implemented. As these different regions have different levels of urban development, the risks they pose to migratory birds as well as the optimal solutions to counteract the danger vary. The presence of undeveloped natural land in peri-urban regions allows for the optimal course of action to be creating natural preserves in order to maintain the natural habitat for the birds. In the case of the more urbanized suburban and urban regions, modification of existing land and infrastructure is necessary as they don't possess the undeveloped land found in peri-urban areas. While suburban areas require small-scale modification to front and back yards to imitate the birds' natural habitat, urban areas require more severe alterations by creating green roofs as well as minimizing harmful glass structures. Despite the possibility of nature allowing the birds to evolve to their new environments independently, human action through alteration of land is required as nature's course of action poses a large possibility of decreasing biodiversity and population size as byproducts.

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Source #1 discusses about the negative impact of intense agriculture on the species richness of migratory birds, suggesting that partially preserving nature isn't an effective method. Instead, absolute preservation, which signifies no urban activity within the area, is much more effective at preserving bird species. Source #7 builds off of this idea, stating that migratory birds accustomed to completely natural stopping points, especially species who migrate longer distances, are more sensitive to urbanization. Strictly maintaining a natural preserve without any harmful urbanization is therefore necessary for the protection of these sensitive species.

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TRANSITION: CONNECTION FROM CLAIM TO CLAIM

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TRANSITION: CONNECTION FROM CLAIM TO CLAIM

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Despite the suggested modifications in urban, suburban, and peri-urban areas being proven successful preservation techniques, these steps are hard to coordinate and conduct. Urbanization, while being an indication of development, also correlates to an increase in time, finance, and effort required and thus is considered by some to be an inefficient preservation method.

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TRANSITION: CONNECTION FROM CLAIM TO CLAIM

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TRANSITION: CONNECTION FROM CLAIM TO CLAIM

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Although peri-urban areas only have a small amount of urbanization, suburban areas are a result of a higher level of urbanization and destruction of natural habitats, signifying that more severe steps need to be taken for preservation of migratory birds.

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Suburban areas are different from the peri-urban regions primarily due to lack of creating natural preserves due to most land being developed to a certain extent. Despite this constraint, residents are able to utilize their front and back yards to imitate the natural environment in order to preserve the migratory bird species richness, as the natural preserves do. These changes need not be of a large magnitude, as one of the sources states that many residents making small changes, preferably by introducing local vegetation, would be the optimal course of action for preservation.

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Source #2 and Source #9 mostly agree with each other as they both suggest a strong positive relationship between greenery and the species richness of migratory birds in cities. The two sources differ, however, in terms of the optimal usage of the preservation techniques evaluated in the sources. Source #2 advocates for green spaces, plots of lands that are kept undeveloped in cities, which are only possible to be created in newer cities that still have such undeveloped land. As for older cities, which are less likely to have undeveloped plots of land, Source #9 suggests a much better solution of modifying existing infrastructure and creating green roofs for preservation.

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Source #4 - Having our yards and sharing them too: the collective effects of yards on native bird species in an urban landscape

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Source #4 - Having our yards and sharing them too: the collective effects of yards on native bird species in an urban landscape

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Purpose: Identify the relative importance of yard design and management for native birds and their species richness. Furthermore, the researchers wanted to investigate how different types of birds (migratory, all-year habitants, and nonnative) are influenced by yards.

Results:
- Rather than specific environmental characteristics or the size of the yard, the presence of an aggregate of neighboring yards was more important for species richness
- While local cat populations decreased species richness, the number of bird feeders surprisingly had no correlation, and migratory birds increased with the number of wildlife-friendly features in the yards

Quotes:
- “Migratory birds were also found on transects with the fewest outdoor cats (mean = 3.2 cats per transect; 5.1 for (exotic birds) and fewest dogs (mean = 24.4 dogs per transect; 30.3 for exotic birds). There were no significant differences between species groups for bird feeders, tree-shrub interaction term, or insecticide use”
- “Our results suggest that urban conservation agendas would benefit from ‘thinking outside the park’ (Marzluff and Rodewald 2008) and highlighting to residents the positive collective effects of minor yard enhancements. Recent research indicates that people are more interested in taking actions when the positive aggregated effects of small behavioral changes are highlighted (Dickinson et al. 2013)”

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All three sources suggest mostly the same idea regarding the success and safety of allowing migratory birds to naturally adapt to highly urbanized environments. As Source #13 primarily explains, organisms such as migratory birds are able to adapt to urban environments through natural selection. However, leaving this process up to nature is very risky for urban bird species richness and population abundance as without human action, Sources #11 and #13 suggest evolution only happens optimally under certain conditions. Finding a city fulfilling multiple requirements is a rare occurrence, and thus human action is necessary for efficient preservation of migratory birds.

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Both Source #11 and Source #12 indicate that migratory birds are able to adapt to the new habit of an urban city, however they both also specify that such a transition only occurs for some species under specific favorable conditions. Source #11 indicates that cities in humid climates are better at retaining population abundance as opposed to cities in arid climates. Similarly, Source #12 suggests that although cavity-excavator species are able to adapt, they require the city to have certain substances like wood for the birds to safely create nests and transition to the urbanization. Such specificity of conditions indicates that a lack of action, despite its possibility of success, is a risky course of action in which the migratory bird species richness could decrease dangerously in cities.

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Source #10's discovery that many blackbird populations are healthily able to transition to a partially migrating or completely sedentary species is the effect of preservation techniques such as the one in Source #8. In fact, due to multiple preservation techniques, including green roofs and green spaces, many European cities saw the abundance of many blackbird populations increasing as they increasingly urbanized.

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All of these sources indicate that urbanization to a certain extent does negatively impact the highly-sensitive migratory birds, who require their natural environment in order to survive. However, severe modification of peri-urban land isn't required to counteract the harm done by urbanization. Instead, the sources suggest, the only required course of action is to preserve any untouched natural environment (which is usually located in these less urbanized peri-urban areas) in natural preserves as the migratory birds rely the most on an unchanged environment, not necessarily a larger preserve. It is logical to assume that an additional step is to reduce the urbanization in areas surrounding the natural preserves, however, Source #5 states that the nearby urbanization is actually more helpful than harmful. The developed urban areas are correlated with a sufficient amount of resources being invested in maintaining the natural preserves, which ensures the migratory birds have a a better habitat and thus are able to survive.

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While Source #1 explains the flaw of considering croplands natural preserves as farming is a form of urbanization, Source #3 explains how natural preserves should be created. It emphasizes the importance of local vegetation, which many organisms utilize in ecosystems, especially migratory birds, as not only a source of energy, but also as a shelter. Extending on the argument that there's a need for natural preserves outlined by Source #1, Source #3 outlines the necessity of vegetation in order to maintain a preserve sufficient to sustain migratory birds.

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How can the land use in urbanized regions be altered to best preserve migratory birds from the dangers of urbanization?

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Source #2 - Diversity of Bird Species in Urban Green Spaces of Davao City, Mindanao, Philippines

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Source #2 - Diversity of Bird Species in Urban Green Spaces of Davao City, Mindanao, Philippines

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Purpose: To gather bird species diversity data for the 15 urban green spaces in Davao City in the Philippines. There was also a secondary purpose to determine the correlation between the size of the green spaces and its Shannon diversity values (an index to measure the evenness in the abundance of a species).

Results:
- There were 53 species observed, of which only four species were common in all sites
- The Shannon diversity values varied across sites
- Statistical analysis revealed a positive correlation (r = 0.54) with green space size

Quotes:
- “Reports of a few studies in the Philippines reveal that bird species benefit from available habitats provided by urban green spaces…urban green spaces in Metropolitan Manila served as a refuge for migrant birds. Endemic species were also recorded in several urban green spaces of the country”
- “Endemism was also noted to be low across all urban green spaces surveyed. This conformed to earlier reports of avifaunal composition in other urban green spaces of the country (Ong et al. 1999; Posa and Sodhi 2006; Vallejo et al. 2008, 2009; Medina and Cabras 2018; Serrano et al. 2019; Yurong et al. 2020). The degree of bird endemism in a landscape is attributed to vegetation type. Tanalgo and colleagues (2019) mentioned that intact native forests are valuable habitats for endemic birds…Since green spaces surveyed were minimally composed of native plant species at the time of sampling; thus, low endemism was noted”

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Source #9 - Urban green roofs provide habitat for migrating and breeding birds and their arthropod prey

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Source #9 - Urban green roofs provide habitat for migrating and breeding birds and their arthropod prey

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Purpose: To evaluate the effectiveness of green roofs, special roofs covered partially or entirely with vegetation, in urban areas as potential habitats for migratory birds.

Results (Images)

Quote 1

“The benefit of green roofs to birds is, in part, because green roofs can provide habitat for arthropods which are an important element of quality habitat for most birds [74–78]. Our study demonstrates the higher value of green roofs as arthropod habitat compared to conventional roofs. While conventional roofs can provide arthropod habitat when vegetation colonizes portions of the roof [114–116], we show that green roofs host a higher abundance and richness of arthropods”

Quote 2

“Migrating birds that pass through urban landscapes can use urban green space to adequately refill fat stores during stopovers [29, 126], and the birds we recorded during spring migration were likely using urban green roofs as stopover habitat. Migrating birds will move short distances to more suitable habitats shortly after landing in a stopover habitat [35, 127, 128], and migrating birds using urban green space as stopover habitat demonstrate high levels of movement within the first day of arriving [44, 129]. While we recorded migrating birds stopping over on green roofs, the abundance of such birds was limited, which could indicate that green roofs are insufficient habitat for prolonged stopovers [130]. Another interpretation of this limited abundance of migrating birds on our green roofs could also indicate that green roofs are the only stopover habitat available to migrants [131] or that green roofs are being used as temporary habitats between nocturnal flights”

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Source #8 - Factors influencing bird-building collisions in the downtown area of a major North American city

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Source #8 - Factors influencing bird-building collisions in the downtown area of a major North American city

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Purpose: To identify the factors that influence bird-building collisions in an American urban setting and their specific relationship (direct, inverse, etc.) with bird mortality.

Results:
- Four of the buildings (including the stadium) caused a higher number of collisions, which the analysis related to the increased amount of glass area and surrounding vegetation
- Looking at the overall data for most of the buildings, however, there was no one single factor that had a statistically significant correlation with the number of collisions
- The season (spring or fall), which relates to the bird species, did vary directly with the collisions

Quote 1

“Nonetheless, given research showing that large, glassy buildings nearly always cause large numbers of bird collisions, we expect that similar glassy stadiums would also cause substantial collision mortality. Even less-glassy stadiums with extensive lighting may cause numerous collisions because intense nighttime lighting confuses nocturnally migrating birds, altering their flight paths, bringing them closer to the ground, and elevating collision risk [27]. Recognizing the risk posed to birds, there have been some efforts to incorporate bird-friendly design elements into new stadiums. For example, the Fiserv Forum basketball arena in Milwaukee, Wisconsin, was designed to reduce bird collisions by minimizing the use of reflective and see-through glass”

Quote 2

“The effect of glass area likely arises due to several factors, including greater confusion of birds due to larger amounts of reflective and/or see-through surfaces, especially in large unbroken expanses [52], and an increase in light emission increasing numbers of nocturnal migrants attracted to buildings (see lighting discussion below). The effect of vegetation likely occurs due to its attractiveness to birds as a source of food and cover, especially for migratory birds resting and refueling during stopovers in an otherwise heavily urbanized landscape. Vegetation may also exacerbate reflection effects; birds may be less able to perceive glass as a barrier when it reflects vegetation and/or more likely to fly toward glass if they perceive they are flying toward vegetation "

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Source #1 - Bird Assemblages in a Peri-Urban Landscape in Eastern India

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Source #1 - Bird Assemblages in a Peri-Urban Landscape in Eastern India

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Purpose: To analyze the effects of urbanization on bird diversity in a peri-urban landscape (a region in and/or surrounding a city).

Results:
- All the habitats differed significantly
- The cropland and residential were most comparable as were the forest and water bodies
- Cropland had the most number of species, the water bodies had the biggest avian population
- Winter brought the richest variety of species, but all habitats had the most similar species richness in the other two seasons

Quotes:

“Studies found that cropland is used as a stopover habitat by migratory bird species...However, in some cases, intensified agricultural production may affect farmland biodiversity. For example, after receiving new membership in the European Union, farmland bird diversity declined due to intensified agricultural activities in some European countries”

"We found that bird richness and abundance significantly varied across the season. The change in richness and abundance of birds depends on the presence of abundant species that visit the area in different seasons. Several studies argued that variations in rainfall and temperature affect the availability of food resources for birds and influence bird populations. Sometimes, the numbers of migratory birds are maximum compared to resident birds during the migratory season affecting the bird richness and abundance” - importance of migratory birds (for intro)

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Source #6 - The conservation value of residential yards: linking birds and people

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Source #6 - The conservation value of residential yards: linking birds and people

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Purpose: To identify the relationship between socioeconomic factors, landscape designs, and the urban gradient measurements within the bird communities in urban areas.

Results:
- Native desert bird abundance and population variation were greatly explained by the presence of yards near desert tracts, yards with desert designs, and high-income neighborhoods
- Furthermore, the satisfaction with the local bird biodiversity had a positive correlation with the actual bird biodiversity, showing people are aware of the bird biodiversity in their areas

Quotes:
- “By comparing the relative importance of local vegetation in residential yards with regional landscape features, our study found that the local habitat variables had twice the explanatory power relative to the regional landscape features to describe the patterns of the urban bird community”
- “Our socioeconomic redundancy analysis revealed strong environmental inequities; predominantly Hispanic and lower-income neighborhoods had few to no desert birds. These results are in accord with previous findings from Phoenix and from Vancouver, British Columbia, Canada, where plant and bird diversity increased with socioeconomic status...The presence of bird feeders have strong influences on residential yard bird communities and have been linked to socioeconomic factors

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Source #5 - The Value of Urban Forests to Wintering Birds

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Source #5 - The Value of Urban Forests to Wintering Birds

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Purpose: Evaluate if riparian (river banks) forest parks, which are surrounded by urban development (which improves the food resources in microclimates), would be able to support a larger number of migratory birds than similar forests in nearby rural landscapes.

Results:
-  The species richness and abundance had a strong correlation with the size of the forest and forest land usage
- Surprisingly, the species richness had the strongest correlation to the percent of urban development within a 1 km radius had the strongest correlation
- The urban development had a strong correlation with habitat characteristics such as ambient temperature and the number of bird feeders available

Quotes:
- “While other studies show that urban development negatively impacts many sensitive species (Smith and Schaefer 1992, Friesen et al. 1995, Rottenborn 1999) , our data suggest that urban development within the landscape surrounding riparian forests, at the same time, may improve conditions for some wintering birds. As urban development within the landscape increased, species richness, total abundance, and number of nine of 10 individual species increased within the forest stand”
- “Another possible explanation for the positive relationship between urban development and wintering birds is that urban development improved food resources by promoting the invasion of exotic plant species such as honeysuckle. Our habitat data indicated a positive association between urban development and understory stem density, which was largely due to the greater density of Lonicera in urban landscapes…exotic [plant’ species produce abundant fleshy fruits that may benefit certain [bird] species that are relatively frugivorous”

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Source #11 - Bird Diversity in Urban Ecosystems: The Role of the Biome and Land Use Along Urbanization Gradients

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Source #11 - Bird Diversity in Urban Ecosystems: The Role of the Biome and Land Use Along Urbanization Gradients

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Purpose: Whether the biomes where human settlements and land uses are developed, determine bird diversity along urbanization gradients in the southern Neotropics (from southern Mexico down to the coastal regions of Argentina)

Results:
- Species richness was positively correlated to vegetation cover in both human settlements
- In the city located in the arid biome, the highly developed area supported higher bird richness than the natural habitat, unlike the city from the humid biome
- Humid biome = the native bird assemblage was better preserved in the urban area established in the humid biome
- Richness in moderately developed areas was either higher than or similar to that in rural or natural areas in the settlement from the arid biome, but lower than or similar to richness in the humid biome
- We observed different spatial patterns of species richness from the highly developed to the non-urban areas between the settlements located in the humid and arid biomes; however, that was the result of total vegetation cover having a positive relationship with species richness in both settlements, which is indeed a general pattern

Quotes:
- “Furthermore, bird community composition in the highly and the moderately developed areas was more similar to community composition of the natural habitat in the humid biome than in the arid biome. This result is likely because the city in the humid biome conserves some elements of the natural forest, such as native trees, whereas the city in the arid biome has exotic trees and preserves few elements of the shrubland…yet, the native bird assemblage may be better preserved in urban areas established in humid biomes”
- “Third, the House sparrow and the Rock dove, both exotic to South America, are associated with highly developed areas where assemblages are composed of a few very abundant and worldwide distributed species (Chace and Walsh 2006) that nest on buildings and feed on the ground”

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Even though the effects of urbanization on migratory birds can't be eliminated, increasing the greenery and reducing harmful glass infrastructure can dampen the harm enough to maintain the bird population abundance.

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Suburban areas, which often lack the undeveloped areas needed for nature preserves, need to instead modify front yards and backyards in a unified effort to imitate the local environment to preserve the migratory bird species.

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Context + Introduction + Focus (Problem Statement)

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Context + Introduction + Focus (Problem Statement)

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For the approximately 1,800 bird species that are classified as migratory (U.S. Fish & Wildlife Service), home doesn't simply consist of one place as it does for sedentary bird species. Instead, migratory birds inhabit multiple stopover habitats on top of their normal home habitat, a trait which in the past few years has caused great harm to their kind. A multitude of studies, including the U.S. Fish & Wildlife Service, have observed that "Millions of acres of bird habitat are lost or degraded every year due to development, agriculture, and forestry practices...". More than converting land from its natural use, urbanization has also led to "millions of birds [to be] directly killed by human-caused sources such as collisions with man-made structures". (U.S. Fish & Wildlife Service). As migratory birds have many roles in multiple ecosystems as pest control, pollinators, and food source for predators, the massive death toll of urbanization has massive ecological implications. Even with such a strong call of action, a solution is difficult to create as the effects of urbanization differ depending on the level of urbanization. Peri-urban areas, which have very little urbanization, pose different risks than the more urbanized suburban and urban areas do.

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Peri-urban regions, which are less urbanized areas, can serve as optimal stopping points for migratory birds with very little change of land usage. If certain areas of land are strictly preserved as natural preserves and proximity to urbanization is maintained, migratory bird species can be protected from the small amount of urbanization.