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-Waterproof skin covered in feathers

-Endothermic (warm blooded)

-Hard shelled eggs that are waterproof

-Beak or bill (no teeth)

-Bipedal (walk on two legs only)

-Wings
https://www.ck12.org/biology/bird-structure-and-function/lesson/Bird-Structure-and-Function-BIO/

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Birds eat high energy because they have a high metabolic rate. Birds also eat lightweight foods because they need a low body mass to be able to fly efficiently. Most food is swallowed whole and not chewed because of the bird’s beak/bill, instead of teeth. Although, they do have a gizzard in their digestive system to grind up the food.
https://www.coolgalapagos.com/animals/aves_birds.php

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It all starts with behavior aimed at attracting a mate. Birds will use a type of display, most likely performed by the male. Some displays are very elaborate. This can include dancing, aerial flights, or wing or tail drumming. Birds reproduce sexually through internal fertilization. After this happens, a hard- shelled egg will form inside the female.

https://www.ck12.org/biology/bird-reproduction/lesson/Bird-Reproduction-MS-LS/

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Birds protect their offspring by camouflaging their eggs, if their nests are located on the ground. Birds also can create different shaped nests and place them somewhere hidden to protect their offspring. Birds will also incubate their eggs by sitting directly on top of them, giving off heat.

https://www.ck12.org/biology/bird-reproduction/lesson/Bird-Reproduction-MS-LS/

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http://www.krugerpark.co.za/africa_fish_eagle.html

Habitat: Mostly found in Southern Africa in the Rift Valley Lakes. Located near lakes for abundant food supplies.

External: Large Eagle with black, white, and brown plumage, Yellow hooked shaped beak with a black tip

Internal:
-Gizzard- make up for the lack of teeth by grinding food, which can then be digested more quickly,
-Air Sacs- store inhaled air and push it into the lungs like bellows. This keeps the lungs constantly filled with oxygenated air
-Heart- large, four-chambered heart The heart beats rapidly to keep oxygenated blood flowing

tissueshttps://www.ck12.org/biology/bird-structure-and-function/lesson/Bird-Structure-and-Function-BIO/

Behavioral: Two distinct calls- in flight or perched. The call is very well known and often referred to as “The Voice of Africa”. Birds are usually in pairs, whether it is breeding season or not.

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https://animalcorner.co.uk/animals/golden-pheasant/

Habitat: Live in dense forests and woodlands

External:
Unique Coloring:
- golden crest tipped with red from the top of their heads to their necks
- bright red underparts,
-dark colored wings
-pale brown, long, barred tail
-green upper backs
-bright yellow eyes
-face, throat and chin are a rust color
- Beak, legs and feet are also yellow

Internal:
-Gizzard- make up for the lack of teeth by grinding food, which can then be digested more quickly,
-Air Sacs- store inhaled air and push it into the lungs like bellows This keeps the lungs constantly filled with oxygenated air
-Heart- large, four-chambered heart The heart beats rapidly to keep oxygenated blood flowing

https://www.ck12.org/biology/bird-structure-and-function/lesson/Bird-Structure-and-Function-BIO/

Behavioral: When a male is trying to mate he will spread his neck feathers over his head and beak, like a cape. Males also have a distinctive call during the mating season.

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https://www.allaboutbirds.org/guide/Red-headed_Woodpecker/id

Habitat: treerows in agricultural areas, and standing timber in beaver swamps and other wetlands

External: medium-sized woodpeckers with fairly large, rounded heads, short, stiff tails, and powerful, spike-like bills.The birds have bright-red heads, white underparts, and black backs with large white patches in the wings.

Internal:
-Gizzard- make up for the lack of teeth by grinding food, which can then be digested more quickly
-Air Sacs- store inhaled air and push it into the lungs like bellows. This keeps the lungs constantly filled with oxygenated air,
-Heart- large, four-chambered heart. The heart beats rapidly to keep oxygenated blood flowing

https://www.ck12.org/biology/bird-structure-and-function/lesson/Bird-Structure-and-Function-BIO/

Behavioral: The woodpeckers catch insects by hammering at wood. Also, they have raspy calls.

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Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: Ciconiiformes
Family: Acciptidae
Genus: Haliaeetus
Species: vocifer

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Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: Galliformes
Family: Phasianidae
Genus: Chrysolophus
Species: pictus

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Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: Piciformes
Family: Picidae
Genus: Melanerpes
Species: erythrocerphalus

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http://palaeo.gly.bris.ac.uk/Palaeofiles/Fossilgroups/aves2/patag.html

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Late Jurassic (150 million years ago)

Confirms the linkage between birds and reptiles as written in Charles Darwin’s “The Origin of Species” book.

Avian Characteristics:
-feathers
-wishbone
-wings

Reptilian Characteristics:
-long, bony tail
- hand with three separate clawed digits
-toothed jaw

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Early Cretaceous

-Horn beak
-pygostyle tail
-slightly keeled sternum

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Late Cretaceous

Avian characteristics: pygostyle tail.

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Late Cretaceous

Contains the long, bony reptilian tail, but shows advanced features in the hand.

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Late Cretaceous

Developed muscles to help improve flight mechanisms

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Cenozoic

Two toes facing forwards and two toes facing backwards, found in most perching birds

https://monarchbfly.com/2007/12/09/birds_toe_arrangement/

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Birds and dinosaurs evolved from a common ancestor. Evidence is shown through the similarities between the fossils, showing evidence of feathers and a wishbone in both birds and dinosaurs. The Archaeopteryx was a dinosaur with bird- like features, including a long bony tail and feathers. Currently, most birds have short bony tails, which shows the effects of evolution. During the cretaceous, birds evolved into all different shapes and sizes depending on their ecological niches. Also, the new features developed after the archaeopteryx, including wings and rib cages suggests the evolution of birds ability to fly.

https://nhm.org/site/research-collections/dinosaur-institute/dinosaurs/birds-late-evolution-dinosaurs

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Birds have diploid chromosomes ranging from 62-90. The closer the number of chromosomes a species has, the more likely the species are related. For example Tinamiformes have a range of 78-80 chromosomes, whereas the Pelecaniformes have a range of 66-70 chromosomes.

https://onlinelibrary.wiley.com/doi/epdf/10.1111/j.1601-5223.1981.tb01757.x

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Karyotypes can also be used to identify Class Aves. Birds karyotypes will look different from other organisms. For example birds sex chromosomes are Z and W, instead of X and Y. Also, the closer the bird karyotypes look, the more closely related the organisms will be.

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Ex: Anser anser

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Ex: Cygnopsis cygnoid

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The first karyotype is a male because there are two Z chromosomes and the second karyotype is a female because there is a Z and W chromosome. The two karyotypes are both bird species and can be identified by the size of each chromosome. The chromosomes gradually get smaller and in both karyotypes are almost the exact same size. Also, in both karyotypes the centromere is placed ¾ up on the chromosome.

https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1601-5223.1966.tb02056.x

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The early development of an organism can reveal evolutionary similarities. The closer the embryology of an organism, the more likely the organisms evolved from a common ancestor. An example of this is between fish, reptiles, birds, and humans. All four share the characteristics of gill slits and tails. This provides evidence of common ancestry.

https://www.ncbi.nlm.nih.gov/books/NBK10049/

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Homologous structures are those organs whose underlying similarity arises from their being derived from a common ancestral structure. A human arm, a seal forelimb, a bird wing, and a bat wing are homologous structures and the similarities are shown in the same colors. All four are homologous as forelimbs. The adaptations of bird and bat forelimbs to flight, however, evolved independently of each other. The bird and bat diverged from their common ancestor, while the wings developed Therefore, as wings they are not homologous, but analogous.

https://www.ncbi.nlm.nih.gov/books/NBK10049/figure/A72/?report=objectonly

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Punctuated Equilibrium is the hypothesis that evolutionary development is marked by isolated episodes of rapid speciation between long periods of little or no change. Class aves follows the punctuated equilibrium because the species have developed rapidly over long periods of time and not gradually. Evidence is shown by the Archaeopteryx. The Archaeopteryx is a dinosaur with bird- like features. The Archaeopteryx had claws, a bony tail and teeth, like a reptile. It also had feathers, a wishbone and a beak like a bird. It did not have any of those features partially formed. The new features, including a beak structure, appeared suddenly. The wishbone was a fusing of the collarbones and the bones of the archaeopteryx turned out hollow. These new characteristics developed rapidly and there is no evidence of other organisms having gradual changes that would lead to these new characteristics.

http://www.ideacenter.org/contentmgr/showdetails.php/id/1232

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Coevolution is he influence of closely associated species on each other in their evolution.

Birds and flowers have evolved together in two different ways. Some birds are nectar- eaters and at the same time pollinate the flowers. Also, birds can be fruit- eaters and at the same time disperse the seeds. In both of these instances, the two species are important to each other for their reproductive success and survival. This is most common in the tropics because there is more abundance of fruit plants.

https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1467-8748.1994.tb00440.x

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Seasonal migration is common in birds, as resources become scarce in the winter. As birds migrate, where resources are available, they have a better chance of survival and reproduction. An example of this is the Eagle, who nest in the northern United States and Canada. These birds migrate south in late autumn and early winter, when lakes and rivers in their nesting grounds freeze over. As resources are searched for, new migration patterns are made, which can lead to new breeding localities. Also, organisms whose movements gave them better chances to survive and reproduce will pass that migratory behavior along to their offspring. Which overtime, can lead to new climates and resources.

https://www.allaboutbirds.org/the-evolution-of-bird-migration/

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Adaptive radiation is the diversification of a group of organisms into forms filling different ecological niches. An example of this is when Charles Darwin studied finches on the Galapagos Islands. There ended up being at least 13 species of finches on the Islands, each filling a different niche. The birds developed different diets and the finches with the best adaptations or size/shape of their beaks reproduced. All of the birds evolved from one ancestral species, which then diversified into many.

http://www.pbs.org/wgbh/evolution/library/01/6/l_016_02.html

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Descent with modification is a result of adaptive radiation. This occurs when a population, in this case birds, are all slightly different from one another. Individual finches on the galapagos island can have phenotypic advantages to help them survive. When the birds reproduce, they will pass the phenotype traits to the next generation. Over time, the desired traits become more abundant as the birds continue to survive and reproduce.

http://www.fossilmuseum.net/Evolution/DarwinsFinches.htm

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Charles Darwin studied directional selection while he was in the Galapagos Islands. He discovered that the beak length of the finches on the island changed over time as available food sources changed. When there was a lack of insects to eat, finches with larger and deeper beaks survived. They survived because their beak structures were able to crack seeds, while other beaks couldn’t crack the seeds. Over time, as insects became more available and seeds became less abundant, directional selection began to favor finches with smaller and longer beaks because they could catch insects more efficiently.

https://www.thoughtco.com/types-of-natural-selection-directional-selection-1224581