(Top) Diagram of evolution from reptiles to birds over time, (Bottom) Images of Darwin’s finches and their differing beak sizes which allow them to flourish under certain environmental conditions
Hopefully, you’ve learned a lot more than you previously knew about the evolutionary history of birds. But what makes a bird, a bird? When one thinks of a bird, they think of flight, they think of nests, and they think of little birds hatching out of eggs and progressively learning to fly. While these are all common characteristics of birds, not all of them fit the status quo. All birds can be categorized based on their habitats, diets, and behaviors, all of which differ from species to species. They are also warm-blooded vertebrates and all belong to the class Aves, characterized by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a strong yet lightweight skeleton. For example, certain birds such as the brown-headed cowbird don’t make nests at all, in fact, they lays their eggs in the nests of other birds, killing the other species in the nest in the process. Many birds outside of the United States also have extremely unique characteristics, not present in any other bird. For example, the Vogelkop superb bird of paradise from New Guinea was discovered in 2018. Similar to the “smiley face” bird of paradise, the Volgekop has a unique mating display in which it expands its black feathers into a round, frill—like shape that resembles a smiley face in conjunction with its space, blue coloration, similar to the dilophosaurus that releases venom by opening its frill. These are just two examples of the wonders of avian creatures. This goes to show that even though many birds have similar characteristics such as flight and laying eggs, it is what makes them unique that acts as the distinguishing factor.