What is a Bird?

Tarun Ramakrishnan

July 8, 2022

In this series of articles, I will be educating you about birds worldwide and taking a deeper dive into how they can help solve some of the world’s biggest problems. I hope you enjoy this series and learn more about birds!

I’m sure many of you read the title of this article and said, “Haha, I know what birds are, what more do I need to know about them?” Great question! For starters, the first birds to have been discovered belong to Archaeopteryx, a genus of bird-like dinosaurs living in the Late Jurassic period, about 150 million years ago in Southern Germany. The Archaeopteryx is known as the ancient link between non—avian reptiles and birds, the most plentiful group of avian mammals on Earth. Archaeopteryx was small in size, had broad wings, and could fly and glide, uncharacteristic of most dinosaurs in this period. However, arguably the most important characteristic of this species is the plethora of feathers on its surface, which hold significant importance to descendants of the species. Fossils of this specific species were identified just before Charles Darwin published his research in On Origin of Species, which proved that the Archaeopteryx set the stage for the evolution of birds.

`(Top) Fossil of Archaeopteryx lithographic displayed in Museum für Naturkunde in Berlin, (Bottom) Modern adaptation of the Archaeopteryx in Jurassic World: Dominion (Image Credit: Universal Pictures)

Now that we have covered a brief history of birds, let us explore the continued evolution of birds through the years. In On Origin of Species, Charles Darwin coined the term “natural selection”, which essentially meant that the individuals best suited to a particular environment would go on to survive and reproduce. Even though this theory contradicted others in its time, it made sense and was even tested in real life by Peter and Rosemary Grant in the Galapagos Islands. They observed how different species of finches dealt with certain conditions in their environment. For example, if small fruits and seeds were scarce, the finches with smaller and weaker beaks would die out while those with large beaks would flourish if medium — large seeds that had tough shells were plentiful. Natural selection still occurs today and ensures the survival of nature’s greatest birds, complete with traits and characteristics that enable them to dominate their environments and survive for many generations until natural selection erases them from the population.

(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.

(Top) Different beak types in bird species, (Bottom) pictures of the Volgekop bird of paradise during its mating display

In conclusion, birds have been around for millions of years and never cease to amaze enthusiasts all over the world. From their theropod ancestors to their unique species and characteristics, birds have evolved over time to produce millions of different species, each complete with their own habitats, behaviors, and unique characteristics that distinguish them from any other.