Keep reading if you would like a ‘bird’s eye view’ of what defines our feathered friends. There are roughly 10,000 unique bird species in the world, and all birds are classified as members of the Kingdom Animalia, Phylum Chordata and Aves. This classification tells us that birds are related through many of the characteristics they share. Birds are distinguished from other animals by their feathers, hard-shelled eggs that they lay, toothless beaked jaws, a high metabolic rate, a four-chambered heart, and a strong yet lightweight skeleton that features hollow bones. Birds are the only living animals that have feathers, which are used as insulation from the cold. Birds lose and replace their worn or damaged feathers. Different types of feathers may also be ornamental, such as plumes, crests or streamers. Other feather types help birds control their flight, while some feathers, such as down, are strictly for insulation.
Birds are warm-blooded vertebrates. All birds have a backbone, which places them in the Phylum Chordata. Unlike most other vertebrates, birds have a lighter skeletal structure filled with hollows, gaps and air sacs to keep birds lightweight so they can fly more efficiently. All birds have two wings, which are one of the most defining characteristics of birds. Even flightless birds have vestigial or adapted wings or flippers they may use for swimming, threat displays or courtship dances. The size and shape of wings varies between species based on how the bird flies, and wing markings are useful to identify bird species.
All birds have a bony, keratin-covered projection forming their mouth called a bill. The words bill and beak are synonymous, but ornithologists tend to use the word ‘bill’ more often than ‘beak’. This bill is frequently evolved for specific bird diet types, and many birds also use their bills as tools for carrying, drumming, drilling, preening and other tasks. Some birds even use their bills as weapons or to help regulate body temperature. All birds are endothermic, which means they generate their own internal body heat and do not rely exclusively on their environment to maintain their temperature. Endothermic animals are referred to as being warm–blooded. Birds have a high, efficient metabolism that quickly turns food into usable energy. They have a four-chambered heart and high respiratory rate as well, which helps them be efficient and agile fliers as well as maintain their high body temperatures.
All birds have two legs (Bipedal) used for perching, walking, hopping or running. Different types of birds have evolved different leg shapes and lengths to suit their needs. Wading birds have thin, long legs suitable for moving through deeper water, while raptors (birds of prey) have thicker, more powerful legs that they use for capturing prey. Though it is not visible from the outside, every bird has a furcula, or wishbone, that protects the chest cavity during wing beats. This keeps the bird’s chest organs safe from excessive pressure as the wings move and birds change altitude, and its primary function is in the strengthening of the thoracic skeleton to withstand the rigors of flight.
All birds lay amniotic eggs (covered by an almost impervious shell which protects it and isolates it from the environment) as part of their reproductive cycle. The eggs have a hard shell and require incubation to continue development until hatching. Egg size, shape and markings varies for each bird species, as does the number of eggs laid, necessary incubation time and the condition of the chicks at hatching.
The term water bird, or aquatic bird is used to refer to birds that live on or around water. Some water birds are Seabirds such as penguins, pelicans and gulls. Others are Anseriformes which include ducks, geese and swans. Some birds are wading birds, who are commonly found along shorelines and mudflats and they wade into water in order to forage for food and here we have the storks, herons and egrets. Predatory birds will hunt and feed on rodents and other small animals and they usually have strong curved talons for catching or killing prey. Flightless birds are called running birds and the ostrich, emu and roadrunner are in this category. Most birds are perching birds and they are sometimes called songbirds. These birds are the most familiar to most people, they are the typical bird that everyone sees and they include species such as warblers, thrushes, sparrows, finches, jays, larks and wrens.
Birds can be deceived by windows and many have been known to crash into them. Often, stunned birds with no physical injuries like broken wings can recover quickly from a window collision without any human assistance other than a watchful eye to make sure no potential predators (most likely cats) swoop in for a quick lunch. Although it is widely understood that wind turbines do cause bird mortalities due to turbine collisions. Collision rates and impacts on bird populations are tentative and wide ranging since data is not subject to scientific review.