Birds are one of the six basic groups of animals. Birds, best known for their ability to fly, are unmatched in their command of the skies. Albatrosses glide long distances over the open sea, hummingbirds hover motionless in mid-air, and eagles swoop down to capture prey with pinpoint accuracy. But not all birds are aerobatic experts. Some species such as kiwis and penguins, lost their ability to fly long ago in favor of lifestyles suited more for land or water.
FACT: Birds are divided into 30 groups.
Although there are several different ways experts classify birds into subgroups, on this website we recognize that there are 30 groups of birds.
FACT: There are 9,865 species of birds alive today, according to the IUCN.
Of the 9,865 bird species, 1,227 species are considered threatened with extinction, 838 species are near threatened, 7,735 species are considered to be of least concern, and 65 species lack the data to determine their status. 133 species of birds are known to have gone extinct since 1500. There are also four species of birds that are classified as extinct in the wild. The last living members of those species survive only in captivity.
FACT: The earliest known bird, Archaeopteryx lithographica, lived about 150 million years ago during the Jurassic Period.
Archaeopteryx possessed a blend of reptilian and avian characteristics. It had feathers and wings but instead of a bill it had a reptilian snout. Archaeopteryx did not have a keeled breastbone, a key feature for flight, so scientists are uncertain whether it was capable of true flight or if it merely glided. A total of ten Archaeopteryx fossil specimens have been unearthed over the years. All of these fossils were recovered from the limestone deposits in quaries near Solnhofen, Germany. The first Archaeopteryx skeleton, now known as the "London Specimen", was discovered in 1861.
FACT: Evolutionary biologists remain uncertain as to the origin of birds.
The fossil record for early birds lacks suffcient detail for evolutionary biologists to determine with much certainty which group of reptiles gave rise to birds. Research currently supports the view that birds evolved from a group of dinosaurs known as theropods during the Mesozoic Era. Modern birds share many characteristics with theropods. Both have hollow bones, a pelvis bone that points backward, a wishbone, and a three-toed foot.
FACT: Feathers are unique to birds.
Feathers are a defining characteristic of the group, meaning simply that if an animal has feathers, then it is a bird. Feathers serve many functions in birds but most notable is the critical role feathers play in enabling birds to fly. In addition to helping to enable flight, feathers also provide protection from the elements. Feathers provide birds with waterproofing and insulation and even block harmful UV rays from reaching birds' skin.
FACT: Birds are not the only animals that are capable of flight.
Flight is not a characteristic restricted to birds. Bats, which are mammals, fly with great agility and insects, which are arthropods, were fluttering through the air several million years before birds took to the wing.
FACT: All birds reproduce by laying eggs.
Eggs vary in size and color depending on species. Although there is a wide range of egg colors, only two pigments contribute to the color of the shell. The first pigment is derived from hemoglobin and the second from bile. Most species lay their eggs in a nest. Nests may vary in size, shape, and construction material, but the most common nest shape is cup-shaped.
FACT: Many birds undertake seasonal migrations between their breeding and wintering grounds.
Many species of birds migrate to high latitudes to breed during the spring and summer. Then during the fall and winter months they migrate to regions of lower latitude. Many species follow similar routes each year when migrating. These routes are referred to as migratory flyways.
FACT: Birds do not have teeth.
Instead they have bills that are made of the protein keratin. Bird bills come in a variety of shapes and sizes and are adapted to the particular diet of each species. Herons, for example, have a sharp, pointed bill that enable them to capture fish. Finches on the other hand have a short, conical bill that is well-suited for cracking open seeds (Burnie and Wilson 2001, 261).
FACT: The largest of all birds is the ostrich.
Ostriches are flightless birds that have a large body, small head, long legs, and a long neck. Although they cannot fly, they are remarkable runners, able to run at speeds of up to 45 mph for half an hour. Adult ostriches weigh between 220 and 350 pounds and measure between 7 and 9 1/4 feet in height.