BIRDS
Birds are feathered, warm-blood animals with backbones. They have two feet and two wings. Their feathers are modified for flight and they have an active metabolism. Many animals such as bats, butterflies, and other insects have wings and fly. What distinguishes birds from other flying creatures are feathers. Birds are the only animals with feathers. Even bird that don't fly such as ostriches and kiwis have wings and feathers. [Source: David Attenborough, The Life of Birds, Princeton University Press, 1998]
Bird have the highest body temperatures of animals. Many species have a temperature over 43̊C (110̊F). This means they have very rapid metabolism and have to consume a lot of food relative to their body weight to keep themselves going. Modern birds have traits related to hot metabolism, and to flight: 1) horny beak, no teeth; 2) large muscular stomach; 3) feathers; 4) large yolked, hard-shelled eggs; and 5) strong skeleton. The parent bird provides extensive care of the young until it is grown, or gets some other bird to look after the young. [Source: Animal Diversity Web (ADW)
Americans spent $31 billion on birdwatching in 2007, which is $6 billion more than they spent on books. Bird provide humans with a number of symbols: wisdom (owls). peace (doves), stupidity (dodos), war (eagles and hawks), tackiness (pink flamingos), freedom (birds in flight), deprived of freedom (caged bird). Among the terms used to describes of birds are an exaltation of larks and a murder of crows.
Research has shown that 30 percent of the flying done by birds is done for fun.
RELATED ARTICLES:
BIRD FLIGHT: FEATHERS, WINGS, AERODYNAMICS factsanddetails.com ;
BIRD BEHAVIOR, SONGS, SOUNDS, FLOCKING AND MIGRATING factsanddetails.com
Websites and Resources on Birds: ; Essays on Various Topics Related to Birds stanford.edu/group/stanfordbird ; Avibase avibase.bsc-eoc.org ; Avian Web avianweb.com/birdspecies ; Bird.com birds.com ; Birdlife International birdlife.org ; National Audubon Society birds.audubon.org ; Cornell Lab of Ornithology birds.cornell.edu ; Ornithology ornithology.com ; Websites and Resources on Animals: Animal Diversity Web animaldiversity.org ; BBC Earth bbcearth.com; A-Z-Animals.com a-z-animals.com; Live Science Animals livescience.com; Animal Info animalinfo.org ; World Wildlife Fund (WWF) worldwildlife.org the world’s largest independent conservation body; National Geographic National Geographic ; Endangered Animals (IUCN Red List of Threatened Species) iucnredlist.org
Bird Taxonomy and Species
There are about 30 orders of birds, about 180 families, and about 2,000 genera with 11,000 species. One order, the Passeriformes (which includes songbirds) contains about half of the species. A total of 129 species of bird have become extinct, including the passenger pigeon and the dodo. Birds are a monophyletic lineage, evolved once from a common ancestor, and all birds are related through that common origin. There are a few kinds of birds that don't fly, but their ancestors did, and these birds have secondarily lost the ability to fly.
According to the New York Times: Birds are considered the most well-cataloged class of organisms — far more is known about them than about insects, for instance. But still, 160 new species were discovered between 1990 and 2020. Joel Cracraft, curator of the department of ornithology at the American Museum of Natural History in New York City, said the definition of a bird species is somewhat fluid because 60 percent of bird species interbreed. “This is the internecine battle over species concepts, which goes on and on,” Dr. Cracraft said. The criteria he and colleagues established in a 2007 study, essentially comes down to: “If it’s distinguishable, it’s a new species.” [Source: Karen Weintraub, New York Times, January 9, 2020]
History and Study of Birds
Birds evolved from reptiles about 140 million years ago. Transitional fossils are ones that show evolution from one group to another. Once called missing links they have ancestral features of the older species as well as novel traits of the descendant. Archaeopteryx is regarded as a transition fossil between dinosaurs and birds. Dated to 150 million years ago and discovered in Germany in 1861, this first bird retains traits such as a long bony tail and a full set of teeth. But is has birdlike wings and feathers. Its fingers are less fused and more open than in modern birds. Nine fossils of this magpie-size creatures have been found, including one with a velociraptor’s deadly claw. [Source: Newsweek, July 2, 2007]
Humboldt University Museum of Natural History in Berlin contains perhaps the world's most famous fossil, a sandstone imprint of the “Archaeopteryx” — the legendary 80-million-year-old “missing link — between dinosaurs and birds. Unfortunately the fossil is considered so valuable it is kept under lock and key in special vault and not displayed. A Japanese professor who was allowed to see it was so awestruck when he laid his eyes on it he fell down on his knees and nearly fainted.
Çagan Sekercioglu is a Turkish-born ornithologist and professor at the University of Utah. When asked by National Geographic if there are any physical hazards to his work, he said: “A whole range, from the mundane to the exotic. While surveying birds I’ve been charged by a grizzly bear in Alaska and an elephant in Tanzania. I’ve tangled with a poisonous puff adder in Uganda. I’ve been caught between the military and terrorists, mistaken for a spy, held at gunpoint, carjacked in Ethiopia, and attacked by a machete-wielding mob in Costa Rica. Honestly, I’m often more afraid of people and traffic than I am of wildlife. [Source: Pat Walters, National Geographic, November 2013]
Dinosaur-Era Birds and Bird-like Dinosaurs from China
"Confuciusornis sanctus", a 150-million-year-old bird found in Liaoning, is the earliest bird yet found. It had a toothless beak, feathered wings, claws that could be used to climb trees, feathers like modern birds and long tail feathers reminiscent of those found in some tropical birds and birds of paradise. Named in honor of the Chinese sage, "Confuciusonris" lived during the Jurassic period. Most early birds date back to the later Cretaceous period and scientist have speculated that they evolved from Jurassic age dinosaurs. For a long time the Archeareopteryx was the earliest known bird. Found in Germany, it lived 149 million years ago and is thought to have led to a dead end.
Sinosauropteryx" ("Chinese dragon-bird”) is a small bipedal birdlike dinosaur found at Liaoning in 1996. It was the first nonbird whose fossil included featherlike structures. It has been offered as proof that birds evolved from dinosaurs.
Among the other species with birdlike features found in Liaoning are "Protarchaeopteryx" and "Caudiperyx zoui", dinosaurs that looked like little velocirpators with featherlike filaments on their bodies, tails and arms. These creatures lived 120 million to 140 million years ago. Scientist have coined the name Dromeosaur to describe a group ro two legged predators that share a common ancestor with birds. Dromeosaurs in turn belong to a subgroup of dinosaurs called theropods that share about 1,000 anatomical features with birds, including wishbones, swiveling wrists and three forward-pointing toes.
Fossils of a primitive bird called "Protopteryx" contains three different kinds of feathers: downy feathers on the head and body, true flight feathers and scalelike central tail feathers.
In June 2007, a birdlike dinosaur the size of tyrannosaur was found in the Erhain basin in Inner Mongolia. The five-meter-high, 1,400-kilogram dinosaur, called "Gigantoraptor erlainensis", had a beak, slender legs and likely had feathers. Its discovery indicates tar the evolution of dinosaurs and birds was much more complicated than previously thought. Xu Xing, a scientists at the Chinese Academy of Sciences in Beijing who led the team that made the discovery, told AP, “This is like having a mouse that is the size of a horse or a cow. It is very important information for us in our efforts to trace the evolution process of dinosaurs to birds. Its more complicated than we imagined.”
See Separate Article: FEATHERED BIRD-LIKE DINOSAURS, EARLY BIRDS AND PTEROSAURS FROM CHINA factsanddetails.com
Bird Characteristics
All birds have beaks instead of jaws and teeth. Their wings correspond with the front legs of other animals, and their legs correspond with the rear legs of other animals. All birds lay eggs. Most make nests, which are used to care for eggs and young birds. Birds are endotherms (warm-blooded animals) like mammals not ectotherms (cold-blooded animals) like reptiles even though they are sometimes placed in same animal order as reptiles, Reptilia.
Birds have very large, strong hearts. They need them to pump large amounts of blood necessary to provide oxygen to the muscles needed for flight. Birds also have sophisticated breathing systems. Unlike mammals, which have lungs that are like inflating and deflating bags, bird lungs are comprised of a series a tubes, which draws in more oxygen.
Bird don't perspire. They have air sacs connected to their lungs that help keep the bird cool and lightens the bird. Bird also never get out breath. Their wing strokes expel air from the lungs. The faster a bird flaps its wings, the more carbon dioxide it need to expel, and the faster the air is expelled.
Most birds have three forward-facing toes and one backward-facing toe. Birds that spend most of their time on the ground tend to have long legs that they can use for running. Those that spend their time in trees have short, strong legs that ideal for perching, climbing and hopping. Those that spend a lot of time in the water have webbed feet that serve as paddles when the bird swims.
Eggs and Chicks
All birds lay eggs, a trait they inherited from reptiles. Bird are only vertebrates that exclusively lay eggs. Some species of other egg laying creatures such as reptiles and fish give birth to live young. Mammals give birth to live young partly because many mammal young need to move around to some degree to escape from predators soon after they are born.
Caring for eggs and young birds in many ways is more demanding and requires more attention than caring for live young. One of the main reasons that birds lay eggs is that carrying young around inside their body adversely affects the ability of the mother to fly. If the young can be removed from the body as quickly as possible in the form of an egg then the mother can continue flying even if she has had half a dozen young.
As an ovum passes down the duct leading from the female's ovary it is joined by a bag of yolk that provides nearly all the food needs for the developing embryo and chick. The ovum is then fertilized by a single sperm. Water and other nutrients are provided by the albumen which is wrapped around the yoke. The ovum yolk and albumen mass then moves down passage called the ovidcye until they reach a section with a lime-secreting gland, which produces the shell. Further down are other glands which may decorate the shells with specks of pigment. The eggs is then pushed further and expelled.
Once embryos begin developing in their eggs they need to be kept warm. Otherwise they will die. Most often their mothers, and sometimes their fathers, keep them warm by sitting on them in the nest. Many birds have brood patches — areas denuded of feathers and rich in blood vessels used to warm the eggs. The incubation period can be anywhere from 10 to 80 days. usually small birds ahem shorter incubation period.
Most chicks have an egg tooth — a tiny white spike usually on the upper mandible — and a special muscle on the back of their necks — which give strength to pull their heads backward an deliver pecks that are for strong enough to break the shell. Bird eggs contain copious amounts of yoke so that the hatchlings emerge relatively large and strong and can quickly reach a size in which they are less vulnerable attacks from predators. An egg shell is not thicker than it is because the chick ultimately has to break out of it and the shell must be porous so that oxygen can reach the embryo.
Some birds emerge helpless and need considerable attention for some weeks after they are born. Others like ducklings emerge relatively ready to take care of themselves. Baby bird usually require between one half to their full body weight in food every day. Many parent birds regurgitate food to their young.
Bird Senses
Many birds, have keen eyesight. Most fly during the day and rely on eyesight to catch prey in mid air, avoid any obstacles and assess distance so they can land properly. Some species can see well in ultraviolet light and are better at distinguishing detail than humans.
The eyesight of predators is especially keen and is regarded as the most efficient and sensitive of all animals. A sparrow hawk can spot a grasshopper from a hundred meters up and swoop down, keeping its eye on the grasshopper the whole time. Some hawks have eyes that are larger than those of humans even though they are considerably smaller than humans.
Many birds, including starlings and parakeets, see plumage that reflects color only in the ultraviolet part of the spectrum, which humans can’t see. A starling that may look black to us but may look psychedelic to other starlings. Birds that colorful to us may look completely different to other birds who see ultraviolet light.
Bird have three eyelids. One is transparent and moves from side to side instead of up and down and helps protect the eyes from dust.
With the exception of vultures and other carrion eaters, most birds don't have a very developed sense of smell. Research indicates that some species anyway use their sense of smell to distinguish between members of their own kind. A study by U.S. and French researchers Francesco Bonadonna and Gabrielle Nevitt published in Nature found that some seabirds carry the scent of their partners on their nose and were able to locate their partners in colonies with thousands of birds after being separated for weeks.
Birds that lose their hearing often regain it in about a month.
Bird Colors
Many birds get their colors from melamine, the same substance that creates different skin colors and hair colors in humans. Some of the brighter hues are the product of diet. Many birds eat foods rich in carotenoids, the antioxidant chemicals that make fruits and vegetables orange, red and yellow. The color is often limited to a few choice locations such as the shoulder spots of the red-winged blackbird or the rouged cheek pads of the zebra finch. Some birds like cardinals are very efficient at extracting carotenoids from their food, and thus are covered in color and can maintain it even when carotenoids are lacking in their diets. Other birds such as house finches change color from yellow to red depending at their carotenoid intake.
Other birds get a metallic sheen and dazzling colors not from pigments but from optical features that reflect specific wavelengths of color. These structural colors, which don’t fade and are more brilliant than those produced by pigments, are of great interest to companies that make paint, cosmetics and holograms for credit cards.
Some birds owe their colors to the structural architecture of their feathers and skin which break up sunlight into colors. Bluebirds get their blue from light waves reflected by air bubbles trapped in their feathers. The green stripe above the eyes and beak of the velvet asity is produced by light reflected from collagen in the bird’s skin. The iridescence on a hummingbird’s throat is caused by a structural effect called coherent scattering.
Many of the most brilliantly-colored birds come from the tropics. Many are residents of the upper canopy of rain forests where they can display their colors to their optimum effect in the bright light. Other brightly-colored birds such as manakins and honey creepers spend most of their time in forest understories where only scattered rays of sunshine penetrates and do choreographed acrobatic mating displays in which they alternately flash and hide their colors as they move though the stippled sunshine, somewhat like dancer below a spinning disco ball.
Some of their brightest blue colors belong to birds that spend their time in the deep forest rather than in open habitats. Why does this occur when it seems like orange would be the most visible color? Research seems to show that many animals are visually sensitive to anything outside their usual habitats Since the dominant colors in a forest are green, brown, yellow and sometimes orange, blues and violets are rare background colors.
The Gouldian finch of Australia has brilliant natural plumage. According to the Times of London it “sports a gaudy patchwork of yellow, purple, green, black and blue plumage. Bird fanciers have tried to make a white one...The zebra finch illustrates how far bird breeders genetic tinkering extends. The plumage of the male zebra finch consists of a blaze of colored patches, stripes, spots and bands. Amateur bird breeders have in effect dismantled the part of the finch’s genome dealing with plumage and can now create — almost to order — birds with or without these patches. Color is almost entirely controlled by a handful of genes which can be manipulated. The longer people mess with them they more varieties that are produced. Pigeons are the record holders with more than 350 varieties breeded as of the early 2000s. [Source: The Times of London]
Beaks, Food and Bird Digestion
A beak is made of a horny sheath of keratin and weighs much less than jaw bones and teeth. "Chewing" is done in bird's gizzard, a special compartment of the stomach, which is located near a bird's center of gravity so it doesn't interfere with flying. Some birds can’t fly if they eat too much.
Beaks serve as both a mouth and hands and are used more for gathering food than eating it. Bird use them to pick up food, for defense and sometimes to build nests. Beaks are molded easily by evolution forces and over millions of years have developed to feed on particular food. See Darwin and finches.
Bird eats food rich in calories such as nuts, seeds, fruit, insect larvae and fish. They need all these calories because flying requires a lot of energy. Birds seem to care less about taste than other animals. A parrot has only 350 taste buds compared to 17,000 for a rabbit.
Food passes through the mouth into the gullet and then the crop, a thin-walled pocket that is used to store food for later digestion or regurgitation for feeding young. The crop is especially well pronounced in grain-eating birds. The gizzard is the avian equivalent of a stomach. It is connected to the intestines. Bird have no urinary tract. Nitrogenous wastes is excreted in the form of urea through an opening called the cloaca.
Many birds eat seeds and little else. Seeds are rich in food and nutrients but are surrounded by thick shells. To get around this many birds have strong muscles in their gizzards that break up the shells and swallow dirt and grit which function as an abrasive. Birds use a gizzard rather than teeth because gizzards are lighter.
Adaptions By Birds to Different Environments
Different birds have adapted themselves to different habitats and in the process developed into different species. Birds living in savannahs, grasslands and deserts such as ostrich and emu have larger sizes. Their wings degenerate and they lost their ability to fly. But their feet are very strong and they can run very quickly. Therefore, they become cursorial (running) birds. [Source: Center of Chinese Academy of Sciences, kepu.net.cn]
Wild ducks, wild geese, pelicans, cormorants, gulls, albatrosses, frigate birds and sea swallows like to live on rivers, lakes and seawaters. Some of them are good at swimming and some are good at diving; therefore, they become birds of swimming.
Egrets, water rails, cranes and storks have long necks, legs and bills and like to walk and search food in shallow waters and swampland. Therefore, they are called wading birds. Other birds like jungle fowl (chickens) and peafowl (peacocks) walk on the ground and are good at walking instead of flying. Thus, they are called terrestrial birds.
Observing finches on the Galapagos island gave Charles Darwin some of his greatest insighst into evolution. The 13 different species of finches he found there each have a different kind of beak to deal with extracting food in a particular environment. "Seeing the gradation and diversity of structure in one small, small intimately related group of birds, one might really fancy that from an original paucity of birds in this archipelago, once species had been taken and modified for different ends,” he wrote.
Bird Conservation and Global Warming
Scientist say progress has been helping some of the most endangered bird species. A total of 31 birds including the California condor and Mauritius parakeet are said to have probably become extinct if it wasn’t for human intervention. Among the measures tat have helped birds are preserving their habitats, breeding and moving birds and controlling cats. Britain-based Birdlife International launched an ambitious plan in 2007 to raise millions of dollars to help protect 189 endangered species of bird on the brink of extinction. The efforts is aimed at protecting habitats, raising awareness and reducing invasive species that often eat bird eggs and compete for food.
According to research by a team lead by Victor Devictor, a researcher at the French National Museum of Natural History found that the habitats of wild bird species are shifting in response to global warming but not fast enough to stay ahead do rising temperatures. The study found that the geographic range of 105 bird species in France — accounted for 99.5 percent of the country’s wild birds — had shifted an average of 91 kilometers north between 1989 and 2006. The evidence was based on observations of birds by ornithologists and amateur birders at different times in 1,500 well-defined plots starting in 1989.
There have a number of observations of individual species shifting northward. What was particularly startling about the French study was that virtually all the bird species studied moved northward, “The response is faster than we thought but it is still not fast enough to keep up with climate change.”
Perhaps the worst consequence of global change for birds is that timing of their birds and their insect prey is getting out of sync. “The flora and fauna around us are shifting over time due to climate change,” Devictor told AFP. The result is desynchronisation. If birds and the insects upon which they depends do not react in the same way, we are headed for an upheaval in the interaction between species.”
A study by Stephen Willis of Durham University in Britain found that global warming is causing migrating birds to migrate further as their breeding grounds shift northward. His team that found that some types of warblers have to add 400 kilometers onto a already exhausting trips up to 6,000 kilometers to and from Africa. “For some bird the extra distance might make the difference between being able it make it or not. The study was published April 2009 in the Journal of Biogeography.
See Separate Article: CONSEQUENCES OF CLIMATE CHANGE — ON ANIMALS, PLANTS, FARMS AND OCEAN CURRENTS factsanddetails.com
Endangered Birds and the Illegal Bird Trade
According to the official Red List by the World Conservation Union one in eight bird species is threatened. By some estimates at least on in ten bird species is likely to die out by the end of the 21st century, with another 15 percent hoovering on the brink of extinction. There are already some species that are raised in captivity but extinct in the wild..
In the last 500 years 135 species of bird have become extinct in the last 500 years, including, 8 in the 16th century, 11 in the 17th century, 26 in the 18th century, 49 in the 19th century and 43 in the 20th century.
Species have been lost due to poaching, habitat loss and overdevelopment. In the last three decades 21 species have been lost, including the Spixs macaw and the Hawaiian honeycreeper. Among the species that been saved through conservation efforts are the Bengal Florican in Cambodia, the Belding’s Yellowthroat in Mexico and the Restinga Antwren from Brazil.
Pet store birds generally have not had a very pleasant past. Some have been caught in the wild and subject to cramped cages and uncomfortable transportation. Many birds have been bred under stressful conditions.
In 2005, 1.5 million exotic birds as pets, 90 percent of the world’s total, were imported by Europe. In 2006, a ban that was put in place in Europe to halt the spread of bird flu also shut down the exotic bird trade, which was issued for all wild-caught birds.
Image Sources: Wikimedia Commons
Text Sources: Mostly National Geographic articles. Also David Attenborough books, Live Science, New York Times, Washington Post, Los Angeles Times, Smithsonian magazine, Natural History magazine, Discover magazine, Times of London, The New Yorker, Time, Newsweek, Reuters, AP, AFP, Lonely Planet Guides, Compton’s Encyclopedia and various books and other publications.
Last updated February 2025