Birds, members of the class Aves, include more than 10,400 living species. Their feathers distinguish them from all other classes of animal; no other animals on earth have them. If you see an animal with feathers, it’s undoubtedly a bird. Like mammals, birds are warm-blooded vertebrates with four-chambered hearts. However, they are more closely related to reptiles and are believed to have evolved from dinosaurs. Their forelimbs have been modified into wings over many millions of years of evolution, they lay hard-shelled eggs and they have exceptional vision – the most acute of their senses. Most birds are diurnal, meaning they sleep at night. Most can fly, but flightless species exist.

Five Top Bird Characteristics

Certain identifying characteristics distinguish birds from other classes of animals. Five especially important distinguishing characteristics of birds include:


All birds have feathers, which are actually highly evolved scales. In fact, birds have scales on their feet – the clearest reminder of their close relation to reptiles. As noted above, feathers are not found on any other class of animal. Like nails and hair on humans, feathers are made out of keratin. They serve a number of purposes, from providing warmth to assisting in the ability to fly. Most birds shed, or molt, their feathers one or two times per year. Contour feathers help birds to fly effectively and create a streamlined body shape. Soft, fluffy feathers provide warmth. Flight feathers, found on the wings and tail, provide loft. Male birds also often use their feathers to attract mates.


Wings are a primary characteristic of birds, but they are found on other types of animals too. For example, bats are flying mammals with wings, and many types of insects have wings. Strong muscles in the chest help to propel wings, allowing for flight. Bird bodies are curved specifically to give lift to the wings. Different wing shapes provide different advantages, depending on species. For example, wings that have sharp, narrow tips allow for greater speed. Wings that are longer than they are wide make it easier for birds to soar for extended periods of time. Elliptical, evenly shaped wings, which are most notably found on songbirds, allow for small, quick movement. Birds that are capable of swimming, like penguins and puffins, have wings that are shaped like flippers.


All bird species have beaks, or bills – bony concentrations that are surrounded by layers of keratin. The shape of a bird’s beak provides strong clues about its dietary habits. Although some birds have tumia, sharp ridges along the edges of their beaks, none possess true teeth. Therefore, the beak plays a crucial role in feeding. Birds that primarily subsist off of seeds, for example, tend to have strong, cone-shaped beaks. Ducks, geese and other types of waterfowl have broad, flat beaks that are designed to help them strain food from water. Meat-eating birds like owls and hawks have sharp, hooked beaks that they use to grind, tear and rip their prey to shreds.


Egg laying is another characteristic that is common to all birds, or members of the Aves class. However, it is not unique to this class of animals, as reptiles, fish, amphibians and insects also all lay eggs. Birds’ eggs have hard shells that are mostly made out of calcium; a layer of hardened mucus helps to keep them intact. Within an egg, the embryo gets its nutrition from the yolk and the egg white, which is known as albumin. The vast majority of bird species build nests for their eggs and proceed to care for the hatchlings until they are capable of fending for themselves. In most species, both males and females play important roles in caring for the young.

Nearly all birds incubate their eggs. Exceptions include megapodes, or mound builders, which rely on external heat sources like decaying vegetation, and brood parasites. The latter, including cuckoos and cowbirds, prefer to lay their eggs in other birds’ nests. Some birds, like murres and certain penguin species, don’t use nests at all, choosing instead to rest eggs on the tops of their feet during incubation. Incubation periods range from 11 to 80 days depending on species.

A set of eggs that is laid at one time is called a clutch. Anywhere from one to 20 eggs or so may be found in a single clutch. Some birds engage in determinate laying, meaning that they lay the same number of eggs per clutch every time. Most birds engage in indeterminate laying, meaning that the number per clutch varies.


Flightless species of birds have heavy bones that are filled with marrow. Birds that are capable of flight – in other words, most birds – have lightweight skeletons made up of hollow bones. Their skeletons have many fused bones, including collarbones, which help them to brace their wings effectively during flight. Birds have large breastbones, or sternums, that provide sturdy points of attachment for muscles of the wings.

Notable Types of Birds

Today, there are more than 10,400 extant bird species in the world. Across North America and South America, there are more than 4,400 species of the Aves class. Approximately 2,700 different species are found in Asia, and another 2,300 or so are found in Africa. More than 500 species are found in Europe west of the Ural Mountains, and more than 700 species are found in Russia. Costa Rica has one of the highest concentrations of bird species – roughly 800.

Some of the most notable types of birds include:

  • Birds of Prey – This group is made up of more than 300 species of birds, including eagles, hawks, ospreys, falcons and vultures.
  • Cranes – This group, which includes coots and rails, boasts more than 200 species.
  • Game Birds – Perhaps the best-known type of bird, game birds include chickens, turkeys, quails and megapodes. There are approximately 250 species of game birds in the world.
  • Herons and Storks – More than 100 species are found in this group, which includes egrets, spoonbills and ibises.
  • Hummingbirds and Swifts – The smallest category of birds, this group includes more than 400 different species.
  • Ostriches – The ostrich, the most famous flightless bird, is also the only species in its genus. It also holds the distinction of being among the largest birds.
  • Owls – Another important type of bird is the owl. There are more than 200 species of owls across the world.
  • Parrots and Cockatoos – This colorful group, which includes macaws, cockatiels and budgerigars, consists of more than 350 species. They are popularly kept as pets.
  • Penguins – There are roughly 20 species of this flightless bird in the world.
  • Perching Birds – Also known as passerines, this group includes more than 5,000 species, making it the largest and most diverse. Common types of perching birds include crows, swallows, jays, finches, sparrows, wrens, starlings and larks.
  • Pigeons and Doves – This group includes more than 300 bird species. Pigeons are famous for ferrying messages for humans, and have been used in such a way since Roman times. They were also used during World War I and II and the Korean War.
  • Shorebirds – More than 350 species are found in this group, including sandpipers, terns, oystercatchers and gulls.
  • Waterfowl – Ducks, geese, swans and many other birds belong to this group, which includes more than 150 species.
  • Woodpeckers and Toucans – Known for their distinctive beaks, this group is made up of more than 400 species.

Evolution of Birds

The evolution of birds has been a topic of much debate for many centuries. Today, the most commonly accepted theory, the theropod ancestor hypothesis, posits that birds evolved from theropod dinosaurs during the Jurassic period, which happened between 165 million and 150 million years ago. Theropod dinosaurs were two-legged dinosaurs, and the T. Rex is included among their ranks.

The earliest known bird on the fossil record, archaeopteryx, was a hybrid between a bird and a dinosaur. It had feathered wings like a bird but also had sharp teeth and a long, bony tail like a dinosaur. This and other types of early birds diversified rapidly throughout the Jurassic and Cretaceous periods. They quickly became capable fliers and exhibited extremely rapid growth rapids. However, their populations were decimated by the major extinction event that eliminated dinosaurs entirely. After that point, modern birds diversified at an explosive rate, and there are now more than 10,000 different species all across the world.

Types of Birds

A Adelie Penguin
Adelie Penguin

Eats up to 2kg of food per day!

A African Penguin
African Penguin

The only penguin species in Africa!

A Albatross

The largest wingspan of any bird in the world!

A Avocet

Has a curved, upturned beak!

A Barn Owl
Barn Owl

Found everywhere around the world!

A Barred Owl
Barred Owl

Like other owls, the barred owl swallows its prey whole.

A Bird

Not all birds are able to fly!

A Bird Of Paradise
Bird Of Paradise

There are around 50 different species!

A Blue grosbeak
Blue grosbeak

Blue grosbeak parents take off the head, legs and wings of an insect before feeding it to their baby.

A Blue Jay
Blue Jay

Blue jays rub ants on their feather to remove harmful acids

A Booby

Seabirds found across the South Pacific!

A Budgerigar

Natively found in Australia!

A Carolina Parakeet
Carolina Parakeet

The Carolina parakeet is one of the few parrots that lived as far north as the United States

A Cassowary

Can reach speeds of 30mph!

A Chickadee

Chickadees are named for the sound they make: Chick-a-dee-dee-dee-dee-dee!

A Chicken

First domesticated more than 10,000 years ago!

A Chinstrap Penguin
Chinstrap Penguin

There are 7 million breeding pairs!

A Cockatoo

Highly social, smart, and chatty bird.

A Common Buzzard
Common Buzzard

The most common raptor in the UK!

A Common Loon
Common Loon

Also known as the Great Northern Diver

A Common Raven
Common Raven

A group of ravens is called an unkindness or a conspiracy.

A Cooper’s Hawk
Cooper’s Hawk

Eyes change color as they age

A Crane

Many are critically endangered species!

A Crested Penguin
Crested Penguin

Has long yellow eyebrows!

A Dodo

Native to the island of Mauritius!

A Duck

Rows of tiny plates line their teeth!

A Eagle

Has exceptional eyesight!

A Eastern Bluebird
Eastern Bluebird

Bluebirds drop straight down on their prey from their perch, much like leopards.

A Eastern Phoebe
Eastern Phoebe

This passerine bird can sing its song without ever hearing another bird vocalize first.

A Emperor Penguin
Emperor Penguin

The world's largest species of penguin!

A Emu

The largest bird in Australia!

A Falcon

The fastest creatures on the planet!

A Ferruginous Hawk
Ferruginous Hawk

The ferruginous hawk comes in both light and dark morphs

A Flamingo

Sleeps on just one leg!

A Frigatebird

Found inhabiting tropical islands and coasts!

A Galapagos Penguin
Galapagos Penguin

Found around the Equator!

A Gentoo Penguin
Gentoo Penguin

Found throughout the sub-Antarctic!

A Golden Masked Owl
Golden Masked Owl

While flying high above this owl can hear a mouse moving in the tall grass of field!

A Golden Oriole
Golden Oriole

Migrates between Europe and Asia!

A Goose

There are 29 different species!

A Gouldian Finch
Gouldian Finch

The male Gouldian finch bobs its head and fluffs its feathers to court a female.

A Green Bee-Eater
Green Bee-Eater

Mainly eats honeybees!

A Grouse

Feathered legs and toes!

A Guinea Fowl
Guinea Fowl

Found in a vairety of African habitats!

A Harpy Eagle
Harpy Eagle

Talon's the size of a grizzly bear's claws!

A Hawaiian Crow
Hawaiian Crow

Once believed to be a family guardian spirit in Hawaii

A Heron

Inhabits wetlands around the world!

A Hoopoe

Stunning bird with a stinky way to deter predators!

A Hornbill

The bird has a massive horn on its bill!

A House Finch
House Finch

The house finch can become redder depending on what it eats

A Humboldt Penguin
Humboldt Penguin

Found on the South American coast!

A Hummingbird

Beat their wings up to 80 times per second!

A Ibis

Found in swamps, marshes and wetlands!

A Ivory-billed woodpecker
Ivory-billed woodpecker

The ivory-billed woodpecker can drill into wood with its sharp beak

A Kakapo

The heaviest species of parrot in the world!

A Keel-Billed Toucan
Keel-Billed Toucan

It's beak can reach nearly 20 cm long!

A King Penguin
King Penguin

More than 2 million breeding pairs!

A Kingfisher

Inhabits wetlands and woodlands worldwide!

A Kiwi

Only found in the forests of New Zealand!

A Kookaburra

The laughing kookaburra is one of four kookaburra species.

A Little Penguin
Little Penguin

The smallest species of penguin!

A Long-Eared Owl
Long-Eared Owl

Ear tufts make it look bigger!

A Lorikeet

The lorikeet has a long brush-like tongue with fine hairs on it

A Macaroni Penguin
Macaroni Penguin

Gather in colonies of up to 100,000 members!

A Macaw

The largest species of parrot in the world!

A Magellanic Penguin
Magellanic Penguin

Threatened by oil spills!

A Magpie

They are found across Europe, Asia and Africa!

A Mallard

With an appropriate tail wind, the mallard can travel hundreds of miles a day

A Marabou Stork
Marabou Stork

The marabou stork does not have a voice box.

A Mountain Bluebird
Mountain Bluebird

Depending on the time of the year, the mountain bird can live as far north as Alaska.

A Mourning Dove
Mourning Dove

It is almost always the male who makes the famous sad sound, which is a wooing call

A Myna Bird
Myna Bird

For a nice price, the mynah bird makes a good pet.

A Nightingale

Named more than 1,000 years ago!

A Northern Cardinal
Northern Cardinal

Males are a bright red color, also called "cardinal red"

A Ostrich

The largest bird in the world!

A Parrot

Can live for up to 100 years!

A Peacock

Most commonly found on the Indian mainland!

A Pelican

Can have a wingspan of up to 3 meters!

A Penguin

Spends 75% of it's time hunting for food!

A Peregrine Falcon
Peregrine Falcon

Fastest animal on Earth

A Pigeon

They can find their way back to their nests from up to 1300 miles away.

A Pileated Woodpecker
Pileated Woodpecker

Pairs establish territories and remain all year

A Puffin

Can remain in the water for up to 2 minutes!

A Purple Finch
Purple Finch

The intensity of the plumage can change based on what the bird eats

A Quail

Inhabits woodland and forest areas worldwide!

A Quetzal

The tail feathers of the male can be 1m long!

A Red Finch
Red Finch

Red finches can form flocks of over 100 birds.

A Red-winged blackbird
Red-winged blackbird

The male red-winged blackbird can sing to attract mates

A Robin

There are more than 45 species in Australia alone!

A Rockhopper Penguin
Rockhopper Penguin

There are 3 different species!

A Rose-breasted Grosbeak
Rose-breasted Grosbeak

Rose-breasted grosbeaks are closely related to cardinals

A Roseate Spoonbill
Roseate Spoonbill

The only Spoonbill in the western hemisphere!

A Royal Penguin
Royal Penguin

Can reach speeds of 20mph!

A Ruby-Throated Hummingbird
Ruby-Throated Hummingbird

Ruby-throated hummingbirds can beat their wings more than 50 times per second.

A Scarlet Macaw
Scarlet Macaw

Like many parrots, the scarlet macaw is capable of vocal mimicry.

A Senegal Parrot
Senegal Parrot

As a pet, the Senegal parrot is capable of "talking" to its owner

A Shoebill Stork
Shoebill Stork

Adults greet each other by clattering their bills together.

A Snowy Owl
Snowy Owl

One of the largest owl species in the world!

A Sparrow

There are 140 different species!

A Spixs Macaw
Spixs Macaw

One of earth's rarest animals!

A Swan

Populations have been affected by pollution!

A Tawny Owl
Tawny Owl

The most widespread owl in Europe!

A Thrush

The American robin is called the robin because its red breast reminded European settlers of the robin back in the old country.

A Toucan

There are more than 40 different species!

A Tree swallow
Tree swallow

The tree swallow can make more than a dozen distinct vocalizations

A Tropicbird

Nests on tropical islands and cliffs!

A Turkey

Closely related to pheasants and chickens!

A Uguisu

Their guano is used in face creams!

A Umbrellabird

Migrates up and down the mountains!

A Vulture

There are 30 different species worldwide!

A Wandering Albatross
Wandering Albatross

Featured in “The Rime of the Ancient Mariner”

A Whooping Crane
Whooping Crane

This species is named after the loud whooping sound it makes

A Woodpecker

There are 200 different species!

A Yellow-Eyed Penguin
Yellow-Eyed Penguin

The rarest species of penguin!

A Zebra Finch
Zebra Finch

The male zebra finch creates a unique song by drawing inspiration from its parent or tutor

List of Birds

Birds FAQs (Frequently Asked Questions) 

What are the four types of birds?

There are far more than only four types, or categories, of birds in the world. If “type” refers to “species,” then the figure is closer to around 10,400. Birds can be classified into different categories in a number of ways, including flightless birds versus birds that are capable of flight and birds that live mostly on land or near water.

How are birds identified?

Birdwatching, a popular pastime, involves identifying birds in the wild. Four things are looked to when identifying birds: their size and shape, their behavior, their habitat and their color patterns. By learning the basics of each of these categories, birdwatchers can identify birds in the wild more quickly – an important aspect of the sport.

Why do birds bathe?

Bathing is a vital part of feather maintenance. Water helps to loosen up dirt and other debris that has worked its way into the feathers. Once freed of dirt, the feathers are easier to preen. During preening, birds rearrange their feathers and dispense oil from the preen gland, ensuring that their feathers remain waterproof. This also traps an insulating layer of air beneath, helping to keep the bird warm.

Which birds cannot fly?

Some of the best-known examples of flightless birds include penguins, ostriches, emus, cassowaries and kiwis.