Childrens Illustrated Encyclopedia

74

Mandibles (beak)

Crop

Heart

Gullet

Pygostyle

(tail bone)

Skeleton of a pigeon

The biggesT and

Birds 74-

The tiny bee hummingbird

is one of the world’s

smallest birds. it measures

about 2 in (5 cm) from

beak to tail, and is so light

that 17 bee hummingbirds

would weigh only 1 oz

(28 g). The ostrich, which

is more than 8 ft (2.5 m)

tall, is the world’s largest

bird, but it cannot fly at all.

Birds

in The enTire animal world, birds are the only living creatures

with feathers. They are warm-blooded, like mammals. There are about

10,200 different kinds of birds, living in all parts of the world. They

include exotic, colorful birds such as parrots, garden birds such as

robins and thrushes, water birds such as ducks, sea birds such

as puffins and penguins, and many more. most birds are well

adapted for flying and have large, powerful chest muscles to

allow them flap their wings. many of their bones are light,

with tiny honeycombed holes to keep them lightweight,

which assists them during flight. Feathers are light, too.

They protect the bird’s body and keep it warm. wing

feathers fit together to form a smooth, airtight surface

for gliding. Tail feathers provide balance and help the

bird steer in midair. a few birds, however, cannot fly.

Flightless or nearly flightless birds include ostriches,

penguins, kiwis, and the rare kakapo, a kind of parrot

from new Zealand. birds do not have teeth, which

would be too heavy; instead they have a strong, light

bill, or beak. most birds, particularly eagles

and other birds of prey, have good

eyesight and hearing. some

species use their sense

of smell to navigate,

forage, or even

distinguish individuals.

bird bones

most of the bones in a bird’s

skeleton are hollow, to save

body weight. wings are

controlled by powerful

muscles attached to the keel,

which is a ridge along the

edge of the breast-bone.

inside a bird

a bird’s digestive system

includes a crop for storage and two stomachs.

any food eaten by the bird is held in the crop.

The first stomach, the proventriculus, starts to

digest food. it is then ground into a pulp in the

second stomach, the gizzard.

Internal system of a starling

Long tail feathers

act as a rudder, to

help with steering

during flight.

This ostrich head

looks huge in

comparison to

a tiny bee

hummingbird.

A bee hummingbird

is so small that it

could fit in the palm

of your hand.

Beak (bill)

Lungs

Kidney

Liver

Intestine

Gizzard

Ribs

Keeled sternum

(breast bone)

Tibia (shin bone)

Femur (thigh bone)

Pelvis

(hip bone)

Skull

Radius and ulna

(forearm bones)

Outer

feathers

produce

lift for

flight.

Short,

strong beak

for cracking

open

seeds.

Tarsus (ankle

bone)

Male chaffinch

in flight

Humerus (upper arm bone)

Plumage

a bird’s feathers are

called its plumage.

some birds, such as the

wren and the sparrow,

have brown plumage for

camouflage. other birds

have plumage with dazzling colors and patterns. it is

usually the males that have bright plumage, to help them

attract a mate during the breeding season. The distinctive

coloring also helps the members of a flock stay together.

Cloaca

Brightly

colored

plumage attracts

a female in the

breeding season.

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