Chapter 5 Notes: Birds
Bird Characteristics that are important for flight.
Characteristics
Feathers
Lighter Skeleton
Air Sac
Heart
Large eyes
Wings
Rigid Skeleton
Flight Muscle
Description
Feathers help the bird fly. A series of hooks link the barbs of
a contour feather, keeping the feather smooth.
Bone is a heavy material, but birds have much lighter
skeletons than those of other vertebrates because their bones
are almost hollow. The bones are still very strong they have
thin cross-supports that provide strength, much like the trusses
of a bridge.
The air sac is attached to their lungs. This increases the
amount of oxygen that a bird can take in and allow air to glow
constantly in one direction through their lungs.
The heart of a bird beats rapidly. This ensures that flight
muscles get as much oxygen as the blood can carry. In small
birds, the heart beats almost 1,000 times a minute! Your heart
beats about 70 times a minute.
Most birds have large eyes and excellent eyesight. This
allows them to see objects and food from a distance. Some
birds, like hawks and eagles, can see eight times better than
humans.
The shape of a bird’s wing is related to the kind of flying it
does. Short, rounded wings allow rapid maneuvers, like the
movements of a fighter plane. Long narrow wings are best for
soaring, like the movement of a glider.
Bird skeletons are compact and strong. Some of the vertebrae,
ribs, and hip bones are fused together. This makes the
skeleton of birds more rigid than that of other vertebrates. The
rigid skeleton lets the bird move its wings powerfully and
efficiently.
Birds that fly have powerful flight muscles attached to a
breastbone called a “keel.” These muscles move the wings.
3 Types of feathers
1. Contour feathers – a large feather that gives shape to a bird’s body
2. Flight Feathers – these are the long contour feathers that extend
beyond the body on the wings and tail. They help the bird to balance
and steer during flight.
3. Down Feathers – short fluffy feathers that are specialized to trap heat
and keep the bird warm. These feathers are found right next to the
bird’s skin, at the base of the contour feathers.
Birds have a two-loop circulatory system and a four-chambered heart. The
advantage of a four-chambered heart is that oxygen-rich blood does not mix
with oxygen-poor blood.
Category
Water Fowl
Flightless
Perching
Birds of Prey
Four major Classifications of birds
Description
Examples
Usually have webbed feet for
Cranes, ducks, geese,
swimming, but they are also
swans, pelicans, loons,
strong flyers.
and many others.
These birds do not have a large
Ostriches, kiwis, emus,
keel for flight. Though they
penguins (these birds
cannot fly, many flightless birds
have a large keel but their
are fast runners
wings have been
modified into flippers)
These birds have special
Songbirds, like robins,
adaptations for perching on a
wrens, warblers, and
branch, its feet automatically
sparrows.
close around the branch.
Birds of prey are meat eaters.
Eagles, hawks, falcons,
They may eat mammals, fish,
owls, ospreys and others.
reptiles, birds, or other animals.
The sharp claws on their feet and
their sharp, curved beaks help
these birds catch and eat their
prey. They also have very good
vision. Most hunt during the day.
Precocial – These birds hatch from an egg ready to run around and eat bugs.
They are covered with downy feathers and follow their parents as soon as
they can stand up. Examples of these birds are chickens, ducks, shorebirds.
Altricial – These chicks are born weak, naked and helpless. Their eyes are
closed when they are born. These birds cannot fly or walk. Their parents
must keep them warm and feed them for several weeks.
The difference in pressure above and below the wings as a bird moves
through the air produces an upward force that causes the bird to rise. That
upward force is called lift.