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ArchAeopteryx
One of the first birds known
to have existed is called
Archaeopteryx. Fossil remains
date back 150 million years.
Archaeopteryx could glide
and fly through the air.animal
BIRDS, BATS, AND INSECTS are the only animals that truly fly. Other animals,
such as flying squirrels, flying fish, and flying lizards, swoop or glide, but cannot
climb upward into the air under their own power. Life in the air has several
advantages for flying animals—some birds, such as hawks, can hunt their prey in
midair; other birds can quickly escape from their predators. Birds are also able
to migrate very long distances to find more suitable feeding and breeding areas
in a cold season—the Arctic tern, for example, migrates about 11,000 miles
(18,000 km) from the North Pole to the South Pole every year. Another bird,
the swift, spends much of its life in the air, landing only to nest. A swift eats and
drinks on the move for nine months of the year. Birds, bats, and insects are also
able to find food on land quickly and efficiently—a hummingbird hovers to
gather nectar, a fruit bat flies into a tree to feed on fruit, and a dragonfly swoops
over a pond to catch small flies. All flying animals from
bees to buzzards need plenty of food to provide
them with the energy to take to the air.
Animals first began to fly about 300 million
years ago, when Earth’s prehistoric coal
swamps were becoming overcrowded
with all kinds of creatures.
Through evolution,
special features began to
develop, such as a flap
of skin on the body for
gliding. In order to fly,
an animal needs a lightweight body
and strong muscles with which to flap
its wings. Birds have hollow bones
to save weight when they are in
flight, so that a huge bird such
as the golden eagle
weighs less than
9 lb (4 kg).FliGHT
Powerful wing-flapping
pectoral muscles are in
the bat’s chest.Wing of a kestrelBatMain bones
in the wingSkin stretches between
the forearm and
finger bones.Elastic fibers allow the
wings to shrink so
the bat can fold
them neatly.Covert feathers are
at the front of the
wing. They are
small and packed
closely together, to
give a smooth edge.Primary flight
feathers help
reduce turbulence.Feathers near the wing
root shape the wing
smoothly into the body.Flight feathers are light
and stiff, with strong shafts
and large, smooth vanes.SOOTy TERN
The sooty tern lives
on the move for up
to 10 years. It returns to
the ground only to breed.WINgS
The wings of a
flying animal are
light so that they
can be flapped easily.
They are broad and
flat, to push the air
downward and give lift.
Wings must also be flexible for
control in the air. An insect’s
wings are made of a thin
membrane stiffened by tubelike veins.
A bird’s wings have bones and muscles at
the front; feathers form the rest of the
surface. A bat’s wings consist of a thin layer of
muscles and tough fibers sandwiched between
two layers of skin that are supported by bones.US_210_Flight_Animal_1.indd 210 21/01/16 4:58 pm