Big Birds
Eagles belong to a group of birds called raptors.
They are amazing, powerful predators with
sharp eyesight, light bodies, and soaring wings. Eagles use their dagger beaks
and sharp talons to
hunt fish,
snakes, frogs, other birds,
and small mammals.
They are some of the world’s largest birds of prey.
There are 59 different kinds of eagles on Earth and they live in every environment except
the polar regions of Antarctica. The majority of the world’s eagles soar
in the skies over Asia, Russia, and Europe. Two species live in North America
and two in South America.
The tawny eagle is a kind of soaring eagle. It hunts small animals but mostly
eats other predator’s catches or animals that have died naturally.
As long as the kill is fresh the tawny eagle will eat it.
©G.Ellis/GLOBIO.org Giants of the Treetops and Smallish Snake Hunters
The harpy eagle is a fierce hunter. They can quickly fly through the tropical
rainforest and snatch a sloth right off of a tree with its enormous talons.
©S.Holt/GLOBIO.org Scientists organize eagles into four main
groups: harpy eagles, serpent or snake eagles, booted eagles and fish or sea
eagles. Two of the largest eagles are the Philippine eagle and the harpy eagle
of tropical South America. Each can weigh more than 9
kg and have wings that spread 2
m. Using their huge talons, these giants of the treetops can kill and carry
off prey as large as monkeys.
Most eagles are large powerful hunters. However, some are just small pigeon-sized
birds that fly only short distances, eating insects and even fruit! The crested
serpent eagle is the size of a small chicken. It spends its days walking and
climbing through its African forest home, searching for snakes. Another smallish
eagle, the African vulturine fish eagle, is nearly an herbivore.
It feeds mainly on oily palm nuts.
Sharpest Eyes in the Skies
Most eagles spend their time soaring on air
currents over fields, forests, mountain ridges, or coast lines looking for
food. Like all birds, eagles see in color. Their vision at night is poor, but
during the day all eagles have very sharp eyesight--four to five times stronger
than a human with perfect vision. They can spot movement long distances away.
An eagle can easily see a rabbit on the ground from 300
m up and 1
km away! In order to blink, eagles have a clear, inner
eyelid called a nictitating
membrane.
Eagle’s eyes are almost as big as human eyes but their heads are much
smaller. They can see much better than us and have color vision.
©S.Gettle/GLOBIO.org Why do eagles have such sharp eyesight? Part of the reason is that eagles
have TWO focus areas in each eye! Humans have just one. Eagles have binocular
vision to see forward, the way you do. At the same time an eagle can see
out the side or slightly backwards, which is called monocular
vision. The two types of vision combined help the eagle see small objects
far away.
The Wing’s the Thing
A pair of little eagles flying together. The eagle on the left is a female
and the other is the male. Can you tell the difference between the male and
female?
©Julian Robinson Eagles that live in forests, such as the crested serpent eagle, have short
wings and long tails. These features enable them to twist and turn easily in
the air, an advantage when chasing prey at high speed through tree trunks and
branches. Soaring eagles, such as the golden eagle and Africa's bateleur eagle,
have long wings and short tails. These features let them glide effortlessly
on rising air currents. However, these same features make soaring eagles poor
flyers, so every takeoff and landing is an adventure! As a result, soaring
eagles often hunt from high perches, where they can literally "fall" into
the air and swoop down on unsuspecting fish and mammals.
Feet that Fit the Food
Eagles look similar around the world. They have the same shape, sharp talons,
dagger beak, and keen eyesight. However, each species hunts its home landscape
with special skills. An eagle’s wings and tail might determine
where and how an eagle flies, but its feet tell you what kind of hunter it
is.
Look at the size of this 7-month-old harpy eagle’s talons!
©P.Oxford/Foto Natura/Minden Pictures Harpy Eagles
These six types of eagles are forest-dwelling giants that prey on such large
mammals as deer and monkeys, using the huge, powerful, hooked talons on
their feet.
Serpent eagle’s gripping feet are perfect for hunting snakes but
also great for perching on branches.
©P.Oxford/Minden Pictures Serpent or Snake Eagles
There are 12 species of serpent eagles, also called snake eagles. They perch
on high trees and swoop to capture snakes, frogs, and lizards, even the
poisonous ones! These eagles have gripping feet with needle-like talons
and long legs. The lower section of their legs is not feathered. Instead
it is covered by armor-like scales that help protect against snakebites.
This young golden eagle is now old enough to live away from the nest and
find its own food.
©S.Gettle/GLOBIO.org Booted Eagles
The 30 species of booted eagles have feathers growing down their legs and
covering their toes. This group includes the golden eagle, which is found
around the world and has learned to hunt and eat almost anything it can
catch. Golden eagles eat rabbits, snakes, squirrels, other birds, even
small dogs. In Greece, they even eat turtles, soaring high then crashing
them onto the ground to crack open their shells.
An African fish eagle searches for its next meal.
©G.Ellis/GLOBIO.org Fish or Sea Eagles
Sea eagles’ oily-feathered bodies are perfectly adapted to the life
of a fish hunter. The 11 sea eagles, which include America's beloved bald
eagle, tend to specialize in eating fish and water birds. Feet with spiny
pads, curved claws, and an outer toe help them catch and hold fish. Some
even hunt flamingoes and poisonous sea snakes.
Big Babies in Big Nests
Wedge-tailed eagle males hunt for food for their chicks until they are about
30 days old and then both parents share responsibility for hunting for meals.
©Julian Robinson Each year a pair of eagles may have one or
two eggs, laid in a nest generally made of sticks. Large eagles such as the
bald eagle of North America build nests over 1
m in diameter. Many eagles return to the same nests and continue to add
sticks and branches. Some nests, such as those of the golden eagle, grow as
big as a car! A nest like this can be 100 years old and used by many
eagle pairs over time.
Eagles make some of the most attentive and caring parents of all birds. Eagle
babies, called chicks or eaglets,
take longer than most birds to develop and learn to fly. A golden eagle chick
remains in its nest for over 3 months before it tries to fly.
A Perfect Eagle Environment
Before a bald eagle can build a nest it must choose a location. Nests are
usually built in forests near bodies of water so they can easily fish for
a meal. Humans can create problems for eagles so they don’t usually
live close to people.
©G.Ellis/GLOBIO.org Two things make a perfect environment for
eagles: food to hunt and high places to build nests and raise eaglets safely.
Since eagles can soar great distances searching for prey, their homes may cross
over more than one type of environment. For example, members of the sea eagle
group may hunt over the water, along the shore, or in forests and rivers.
Moving On
In some cases, eagles can move from one environment to another when the season
becomes too cold or hot. While migrating,
eagles such as the bald eagle ride columns of rising air and can average speeds
of 50 kph.
Bald eagles usually migrate in groups called a “stream.” Each
stream can be 40-50
km long, with birds spread out about 1
km apart. Scientists are still trying to understand exactly how eagles
know the migration route and what clues they use to navigate long distances
across the earth.
High-Level Hazard
Habitat loss can disrupt the entire food chain in an area. Eagles are at the top of their food chains, so if their food disappears they have to find somewhere else to hunt, build their nests, and raise their chicks.
©G.Ellis/GLOBIO.org If you are the best aerial hunter in your
environment, and most eagles are, you sit at the top of the food chain. Being
king of the sky can be great, but it can also be dangerous. At the peak of
the food
chain, all the chemicals and pollution in
the environment add up and can be in the food you eat and feed your babies.
This can make eagles very sick or unable to have healthy chicks. Poaching is
also a threat to eagles all over the world, although, most eagles are protected
by special laws and regulations.
Discovery of a Lifetime: A Lost Eagle
On November 3, 1993, American scientist Russell
Thorstrom was walking through the tropical forests of Madagascar when he spotted
one of the six rarest birds in the world. It was a Madagascar serpent eagle,
a species that hadn't been seen in 60 years! However, the nation of 14 million
people, who are known as Malagasys, is very poor. In their struggle to survive,
the Malagasys have logged and cleared much of their nation's forest, destroying
a critical habitat for
the serpent eagle.
When Thorstrom and other biologists returned to the site a few weeks later,
they found nearby forests being burned by local farmers—and no sign of
the eagle. However, more recently researchers have discovered 15 eagles at
nine locations. In 2006 they discovered the first Madagascar serpent eagle
nest.
Eagles Inspire Imagination
This mask is made with an eagle skull and feathers. The Kwakiutal people
of Canada use transformation masks to tell stories and about their culture and history.
©F.Lanting/Foto Natura/Minden Pictures For centuries, people all around the globe
have admired eagles so much that they attributed great powers to the birds.
Eagles’ powerful hooked beaks and sharp talons adorned the flags that
led ancient Roman armies into battle. According to stories In South America,
the spot on which an eagle landed dictated where the ancient Aztecs should
build a city. Today, professional football (soccer) teams in Portugal, Italy,
Greece, Turkey, and Spain have eagle mascots on their uniforms to symbolize
strength and dominance.
Many cultures gathered or even hunted eagles for their beautiful and "powerful" feathers.
Until recently, most cultures believed it was evil or bad luck to kill or injure
an eagle. Eagles are now protected in many areas and can be seen hunting and
nesting in the wild and even sometimes in cities!