Facts About Bald Eagles

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Facts About Bald Eagles

Post by jkr » Sun Feb 11, 2018 7:40 am

Frequently Asked Questions about the Bald Eagle

What does a Bald Eagle look like?
Adult Bald Eagles have white heads and tails and dark brown bodies. They have large yellow feet with sharp talons and a large yellow beak and yellow eyes. They can weigh up to 14 pounds (6.5 kg) and their wings can stretch to over 7 feet (2 metres) across.

Why are they called Bald Eagles?
Bald Eagles are not bald at all, but have a white head. Hundreds of years ago the English word for WHITE was BALDE and the word piebalde meant mottled with white, so the eagles with white heads were called Balde Eagles.

Where do Bald Eagles live?
Bald Eagles live primarily along the waterways: the seashore, lakes, rivers and ponds. Bald Eagles live only in North America and all the way from Alaska to Florida, but mainly along the northwestern coast of the USA and Canada.

How long do Bald Eagles live?
Bald Eagles kept in captivity may live 40 years or more. Although we don’t know for sure, we think that in the wild Bald Eagles may live to be 30 or a little older.

What do Bald Eagles eat?
Bald Eagles are primarily scavengers. Whenever possible they find and eat dead food like spawned-out salmon or road-killed animals. Their favourite food is fish, but they will eat small mammals like rabbits and water birds like ducks or gulls.

How well can a Bald Eagle see?
Bald Eagles see about 7 times better than people can. One thousand feet (300 metres) up in the air, a Bald Eagle can spot its prey over 3 square miles (8 square km). They are able to do this because they can see both forward and sideways at the same time. They have binocular vision where both eyes focus forward on a single item and this permits very accurate depth perception. Each eye can also see out the side. This is monocular vision and is very efficient at detecting motion.

What kind of sound does a Bald Eagle make?
Bald Eagles do not have very many kinds of calls. Their voice sounds something like a gull’s scream but in a series of notes. The female tends to have a lower sounding voice, while the male’s voice is higher and more like a scream.

How many feathers does a Bald Eagle have?
Bald Eagles have between 7000 and 7200 feathers.

How fast can a Bald Eagle fly?
A flying Bald Eagle can reach speeds of about 75 miles (120 km) per hour. When going long distances or just moving around their territory they tend to fly 20–30 miles (30–50 km) an hour.

Do Bald Eagles sweat when they get hot?
No, they have no sweat glands. To cool themselves, they open their mouths and pant. They also will hold their wings out from the body to let the cool breeze get closer to their hot 107 degree F (42 degrees C) body.

How much food does a Bald Eagle eat in one day?
They eat approximately ½ to 1 ½ pounds (200 to 700 grams) daily.

Do the mother and father Bald Eagle stay together for life?
Yes, Bald Eagles mate for life, as do most birds. However, if one dies or is lost, the one remaining will take a new mate.

Where does a Bald Eagle build its nest and how big is it?
Bald Eagles build their nests near water and primarily in very tall trees, usually 50–150 feet (15–45 metres) tall. If they live where there are no tall trees, such as Alaska or Florida, they may build the nest on a cliff or a shorter tree. Their nests are usually about 4 to 5 feet (1.5 metres) across but have been known to be 10 feet (3 metres) across. The nest can weigh up to 1000 pounds (450 kilograms) and is so strong that a human would be able to stand in it without breaking the nest.

How many eggs does a Bald Eagle lay?
The female Bald Eagle lays 1 to 3 eggs, but usually 2 eggs. The eggs are off-white in colour and about 3 inches (7.6 cm) long.

Why do Bald Eagles have such big, strong nests when they have only two small eggs?
Bald Eagles are about 3 feet (90 centimeters) from their head to their tail and before the nestlings leave the nest, they become as large as their parents and need a lot of room for their 6 foot (1.8 metre) wingspan. The nests need to be very sturdy because the eaglets jump up and down, flapping their wings when they’re learning to fly.

When do the eggs hatch?
The parents take turns sitting on the eggs for about 35 days. The hatchlings weigh about 3 ounces (85 grams) and have grey down feathers all over. The eaglet’s feathers start to come in when they are four or five weeks old. The first egg laid will be the first egg to hatch and therefore the oldest eaglet may be a little larger and better able to fight for food than the younger ones.

How long do the nestlings stay in the nest? When do they learn to fly?
Eaglets stay in the nest and are fed by their parents for 12 to 14 weeks. They practice flapping their wings and hopping in the nest, often jumping up to other branches, called branching, close to their nest. After days or weeks of jumping, flapping and branching, they fly off the nest. This first flight is called “fledging.”

How long is it before the chicks look like their parents?
It takes a juvenile (who is between 1 and 4 yrs old) eagle about 4–6 years before they get all their adult feathers and coloring. Until then, they have brown bodies including their head and tail, with some white feathers mixed in and they have brown eyes and beak and bluish feet.

Why do the chicks sometimes have a bulge on their chest?
That bulge is where the bird’s crop is. The crop is a little sack that is attached to their esophagus, the tube that goes from their mouth to their stomach. An eagle can swallow large chunks of food that are held in the crop until there is room in the stomach. You might see an eaglet or adult moving its neck in a funny way to help the food move from the crop to the stomach. Eagles need to eat fast and this is a place to store their food.

How can you tell the difference between the mother and father eagle?
Male and female eagles have the same coloring but are different in size. Females are about 1/3 larger than males and the female’s call is generally lower pitched than the male’s call, which is almost a scream. Another way to tell them apart is to measure the height of their bill. The female’s bill is always deeper than the male’s and usually has a larger hook than the male’s.

Can Bald Eagles swim?
They are very good swimmers. Sometimes an eagle will catch a fish in its talons that is too heavy for them to carry and they will swim to shore with it so they can eat it.

What are a Bald Eagle’s enemies?
Sometimes a raccoon or other large bird, like an owl, may attack a nestling, but human beings are the eagle’s main enemy. Humans use chemicals and these poison the eagles food supply. Automobiles sometimes strike eagles that are feeding on a road kill. Eagles sometimes fly into high power lines and break their wings. The biggest threat to eagles is a poisoned food supply and then the loss of suitable nest trees.

Are there very many Bald Eagles?
Bald Eagles were put on the official US Endangered Species list about 30 years ago (1976) and about 10 years ago (1995) they were upgraded to Threatened, because their numbers have been increasing. There are now an estimated 70,000 Bald Eagles in the world, with about 35,000 living in Alaska and 20,000 living in British Columbia. This year (2007) the US will decide if they will remove the Bald Eagle from the federal list of Threatened and Endangered species.
Judy (jkr) - member since 2006
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Re: Facts About Bald Eagles

Post by jkr » Sat Apr 07, 2018 6:42 am

Nest Building Facts

The bald eagle builds the largest nest of any North American bird, up to 13 feet deep, 8.2 feet wide, and 1.1 tons in weight.

A typical nesting landscape is usually forested and include areas of water. These landscapes provide for basic needs: water to drink, fish to eat, forest trees for shelter and a place to raise young, and perches for hunting and resting. With the increasing population of eagles many are becoming urbanized so it is not unusual to see eagles nesting within communities near water sources.

Together, the male and female bring new sticks to strengthen the structure, and also grass-like material to form a soft cup in the center of the nest where the eggs will rest.

Some pairs need to rebuild their nest almost from scratch if winds and bad weather have damaged it. This nesting activity starts one to three months before the female lays eggs.

Bald eagle's large nest is called an aerie. A typical nest will range from 1.8 to 3 meters (6-10 feet) in diameter and about 1.8 to 3 meters (6 to 10 feet) high. The nest cavity, where the eggs are laid, will be about 30 to 40 centimeters (12 to 16 inches) in diameter and about 10 centimeters (4 inches) deep.

First year nests are usually smaller, and the nest size will increase each year as eagles re-use the nest and add sticks to it.

Bald eagles are very territorial birds, and most breeding pairs return to the same nest site year after year. They may use the same nest annually for as many as 35 years, or they may build additional nests in their nesting territory, and alternate the use of them from year to year.

Bald eagles generally nest near coastlines, rivers, and large lakes where there is an adequate food supply.
In areas where trees are few and far between eagles will nest on the ground or on the tops of cliffs!

Ground nests are built of whatever's available, such as kelp and driftwood near coastal shorelines.

They nest in mature or old-growth trees, snags (dead trees), cliffs, and rock promontories. In forested areas, bald eagles often select the tallest trees with limbs strong enough to support a nest that can weigh more than 1,000 pounds.

Nest sites typically include at least one perch with a clear view of the water, where they forage.

Eagle nests are constructed with large sticks, and may be lined with moss, grass, plant stalks, lichens, seaweed, or sod.

Bald eagles pick up broken sticks from the ground, and sometimes break branches off trees. They naturally take as many sticks as they can find close to the nest, but may lug some branches as far as a mile, carrying them in their talons.

They usually start building in the top quarter of the tree, below the crown, near the trunk, where branches are thick and strong enough to support the heavy nest. They interweave the sticks, and fill in spaces with grasses, mosses, cornstalks, Spanish moss, and other fibers.

Throughout the season, and sometimes even during fall and winter, eagles keep adding sticks to the nest, and they reuse nests, continuing to build on to them, for many years. The average eagle nest is only 1.5-1.8 meters in diameter and 0.7-1.2 meters tall.

Both sexes bring materials to the nest, but the female does most of the placement. They weave together sticks and fill in the cracks with softer material such as grass, moss, or cornstalks.

Eagles tend to nest in tall, sturdy conifers that stick up above the forest canopy, providing easy flight access and good visibility.

Nesting behavior starts with some clearing out any unwanted debris, fixing any damaged areas of the nest, and adding on. The early season work is usually sporadic and not terribly serious.

Some non-migratory pairs may stay in the vicinity of their territory all winter and can be seen working on their nest sporadically all year long.

The renovation behavior makes the nest ready to house the next generation of eagle young and is part of the courtship process as it strengthens the bond between mates.

Eagles need some degree of insulation and isolation from human activity, though sensitivity to disturbance seems to vary widely.

The nest itself needs to be higher than the surrounding vegetation to provide both easy access and a clear view of possible threats to the nest.

The trees that are tall and strong enough to satisfy eagle nesting needs tend to be old and sometimes may be nearing the end of their life. Occasionally, the nest tree dies but stays strong for a time and the eagles will continue to use their nest, despite the death of the nest tree, often until the tree or nest falls down.

Pairs building a completely new nest often dedicate much of their springtime activities to carrying nesting material and working on the new nest.

The part of the nest where the eggs will be laid is called the bole, or cup, and is lined with softer materials and eagle down feathers.

The nest is constantly being upgraded and rearranged according to available components. The nest grows larger and heavier during the nesting season and as the years pass.

Tree shape, size, and location are more important to an eagle looking to build a new nest than is the tree species, but some of the trees more likely to meet nesting needs are pines, spruces, firs, oaks, and cottonwoods.

Bald eagles usually like to have a clear view in all directions around their nests.

Nest trees tend to be the tallest in the surrounding area, called super-canopy trees. Nests tend to be very large and rather heavy, so the best nest trees are tall, strong healthy trees.

Pairs that are building a new nest usually choose a living tree as the base for their nest though there are often some dead trees, called snags, nearby that serve as lookout posts.

Some eagle pairs build an alternate nest (usually within a mile from first nest) within the eagle territory, and the pair may take turns nesting between these from year-to-year.

When an eagle nest blows down, the eagle pair will usually build another nest nearby.

Because some eagle nests are so large, it is not unusual to be able to spot these nests with a naked eye from a mile away.
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