Sunday, 1 May 2011

Report Text_Bald Eagles @globio.org

Bald Eagles

A Proud and Powerful Bird

The most recognizable eagle in North America is the bald eagle. A large powerful predatory bird, bald eagles are a type of fish eagle. They fly low over the water and snatch up fish with their powerfultalons. Adult bald eagles are dark brown to black. They have a distinctive white head and a sweeping wingspan of 2.5 m. They live all across North America, especially near wetlands and coasts. Bald eagles were once endangered throughout most of their range but are making a comeback.
Bald Eagle

Where Eagles Fly

Bald eagles are found in Canada, northern Mexico, and every state of the United States except Hawaii. They usually travel and gather in small flocks or remain solitary.  In a few locations, where foods such as salmon are plentiful in late winter, thousands of bald eagles will gather. One such place is the Chilkat Bald Eagle Preserve, in southeastern Alaska, U.S.A., where over 3,000 birds sometimes gather.

Strong and Lightweight

Bald eagle bodies are light (less than 6.5 kg) and strong - two features that are perfect for flying and for catching prey. The lightness of their bodies allows them to get off the ground and fly high, so they can look down and hunt for prey. Their strength is important for diving down, seizing prey, and carrying it away.
Bald eagles are large and powerful birds – to discover more click below.
©G.Ellis/GLOBIO.org

Dive-bombing for Dinner

Eagles feed mainly on fish. But they will also eat water birds, small mammals, and carrion. Eagles can carry off a fish that weighs half as much as the eagle itself! Eagles can fly up to 48 kph and can dive at speeds up to 160 kph. Their keen eyesight allows them to spot fish at distances of up to 1.5 km.

Big Birds Need Big Nests

Bald eagles mate for life, but they may separate briefly during the non-nesting season. They make their nests, called aeries,in tall trees near large bodies of water or wetlands. They use sticks, soft mosses, feathers, grasses, and leaves to build their nests.
They come back to the same nest every year. Each year they add new material to make the nest bigger and more comfortable. Eagle nests can reach up to 3 m across and 1 m high. They can weigh about as much as a car! If storms or other natural causes destroy the eagles’ nests, they often rebuild in a tree nearby. In winter, mostmigrate to a winter feeding ground. A few bald eagles may live year-round in one place if all the conditions are right.
Eaglets
Young eaglets leave the nest when they are 12-15 weeks old.  Until this time and sometimes even after, young eagles depend on their parents for food and protection.
©Tom & Pat Leeson

Nesting: The Creative Way

If there are no trees, some eagles will make their nests on whatever they find - on the top of old telephone poles, dock pilings, ship masts, even light posts. Bald eagles will sometimes nest on the ground. They only do this on islands or other places where there are no trees and no predators on the ground.

From Eaglet to Eagle

After an eagle pair builds a nest, the female lays one to three eggs in the spring. The parents incubate the eggs for about 35 days before chicks hatch. Both eagle parents share the duties of hunting, incubating the eggs, watching the nest, and feeding and caring for the babies, or eaglets. Many times, only the strongest eaglet will survive the first few weeks of life. When an eaglet is strong enough, it will learn to fly. Usually after 12 to 15 weeks, an eaglet is fully-grown and leaves the nest for good.
Eagle chick
Eagle chicks hatch 35 days after an egg is laid.  They are covered in soft fuzzy feathers. Their parents feed them fish and meat that they’ve caught and torn up into bite-sized pieces.
©Tom & Pat Leeson
Young bald eagles start out with a mixture of brown and white coloring all over their bodies. Their beaks are black. After four to five years, they grow dark feathers on their bodies and white feathers on their heads, necks, and tails. Their beaks turn bright yellow. Many people are surprised to learn that bald eagles are not bald. The term “bald” comes from the Old English word balde (BAWLD), which means “white.” 

The Sign of a Healthy Environment

As predators, eagles are at the top of the food chain. If bald eagles are healthy it means the surrounding wetland or coastal environment is probably healthy, too.  Scientists watch eagles closely for signals about the health of the environment.
As predators, eagles are at the top of the food chain. If bald eagles are healthy it means the surrounding wetland or coastal environment is probably healthy, too.  Scientists watch eagles closely for signals about the health of the environment.

An Important Symbol

Native American peoples have a special respect for the bald eagle.  Different native cultures across North America have legends about bald eagles. The stories tell the role eagles have played in the cultures’ histories. Along the West Coast, several cultures honor eagles by carving them into large wooden totem poles. The bald eagle is also the national bird of the United States of America.
Drawing
Native Americans carved images of bald eagles at the top of totems (second and fourth totem from right) to show their powerful position in the world. This drawing by Gordon Miller is based on a photograph of the Haida Gwaii village at Ninstints on Queen Charlotte Island, B.C., Canada. The photograph was taken in 1913 by photographer C.F. Newcombe.
©Gordon Miller

Bald Eagles Under Threat

Human-made poisons can affect bald eagles. One of the greatest threats to bald eagle populations in the past hundred years was the use of the pesticide DDT. Farmers used this pesticide to control insects that were damaging their crops. Unfortunately, the pesticide also made its way into wetlands. It got into the bodies of the fish that bald eagles ate. The poison made the eagles’ eggshells very thin. When the parents sat on the eggs to incubate them, the shells were crushed.
Eagle Nest
Bald eagles build large nests made of sticks and other materials.  A nesting pair will use the same nest year after year, adding new materials to make it bigger each season.  They usually nest in the top of tall trees.
©M.Quinton/Minden Pictures

Protecting the Bald Eagle

At one time, hunting and pollution had reduced the number of bald eagles to about 2,000. Hunting bald eagles in the United States was banned in 1940. In 1972, the United States banned DDT. These bans have helped the bald eagle population recover. Protective conservation laws have also helped bald eagles bounce back. Today, over 35,000 bald eagles can be seen flying over Canada and the United States.

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