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Home » Programs » Eagle Facts → » More About Bald Eagles
More About Bald Eagles
NAME: Bald Eagle or American Eagle
(Haliaeetus leucocephalus)
U.S.A.'S NATIONAL EMBLEM: The Bald Eagle was officially declared the National Emblem
of the United States by the Second Continental Congress in 1782. It was selected by the
U.S.A.'s founding fathers because it is a species unique to North America. Ben Franklin
wanted the wild turkey to be the national bird, because he thought the eagle was of bad
moral character. The Bald Eagle has since become the living symbol of the U.S.A.'s
freedoms, spirit and pursuit of excellence. Its image and symbolism have played a
significant role in American art, folklore, music and architecture.
COLOR & SIZE: The feathers of newly hatched Bald Eaglets are light grey, and turn dark
brown before they leave the nest at about 12 weeks of age. During their third and fourth
years, Bald Eagles have mottled brown and white feathers under their wings and on their
head, tail and breast. The distinctive white head and tail feathers do not appear until Bald
Eagles are about 4 to 5 years old. Their beak and eyes turn yellow during the fourth and
fifth year, and are dark brown prior to that time. Bald Eagles are about 29 to 42 inches
long, can weigh 7 to 15 pounds, and have a wing span of 6 to 8 feet. This makes them one
of the largest birds in North America. Females are larger than males. Bald Eagles residing in
the northern U. S. are larger than those that reside in the south. They have a life span of up
to 40 years in the wild, and longer in captivity.
VOCAL SOUNDS:
Listen to the voice of an eagle. (Quicktime)
The American Bald Eagle has a high-pitched, shrill, and staccato whistle-like voice. The
eagle does not have vocal chords. Instead, the sound is made in the “syrinx”, which is
where the windpipe divides to go to the lungs. The bird’s call is used to either reinforce the
bond between mated eagles or to warn other predators from coming close to their nest
and/or into a territory they will defend. The Bald Eagle has a high yet interesting voice.
HABITAT & RANGE: Bald Eagles live near large bodies of open water such as lakes,
marshes, seacoasts and rivers, where there are plenty of fish to eat and tall trees for
nesting and roosting. Bald Eagles have a presence in every U. S. state except Hawaii. Bald
Eagles use a specific territory for nesting, winter feeding or a year-round residence. Its
natural domain is from Alaska to Baja, California, and from Maine to Florida. Bald Eagles
that reside in the northern U. S. and Canada migrate to the warmer southern climates of
the U. S. during the winter to obtain easier access to food, especially fish. Some Bald Eagles
that reside in the southern U. S. migrate slightly north during the hot summer months.
FOOD SOURCE & FLIGHT: Bald Eagles feed primarily on fish, but also eat small animals
(ducks, coots, muskrats, turtles, rabbits, snakes, etc.) and occasional carrion (dead
animals). They swoop down to seize fish in their powerful, long and sharp talons
(approximately 1,000 pounds of pressure per square inch in each foot). They can carry their
food off in flight, but can only lift about half their weight. Bald Eagles have been recorded at
44 miles per hour in level flight. They seldom dive vertically on their prey, preferring to
decend more gradually and snatch fish, rabbits, etc. with their feet. Their diving speed
is estimated at 75 to 100 miles per hour. They can fly to altitudes of 10,000 feet or more,
and can soar aloft for hours using natural wind currents and thermal updrafts. Bald Eagles
can swim to shore with a heavy fish using their strong wings as paddles. However, it is also
possible that they can drown if the fish weighs too much.
NESTING & BREEDING: Bald Eagles are monogamous and mate for life. A Bald Eagle will
only select another mate if its faithful companion should die. They build large nests, called
eyries, at the top of sturdy tall trees. The nests become larger as the eagles return to breed
and add new nesting materials year after year. Bald Eagles make their new nests an
average of 2 feet deep and 5 feet across. Eventually, some nests reach sizes of more than
10 feet wide and can weigh several tons. When a nest is destroyed by natural causes it is
often rebuilt nearby. Nests are lined with twigs, soft mosses, grasses and feathers. The
female lays 1 to 3 eggs annually in the springtime, which hatch after about 35 days of
incubation. Hunting, egg incubation, nest watch, eaglet feeding and eaglet brooding duties
are shared by both parents until the young are strong enough to fly at about 12 weeks of
age. Eaglets are full size at 12 weeks of age. Only about 50% of eaglets hatched survive
the first year.
POPULATION SIZE & DECLINE: Bald Eagles were once very common throughout most of
the United States. Their population numbers have been estimated at 300,000 to 500,000
birds in the early 1700s. Their population fell to threatened levels in the continental U.S. of
less than 10,000 nesting pairs by the 1950s, and to endangered levels of less than 500
pairs by the early 1960s. This population decline was caused by humans. The mass
shooting of eagles, use of pesticides on crops, destruction of habitat, and contamination of
waterways and food sources by a wide range of poisons and pollutants all played a role in
harming the Bald Eagle's livelihood and diminishing their numbers. For many years the use
of DDT pesticide on crops caused thinning of eagle egg shells, which often broke during
incubation.
RECOVERY & PROTECTION: Strong endangered species and environmental protection
laws, as well as active private, state and federal conservation efforts, have brought back
the U.S.A.'s Bald Eagle population from the edge of extinction. The use of DDT pesticide
was outlawed in the U.S. in 1972 and in Canada in 1973. This action has contributed greatly
to the return of the Bald Eagle to America's skies.
The Bald Eagle was listed as Endangered in most of the U.S. from 1967 to 1995, when it
was slighted upgraded to Threatened in the lower 48 states. The number of nesting pairs of
Bald Eagles in the lower 48 states had increased from less than 500 in the early 1960's to
over 10,000 in 2007. They had recovered sufficiently to delist them from Threatened status
on June 28, 2007.
Since delisting, the primary law protecting Bald Eagles has shifted from the Endangered
Species Act to the Bald and Golden Eagle Act. Although Bald Eagles have made an
encouraging comeback throughout the U.S.A. since the early 60s, they continue to be face
hazards that must be closely monitored and controlled. Even though illegal, Bald Eagles are
still harassed, injured and killed by guns, traps, power lines, windmills, poisons,
contaminants and destruction of habitat.
Yet, there is much less funding to provide for their needed management and protection.
Public awareness about their status, strict enforcement of protective laws, preservation of
their habitat, and support for environmental conservation programs are needed to assure a
healthy and secure future for the U.S.A.'s majestic and symbolic national bird.
Updated 12/06/07
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