Bald Eagle

Haliaeetus leucocephalus

U.S. Fish & Wildlife Service

The bald eagle is truly an all- American 

bird. It ranges over most of the 

continent, from the northern reaches of 

Alaska and Canada down to northern 

Mexico. 

While our national symbol was in 

danger of extinction throughout most 

of its range 30 years ago, the bald eagle 

has made a tremendous comeback, 

its populations greatly improving in 

numbers, productivity, and security in 

recent years. 

Juvenile bald eagles have mottled 

brown and white plumage, gradually 

acquiring their dark brown body and 

distinctive white head and tail as they 

mature. Bald eagles generally attain 

adult plumage by 5 years of age. Most 

are capable of breeding at 4 or 5 years 

of age, but in healthy populations they 

may not start breeding until much 

older. Adults weigh 8 to 14 pounds 

(occasionally reaching 16 pounds in 

Alaska) and have wingspans of 5 1⁄2 to 

8 feet. Those in the northern range 

are larger than those in the south, and 

females are larger than males. 

Bald eagles can live 15-25 years in the 

wild, and even longer in captivity. They 

typically mate for life and build huge 

nests in the tops of large trees near 

rivers, lakes, marshes, or other aquatic 

areas. Nests are often re-used year 

after year, with additions to the nests 

made annually. Nests are often 4 to 6 

feet wide and may weigh up to 1,000 

pounds. Although bald eagles may 

range over great distances, they usually 

return to nest within 125 miles of where 

they were raised. 

Breeding bald eagles typically lay 

one to three eggs once a year, which 

hatch after about 35 days. The young 

eagles are flying within 3 months and 

are on their own about a month later. 

However, disease, lack of food, bad 

weather, or human interference can kill 

many eaglets; recent studies show that 

approximately 70% survive their first 

year of life. 

The staple food of most bald eagle 

diets is fish, but they will also feed on 

waterfowl, rabbits, snakes, turtles, 

other small animals and carrion. In 

winter, eagles that nest in northern 

areas migrate south and gather in large 

numbers near open water areas where 

fish and other prey are plentiful. Eagles 

that nest in the south during the winter 

migrate north in the summer where 

food is plentiful. 

Wildlife experts believe there may 

have been 100,000 nesting bald eagles 

in the lower 48 states when the bird 

was adopted as our national symbol in 

1782. Since that time, the bald eagle 

has suffered from habitat destruction 

and degradation, illegal shooting, and 

contamination of its food source, most 

notably due to the pesticide DDT. By 

1963 there were only 417 bald eagle 

nesting pairs in the lower 48 states. 

Bald eagles have few natural enemies. 

In general they prefer an environment 

of quiet isolation; tall, mature trees; and 

clean waters. Those conditions have 

changed over much of the bald eagle’s 

former habitat. 

Although primarily fish and carrion 

eaters, bald eagles and other raptors 

were seen as marauders that killed 

chickens, lambs, and other domestic 

livestock. Consequently, large numbers 

were shot by farmers, ranchers, and 

others. 

In 1940, noting that the national bird 

was “threatened with extinction,”

Congress passed the Bald Eagle 

Protection Act prohibiting, except 

under certain specified conditions, 

the taking, possession, and commerce 

of bald eagles. A 1962 amendment to 

this Act added the golden eagle, and 

the amended law became known as 

the Bald and Golden Eagle Protection 

Act. In 1967, bald eagles were officially 

declared an endangered species (under 

a law that preceded the Endangered 

Species Act of 1973) in all areas south of 

the 40th parallel.

The greatest threat to the bald eagle’s 

existence arose from the widespread 

use of DDT and other pesticides after 

World War II. DDT was used for insect 

control throughout the country and 

its residues washed into lakes and 

streams. There, it was absorbed by 

aquatic plants and animals that were 

eaten by fish. The contaminated fish, in 

turn, were consumed by bald eagles. 

The chemical interfered with the bald 

eagle’s ability to develop strong shells 

for its eggs. As a result, bald eagles and 

many other bird species began laying 

eggs with shells so thin they often 

broke during incubation or otherwise 

failed to hatch. Their reproduction 

disrupted, bald eagle populations 

Bald eagles are frequently seen perched 

on large snags above lakes or rivers. 

From this vantage point they can 

survey their surroundings for prey
plummeted. As the dangers of DDT 

became known, in large part due to 

Rachel Carson’s famous book Silent 

Spring, this chemical was banned for 

most uses in the U.S. in 1972. 

In addition to the adverse effects of 

DDT, bald eagles also died from lead 

poisoning as a result of feeding on 

hunter-killed or crippled waterfowl 

containing lead shot and from lead shot 

that was inadvertently ingested by the 

waterfowl. In 1991, a 5- year program 

to phase out the use of lead shot for 

waterfowl hunting was completed by 

the Service .

Gradually, the Service assembled 

the largest colony of breeding bald 

eagles in captivity at its Patuxent 

Wildlife Research Center near Laurel, 

Maryland, in a major effort to return 

healthy eagles to the wild. The center is 

now run by the U.S. Geological Survey. 

Patuxent’s scientists enhanced the 

species’ breeding potential by removing 

the eagle’s first clutch of eggs and 

incubating them artificially. The 

eagles would usually then lay a second 

clutch, which the birds were allowed 

to incubate themselves. In all, 124 bald 

eagles were hatched at Patuxent. 

These captive-hatched bald eagles were 

an important source for restocking 

wild populations in certain areas of the 

country and helped to reestablish 

a broader distribution. Patuxent’s 

program came to an end in 1988 as 

bald eagles began to reproduce more 

successfully in the wild and the center 

turned its efforts toward other more 

critically endangered species. 

Some states, universities, and nonprofit organizations have continued 

reintroduction efforts. Two methods 

are generally used. Eaglets used for 

reintroduction may be captive hatched 

or, since usually only two young per 

nest survive, they may be transferred 

from a bald eagle nest with a clutch of 

more than two. These “extra” eaglets 

are placed in the nest of an adult pair 

whose own eggs are infertile or fail to 

hatch. The “foster parents” readily 

adopt the chicks and raise them as their 

own.

Another method, called “hacking”, 

involves placing eaglets in manmade 

towers at 8 weeks of age. These towers 

are located in remote areas where 

bald eagle populations are low or nonexistent. The eaglets are kept in an 

enclosure and fed by humans who stay 

out of sight. When the birds are capable 

of flight, at about 12 weeks old, the 

enclosure around the artificial nest is 

opened and the birds are free to leave. 

Food is still provided at the release 

site until the birds learn to fend for 

themselves in the wild. 

Thanks to the banning of DDT and 

these other recovery methods, bald 

eagle populations have steadily 

increased in the past 25 years. From 

417 nesting pairs in the early 1960s, 

there are now approximately 7,066 bald 

eagle nesting pairs and an unknown 

number of immature bald eagles in 

the conterminous U.S. In the last few 

years, several states have had breeding 

bald eagles for the first time in years. 

The bald eagle was originally listed as 

endangered under the Endangered 

Species Act in 43 of the lower 48 states 

and listed as threatened in Michigan, 

Minnesota, Oregon, Washington, and 

Wisconsin. (There are about 40,000 

bald eagles in Alaska and none in 

Hawaii.) “Endangered” means a species 

is considered in danger of extinction 

throughout all or a significant portion 

of its range, while “threatened”

is a less dire category, meaning a 

species is considered likely to become 

endangered within the foreseeable 

future, but is not currently in danger of 

extinction. 

In July 1995, the Service announced 

that bald eagles in the lower 48 

states had recovered to the point 

that those populations that were 

previously considered endangered 

were now considered threatened. 

The Service then formally upgraded 

those populations from endangered to 

threatened.

In July 1999, the Fish and Wildlife 

Service proposed to remove the bald 

eagle from the list of threatened and 

endangered species. Since then, the 

Service has reviewed the comments 

received on that proposal along with 

new data and information to determine 

the best ways to manage for the species 

once it is removed from the protections 

of the Endangered Species Act. In 

2006, the Fish and Wildlife Service 

re-opened the public comment period 

due to new information on the proposal 

to delist. Data gathered during this 

comment period will be factored into 

a final decision on the status of the 

species. 

U.S. Fish & Wildlife Service

http://www.fws.gov

June 2006

Bald eagles normally lay two to three 

eggs a year, which hatch after about 

35 days. The eagles learn to fly within 

three months and are on their own 

about a month later.

As a recovery method, biologists place 

eagles into the nest of adult pairs whose 

own eggs failed to hatch. The pair then 

serve as “foster parents.”