Large, striking and charismatic birds of prey, the bald eagle,
golden eagle and osprey seem to embody power and majesty.
All regularly occur in Pennsylvania, but only the bald eagle
and osprey nest here. The golden eagle migrates through the
state on a pathway connecting its breeding and wintering
territories.
In the not so distant past, direct persecution and
environmental contaminants drove eagle and osprey
populations to catastrophically low levels. Protection at both
state and federal levels, tremendous conservation efforts
and improved waterway quality enabled them to rebound in
Pennsylvania and elsewhere.
While persecution and environmental contaminants continue
to impact these large raptors, today’s primary threats include
loss of habitat due to land-use changes and declining habitat
quality.
Taxonomists place bald and golden eagles in the same family
as hawks, kites, harriers and Old World vultures – the family
Accipitridae. The osprey is the only species of the family
Pandionidae.
Bald Eagle
The bald eagle’s scientific name, Haliaeetus leucocephalus,
means “white-headed sea eagle.” The word “bald” is a
misnomer. The mature eagle’s head is covered with gleaming
white feathers. Its body is dark brown, its tail white.
Immatures are brown, mottled with white on their wings and
body. Full adult plumage is attained in the fifth year. Both
adults and immature bald eagles have yellow bills and feet,
and their legs are feathered halfway down.
Bald eagles were listed as a federally endangered species until
1995, when their status was upgraded to “threatened.” In
2007, following a remarkable population recovery, the bald
eagle was removed from the federal List of Endangered and
Threatened Wildlife in the lower 48 states. Although no longer
listed at the federal level, the bald eagle remains protected
under the federal Bald and Golden Eagle Protection Act, the
Lacey Act and the Migratory Bird Protection Treaty Act. In
Pennsylvania, the bald eagle is given additional protections
under the state Game and Wildlife Code.
Adult bald eagles are 30 to 40 inches in length and weigh 8
to 14 pounds. Their wingspans are 6 to 8 feet, and they stand
about 2 feet tall. As with other birds of prey, the female is
larger than the male.
Bald eagles fly with strong, deep strokes, or soar on flattened
wings. Their eyesight is among the keenest in the animal
world, five or six times sharper than a human’s. A bald eagle’s
call is a rapid, harsh cackle, kweek-kik-ik-ik-ik-ik, or a lower
kak-kokkak.
Fish, either caught live or scavenged as carrion, make up 60
to 90 percent of a bald eagle’s diet. Bald eagles also eat birds,
small mammals, reptiles, amphibians and invertebrates. Eagles
soar above the water or sit on a perch, and when they spot a
fish near the water’s surface, they swoop down and snatch it
in their talons. They use their talons for killing, and their heavy
bills for tearing prey apart for eating. Sometimes an eagle
will go after an osprey or another fish-eating bird, forcing it
to drop a captured fish, which the eagle grabs in midair. This
behavior is known as “pirating” prey.
Generally, bald eagles mate for life, although when one
partner dies, the other quickly finds a new mate if one
is available. Nesting is preceded by a spectacular aerial
courtship, with the birds locking talons, diving and
somersaulting in the sky.
Eagles & Osprey
More Wildlife Notes are available from the Pennsylvania Game Commission, Bureau of Informaon
and Educaon, 2001 Elmerton Ave., Harrisburg, PA 17110-9797. www.pgc.pa.gov
Revised 02/2021
WILDLIFE NOTE
An eagle’s nest is called an eyrie. The big raptors choose large,
sturdy trees with good views of their surroundings. Nest sites
are near lakes, rivers, reservoirs, and seashores.
A new nest is about 5 feet wide and 2 feet high, with an inside
depression 4 to 5 inches deep and 20 inches in diameter.
Often a pair returns to the same nest year after year, repairing
damage and adding a new layer of sticks, branches and
cornstalks, plus a lining of grass, moss, twigs and weeds.
Enlarged annually, some nests grow so big and heavy that they
break the branches or tree supporting them. Unlike ospreys,
bald eagles are not likely to build on artificial structures,
although a few have done so in Pennsylvania.
The female lays two eggs (sometimes only one and
occasionally three) during the span from February through
April. Eggs are about 2¾ by 2½ inches, dull white and
unmarked. Both parents incubate, with the pair taking
turns at the nest.
If all goes well, the eggs begin hatching after
about 35 days. Young birds (eaglets) are fed by
their parents. Because eggs hatch over several
days, age and size differences among
hatchlings often gives the first
hatchling a head start and a
competitive advantage at feeding
time. A large, healthy eaglet might
kill a smaller, weaker one or out-
compete it for food.
Eaglets develop most of their
feathers by 3 to 4 weeks, walk in
the nest at 6 to 7 weeks, and
begin to fly at about 3 months.
Young separate from their
parents in autumn.
Factors affecting nest success
are many. Bald eagle nests
and young eagles are easily
disturbed and nest failure can occur
when people get too close to an
active nesting area. Adults might
abandon a nest site altogether or
leave eggs or hatchlings exposed
to sun, cold temperatures, severe
weather and predators. Also, when
growing eaglets are disturbed before
their first flight, they may fledge prematurely which
makes them vulnerable to terrestrial predators and inclement
weather. To protect eagles, people should keep their distance
from active nests, roost sites or feeding areas, and avoid
approaching a nest directly. Federal regulations prohibit any
intrusion within 660 feet of the nest.
Eagles do not breed until 4 or 5 years of age. Their natural
reproduction rate is slow. High water quality, riparian forest
and wetland habitat are vital for Pennsylvania’s breeding
eagles. Breeding habitat – tall, sturdy trees near bodies
of water in protected areas—continues to dwindle. Toxic
chemicals introduced into the environment cause repeated
nest failures.
Bald eagles are now fairly widespread in Pennsylvania, and
may show up here in all seasons, and particularly along major
river systems. Nesting pairs might remain in their territories
year-round. Many eagles migrate through the state, some
from the north and others from southern parts of the United
States. In fall, bald eagles are among the earliest raptors to
pass through, soaring on thermals over mountain ridges and
along large streams. Many of the early migrants are southern
bald eagles that have wandered north into Pennsylvania and
other northeastern states following nesting and are returning
south again. During winter, bald eagles are seen around
water bodies across the state. During colder winters, when
open water is rare, eagles congregate in areas where
water remains unfrozen and they can forage.
Bald eagles congregate at several locations
in winter, including sites along the lower
Susquehanna River, upper Delaware River,
Raystown Lake, and the reservoirs and
wetlands of northwestern Pennsylvania. In
order to record wintering eagle populations
and to get a preview of nesting behavior,
the Game Commission each year
coordinates a mid-winter bald
eagle survey in cooperation with
volunteer eagle-watchers and the
U. S. Army Corps of Engineers.
While bald eagles today appear in
Pennsylvania in good numbers, not
so very long ago, the future for
the state’s eagles looked bleak. In
1983, when the Game Commission
launched what would be a seven-
year restoration program, only three
pairs of nesting eagles remained in the
state—all of them located in Crawford
County, in northwestern Pennsylvania
along the Ohio border.
As part of a federal restoration
initiative, the Game
Commission sent employees
to the Canadian province
of Saskatchewan to obtain
eaglets from wild nests. From
1983 to 1989, 88 eaglets were brought to Pennsylvania,
where they were raised in specially constructed towers and
released into the wild through a process known as “hacking.”
Hacking is a falconer’s term for maintaining a young bird in a
semi-wild condition, providing food until it can fend for itself.
Pennsylvania’s reintroduction effort jump-started a remarkable
recovery.
By 1998, Pennsylvania was home to 25 pairs of nesting bald
eagles. Within the next three years, the number of nesting
pairs doubled. By 2006, more than 100 nests were confirmed
statewide. And the number of nests topped 250 in 2013, with
A bald eagle’s head
feathers change as
it matures.
Pennsylvania Game Commission | www.pgc.pa.gov
Managing and protecting wildlife and their habitats while promoting hunting and trapping for current and future generations.
bald eagles nesting in all but a handful of the state’s counties.
The nesting population continues to grow in size and expand
in geographical range, and a lot of good habitat remains.
Bald eagles can live 32 years or longer in the wild. They
have few natural enemies and mortality is often directly or
indirectly related to humans. They are sometimes killed by
motor vehicles, occasionally shot and some get lead poisoning
from ingesting contaminated prey. Eagles are sometimes
electrocuted when they land on powerlines, and are at risk of
colliding with wind turbines on ridgetops during migration.
The bald eagle was chosen the United States’ national symbol
in 1782. At that time, an estimated 100,000 lived in what is
now the lower 48 states. In 2007, the U.S. Fish and Wildlife
Service estimated that at least 9,789 nesting pairs populated
the contiguous United States.
Golden Eagle
The golden eagle, Aquila chrysaetos
is a magnificent predator of remote,
mountainous areas. The species occurs in
Europe, Asia, northern Africa and North
America, where it’s most common in the
western United States, Canada and Alaska.
The golden eagle is rare in the Northeast.
A small population exists in
eastern North America. This
geographically isolated population
breeds in northeastern Canada in
the northern forests of Quebec,
Labrador and northern Ontario.
The eastern golden eagle is
closely linked to the Appalachian
Mountains where it travels the
mountain ridgelines during
southbound and northbound
migrations and spends the winter
on the steep forested ridges of the
central and southern Appalachians,
primarily in Virginia and West
Virginia. Pennsylvania hosts its share
of migrating and wintering golden eagles, mainly in the Ridge
and Valley Province between the Allegheny Front and the
Kittatinny Ridge.
Pennsylvania’s Wildlife Action Plan designates the golden
eagle as a vulnerable species, and as a top predator, it is an
indicator of habitat quality.
Like the bald eagle, the golden eagle is federally protected
under the Bald and Golden Eagle Protection Act, the Migratory
Bird Treaty Act and the Lacey Act. The golden eagle generally
prefers open country on its breeding range, but on migration
and during winter it favors the Appalachian’s forest ridges and
small openings along those ridges.
Adults and immatures have rich, dark-brown body plumage,
with gold-tipped feathers on the back of the head and neck.
The golden eagle is in a subfamily of “booted” eagles and its
legs are feathered to the toes. Adults resemble immature bald
eagles, but goldens are darker with fewer splotches of white.
Immatures have white wing patches and, for their first several
years, a broad, white band at the base of the tail. In flight the
eagle’s tail protrudes noticeably more than its small-looking
head protrudes. It also holds its wings in a slight “V” as
compared to the bald eagle’s flat plane, the so-called “flying
plank” of hawk watches.
Golden eagles are shaped like buteo hawks, with long,
rounded wings. They flap less and soar more than bald eagles.
Body length is 28 to 40 inches; wingspan is 6 to more than
7 feet, and standing height is about 2 feet. Their calls are a
series of rapid, sharp chirps or yelps, although they are most
often silent. Neither eagle calls as much as the more common
red-tailed hawk.
A golden eagle’s prey includes small
rodents, hares, rabbits, birds, reptiles and
fish. They also eat carrion and are capable
of killing large animals. Golden eagles crush
prey in their sharp talons, and use their
large, hooked beaks to rip it apart for
eating. In Pennsylvania, golden
eagles are regular migrants
in mid-October through early
December. Northbound migrations
occur in late winter and spring
with most sightings at hawk-watch
sites in March and April.
Golden eagles do not breed in
Pennsylvania. Some occasionally
winter here in rugged, remote forest
terrain, remaining out of site most
of the time. Most golden eagles
breed across central Canada, in the
western United States, Alaska and
mountainous parts of Mexico.
Breeding habits are similar to those of
bald eagles, except golden eagles often
locate their nests on cliffs. After fledging,
young remain in the nest area during summer, then wander
away from the site with their parents. They do not breed until
5 years of age.
A recent four-year survey (2006 to 2009) conducted by the
U.S. Fish and Wildlife Service suggests there may be 30,000
golden eagles across the United States. The eastern golden
eagle population is believed to be fewer than 2,000. The
golden eagle is not on the federal threatened or endangered
list, but has disappeared from most of the northeastern states.
Osprey
The osprey, Pandion haliaetus, is a large, eagle-like hawk
found throughout North America and in the Eastern
Hemisphere. It inhabits seacoasts and the areas near large
rivers and lakes. In Pennsylvania, it shows up along the major
rivers and their tributaries and around lakes, ponds, reservoirs
golden eagle
More Wildlife Notes are available from the Pennsylvania Game Commission, Bureau of Informaon
and Educaon, 2001 Elmerton Ave., Harrisburg, PA 17110-9797. www.pgc.pa.gov
and wetlands. The osprey prefers shallow water and requires
an abundant supply of fish within a reasonable distance
from its nest. Nests are usually nearby food sources, but
occasionally up to about 12 miles away. Ospreys are not as
likely as bald eagles to nest near flowing fresh water. Ospreys
also are more likely to nest in clusters at a lake or reservoir,
and usually on an artificial structure.
Osprey plumage is dark brown above and white below. Adults
and juveniles are colored similarly except juveniles show
buffy-white spots on their backs, a buffy shading on their
necks and chests and reddish-orange eyes. Adults have yellow
eyes. The osprey’s head is largely white, with a black patch
across each cheek. A conspicuous crook to the wings, creating
a characteristic “M” shape, and black “wrist” marks are good field
identifiers.
Except when migrating, ospreys flap more than they sail.
Wingbeats are slow and deep. Ospreys hover 50 to 150 feet
in the air and then plunge to the water for their fish prey,
sometimes going all the way under.
Ospreys are 21 to 24 inches from bill to tail. Their wings span
4 ½ to 6 feet. They stand about 1 ½ feet tall. Ospreys are quite
vocal and use several different calls to communicate with one
another. Their call is a series of loud whistles, cheep, cheep,
etc.
Ospreys typically migrate south in winter and return to
Pennsylvania in late March and early April to nest. They can
be seen migrating south along the mountain ridges in August,
September and October, with peak migration occurring
around the middle of September. During fall, many migrating
ospreys are also observed along Pennsylvania’s rivers. Ospreys
migrate to southern wintering grounds along the Gulf Coast
and in southern Florida south through Central America and
South America.
Like eagles, ospreys build bulky nests of sticks and twigs, lined
with inner bark, sod or grasses. Sometimes they add debris
(rope, fishnet fragments, cans, seashells, etc.). Nests are in
living or dead trees, on the ground, or on manmade structures
– cell towers, utility poles, fishing shacks, billboards, channel
buoys, light standards, chimneys and platform-topped poles or
towers erected specifically for osprey nesting. In Pennsylvania,
most known osprey nests are on manmade structures. Since
ospreys add to nests year after year, the nests can become
huge and conspicuous.
The nests usually include three eggs, sometimes two and
rarely four. Eggs are 2⅜ by 1¾ inches, and white or pinkish-
white with brown spots and blotches. The female incubates 36
to 42 days, and young leave the nest when they are 51 to 59
days old.
Dr. Larry Rymon of East Stroudsburg University in 1980 began
reintroducing ospreys to the state’s northeastern counties.
The first Pennsylvania-hacked osprey returned in 1983, and
two years later the state documented its first nesting pair
since 1910. An osprey has strong ties to the area where
it was hatched, and usually returns in the same area to
breed. Between 1980 and 1996, 265 young ospreys were
released into
Pennsylvania at
three different
locations: the
Poconos in
northeastern
Pennsylvania,
the Tioga County
reservoirs in
northcentral
Pennsylvania
and Moraine
State Park
in western
Pennsylvania.
These nestling
birds were
obtained from
the Chesapeake
Bay, which
has the
largest nesting
population of
ospreys in the world. A total of five reintroduction projects
between 1980 and 2007 helped fuel the osprey’s recovery
in Pennsylvania. The recent Second Breeding Bird Atlas
(2004-08) documents the osprey’s recovery with confirmed
nests reported in at least 90 atlas blocks, a tenfold increase
compared to the nine blocks confirming nests during the first
atlas period (1984-89). Most recently, osprey nest surveys
in 2010 reported 115 osprey nests in 21 counties with more
found since that year. The osprey is a state threatened species
and protected under the Game and Wildlife Code. Although not
listed at the federal level, all migratory birds are protected under
the Migratory Bird Treaty Act.
Raptor Reproducon
Reproductive failure is a problem for bald eagles and
ospreys. Much of the problem stems from man’s use of now-
banned toxic chemicals. DDT, dieldrin, and other chlorinated
hydrocarbons sprayed to kill insects, which contaminates
water and prey species in the food chain. Bald eagles eat a lot
of fish, and accumulate the chemicals in their bodies. Other
pollutants such as PCBs and heavy metals may also affect their
reproduction.
The chemicals cause birds to lay infertile or thin-shelled eggs,
which break under the weight of an incubating bird. Although
environmental regulations have banned the use of “hard”
pesticides, some chemicals remain in our natural food chains
because they do not break down rapidly and some harmful
chemicals banned in the United States continue to be used
in other parts of the world. Many birds are still exposed to
these toxins during migration and on wintering territories.
Monitoring bald eagle nests helps the agency follow the
recovery process and determine their population status. It
also allows biologists to detect environmental problems that
may be occurring both locally and statewide.
osprey
Pennsylvania Game Commission | www.pgc.pa.gov
Managing and protecting wildlife and their habitats while promoting hunting and trapping for current and future generations.
