The bald eagle (Haliaeetus leucocephalus) is a bird of prey found in North America. Its range includes most of Canada and Alaska, all of the contiguous United States, and northern Mexico. As a sea eagle, it belongs to the genus Haliaeetus and actually forms a species pair with the white-tailed eagle (Haliaeetus albicilla). It has two subspecies — the nominate species and H. l. washingtoniensis.
Despite their name, bald eagles are not actually bald, but have feathers that are mainly brown with a white head and tail. The common name bald eagle derives from an older meaning of the word, “white headed”.
The bald eagle is the national symbol of the United States. In the late 20th century, these eagles were almost extinct, but populations have since recovered. It is now listed as Least Concern by the IUCN Red List.
Bald Eagle Characteristics
Bald eagles are very large birds with a body length of between 70 to 102 cm (28 to 40 in). They weigh 3 and 6.3 kg (6.6 and 13.9 lb), although females are about 25% larger than males. The bald eagle’s wingspan is between 1.8 and 2.3 m (5 ft 11 in and 7 ft 7 in). The size of the bald eagle varies on its location, with the species increasing in size further away from the equator and the tropics.
The plumage of these eagles is evenly dark brown with a white head and tail, and both males and females look the same aside from their size difference. Their beak, feet and irises are bright yellow, and their beak is large and hooked. They have no feathers on their legs or feet, and they have short and powerful toes with talons. The highly developed talon of the hind toe is used to pierce the vital areas of prey while it is held immobile by the front toes.
Bald Eagle Lifespan
The bald eagle has a lifespan of anywhere between 15 and 30 years. However, they can live for even longer in captivity. Bald eagle eggs and juvenile bald eagles do not have a very high survival rate, but adult birds tend to have a 90% annual survival rate.
Bald Eagle Diet
Bald eagles are opportunistic carnivores and therefore eat a wide variety of prey. More than 400 species are known to be included in the bald eagle’s diet, but their diet mostly consists of fish, such as rainbow trout, American eels, gizzard shads, white catfish, kokanee salmon, rock greenlings, Pacific cod, atka mackerel, large mouth bass and chum salmon. However, they’ll also eat adult water birds, their nestlings and their eggs including common murres, great blue herons, snow geese, Ross geese, tundra swans, northern fulmars, auklets, American coots and common loons.
The species mainly target prey which is much smaller than themselves, with most live fish caught weighing 1 to 3 kg (2.2 to 6.6 lb) and most waterbirds preyed weighing 0.2 to 2.7 kg (0.44 to 5.95 lb).
In the winter, bald eagles often eat small mammals and carrion, such as ground squirrels, rabbits, hares, raccoons, beavers, montane voles, Norway rats, sea otter pups, elk, moose, deer fawn, armadillos, skunk, caribou, bison, wolves and arctic foxes.
When hunting by a river for fish, the speed of a river flow can greatly impact their hunting success. These birds do not submerge themselves to obtain prey, but instead use their strong talons to remove fish near the water surface. When hunting ground animals, perch and observe before descending on their prey and lifting it from the ground with their talons. They are also known to pirate prey from other raptor species, such as ospreys.
Bald eagles do not forage for food when there are humans around. In case of food scarcity, bald eagles often gorge and store food in their crop for later digestion. They can also survive for several days without food.
Bald Eagle Behavior
Bald eagles are generally solitary birds, but may be seen in large groups of up to 400 individuals in areas where there is an abundance of food. Pairs of bald eagles also bond during the nesting season.
These North American birds spend most of their time resting — up to 91% of their day is spent resting! — and the rest of the time is spent hunting for food. They are usually less active in the winter or when there are strong winds or rain that could interfere with their hunting.
These eagles have very strong wings and are therefore very powerful fliers. They can reach speeds of 56 to 70 km/h (35 to 43 mph) when gliding and flapping, and about 48 km/h (30 mph) while carrying fish. They tend to soar using slow, heavy wing beats, which allow them to travel far distances. They can walk, too, but they are slightly awkward about it! They tend to rock their bodies as they move.
Southern birds are resident and remain on breeding territory all year round. However, northern birds are migratory, particularly if the open water within their range freezes during the winter, making it impossible to obtain food. They will then migrate to the south or to the coast. Migration generally takes place during the daytime, usually between the local hours of 8:00 am and 6:00 pm, when thermals are produced by the sun. Birds return to their nesting sites at varying times, as soon as weather allows.
Contrary to popular belief, bald eagles have relatively weak, high pitched, thin vocalizations, composed of chirps, whistles and harsh chatters. They tend to communicate more with wing displays rather than with vocalizations.
Bald Eagle Reproduction
Bald eagles are monogamous and are believed to mate for life. They do not migrate with their mate, but perform displays when they come together for the breeding season. The breeding season takes place in and around March depending on the season, which is early compared to most raptors that mate in April or May.
The bald eagle begins to build its nest in either January or February. When they are old enough to breed, they often return to the area where they were born. Bald eagle nests are composed of sticks and are the largest of any bird in North America. The nest is used repeatedly over many years and with new material added each year may eventually be as large as 4 m (13 ft) deep, 2.5 m (8.2 ft) across and weigh as much as 1 metric ton. Nests are usually built in large trees near water, but may occasionally be built on the ground if there are no trees.
These eagles typically produce 1 brood of 1 to 3 eggs per season and are generally incubated for about 35 days. Incubation takes place from mid-March to early May. The eggs are round to oval and are generally whitish and range from 58 to 85 mm (2.3 to 3.3 in) long and 47 to 63 mm (1.9 to 2.5 in) wide.
Both the male and female take turns incubating the eggs, but the female does most of the sitting. The parent not incubating will hunt for food or look for nesting material during this stage. During the nestling period, young are fed 4 to 5 times per day. For the first two to three weeks of the nestling period, at least one adult is at the nest almost 100% of the time. However, after five to six weeks, parents may leave and perch in a tree nearby.
Bald eagles are the largest semi-altricial birds in North America and weigh approximately 60 grams at hatching and may gain up to 180 grams per day. Immediately after hatching, bald eagles have dark eyes, with pink legs and skin and flesh colored talons, although their skin darkens to a bluish hue and their legs become yellow within the first 18 to 22 days of their life. Throughout their first year, they have dark brown bodies, eyes and beaks.
The baby bald eagles leave the nest when they are between 8 and 14 weeks old, although they may remain dependent until they are 18 weeks old. Before leaving the nest, the young eaglets pick up and manipulate sticks, play tug of war with each other, practice holding things in their talons, and stretch and flap their wings. Bald eagles reach sexual maturity at around 5 years old.
By the time they are two years old, the bald eagles’s eyes lighten, becoming grayish-brown, they develop a light colored superciliary line and their body becomes mottled white. During their 3rd year, their bills and eyes begin to turn yellow and the coloration of their head feathers lighten, although their body remains mottled. In their 4th year, their body becomes mostly dark and their head and tail become mostly white, with some beige around their eyes and crown and isolated dark spots on their tail. By the time they are five years old, they will have developed their adult plumage.
Bald Eagle Location and Habitat
Bald eagles are found throughout North America. They are native to Canada, the United States, portions of Mexico and several islands including Saint Pierre and Miquelon, but some of the mot densely populated areas are Florida, Alaska, the Pacific Northwest and near some rivers and lakes in the Midwest.
They are mostly found near large water sources, such as sea coasts, coastal estuaries and inland lakes and rivers, usually no more than 3 km from one of these areas. Their habitats can vary, but are mostly decided on based on prey availability. They will perch, nest and roost in tall, coniferous trees or hardwood trees, surrounded by smaller trees. The trees must have good visibility, be over 20 m (66 ft) tall, have an open structure, and be in close proximity to prey.
The bald eagle may also nest on the ground, on cliffs, on cellular phone towers, on electrical poles and in artificial nesting towers. They generally try to avoid areas where there will be a lot of human disturbance.
Bald Eagle Conservation Status
Bald eagles are currently listed as a species of least concern according to the IUCN Red List of Threatened Species due to their increasing population and large range. However, this wasn’t always the case.
The bald eagle population was negatively affected throughout the 1900s by hunting, habitat destruction and the use of pesticides and insecticides, such as DDT. The Bald Eagle Protection Act was put into effect in 1940, but their populations still continued to decline. Fortunately, after the ban of DDT in 1972, their population has increased dramatically, but they were still listed on the Endangered Species Act in 1978.
Their population has continued to grow since the ban in 1972, and the bald eagle was officially removed from the U.S. federal government’s endangered species list on July 12, 1995.
Bald eagles can be kept in captivity in the United States, but a permit is required to do so.
Bald Eagle Predators
Adult bald eagles have very few predators, which allows them to nest on the ground without much worry. Most non-human-related mortality involves nestlings or eggs. The eggs and young are often preyed upon by magpies, gulls, ravens, crows, black bears, raccoon, bobcats, wolverines and arctic foxes. A study found that immature bald eagles have a survival rate of 89% in rural habitats and 65 to 72% in suburban habitats.
Bald Eagle FAQs
Where does a bald eagle live?
Bald eagles are found across North America, particularly in areas close to large bodies of water, such as estuaries, large lakes, reservoirs, rivers, and some seacoasts. Some of these birds migrate to warmer areas during the winter when water sources near to them freeze over.
They usually nest, rest and perch in tall trees where they have good views of the area around them for spotting prey.
How big is a bald eagle?
A bald eagle is a very big bird with a body length of between 70 to 102 cm (28 to 40 in) and a wingspan between 1.8 and 2.3 m (5 ft 11 in and 7 ft 7 in)! Males are usually larger than females.
How much does a bald eagle weigh?
Bald eagles weigh between 3 and 6.3 kg (6.6 and 13.9 lb)! This allows them to hunt very large prey, including fish that can weigh up to 3kg!
How tall is a bald eagle?
Adult males are around 90 cm (36 inches) long and have a wingspan of 2 metres (6.6 feet). Females, which grow somewhat larger than males, may reach 108 cm (43 inches) in length and have a wingspan of 2.5 metres (8 feet).
What does a bald eagle eat?
Bald eagles are opportunistic feeders. They are carnivores and have a huge range in their diet, with more than 400 species of animal included in their diet! Their diet mostly consists of fish, but they’ll also eat waterfowl and small mammals. They use their very strong talons to pick up their food and pierce vital organs, killing the prey before they eat it. These birds also pirate prey off other birds sometimes!
How long does a bald eagle live for?
A bald eagle usually lives for between 15 and 30 years in the wild, but may live even longer in captivity.