SPECIES

Bald Eagle Haliaeetus leucocephalus Scientific name definitions

David A. Buehler
Version: 2.0 — Published October 7, 2022

Photos from this Account

Adult

Very large raptor with long, broad wings. Dark brown body contrasts with its white head and tail.

Juvenile

Juveniles have a brown body with brown and white mottled wings. The tail is also mottled with a dark band at the tip.

Juvenile

Amount of white in the wings is variable on juveniles.

Second year
Adult

When perched appears very large, with brown body and contrasting white head and bright yellow bill.

Adult

Will hunt for fish when near water.

Fourth year

Fourth year birds look like adults with some brown feathers on the otherwise white head.

Second year

Second year birds are strongly mottled brown and white.

Juvenile

The amount of white feathering can be highly variable on juveniles and second year birds.

Second year

Second year birds have a mostly white belly, with some brown mottling, a brown chest, and a broad brown mask on the face.

Adult and immature

Will form groups during the nonbreeding season, when different age classes can be seen together.

Adult

Constructs enormous stick nests, usually in large trees.

Possible confusion species: Juvenile Golden Eagle (Aquila chrysaetos)(below) and immature Bald Eagle (above).
Possible confusion species: Golden Eagle (Aquila chrysaetos) (left) and immature Bald Eagle (right).

Immature Golden Eagle

First down.
Second down.
Second down.
Juvenile lateral view (subspecies leucocephalus).

Fresh juveniles are primarily brown with some white-tipped upperwing coverts and a dark bill.

Juvenile ventral view (subspecies washingtoniensis).

In flight, juveniles have uniformly juvenile flight feathers and underwing coverts, primarily dark but with a variable amount of white mottling.

Juvenile dorsal view (subspecies washingtoniensis).
Formative plumage (subspecies leucocephalus).

By June some body feathers can be replaced (including scapulars and back feathers here), indicating Formative Plumage. Some Bald Eagles can lack a Preformative Molt and remain in Juvenile Plumage until the Second Preabsic Molt commences with inner primaries.

Formative plumage dorsal view  (subspecies washingtoniensis).
Second basic resting (subspecies leucocephalus).

Second Basic Plumage usually becomes whiter than Juvenile Plumage, through a combination of replacement with whiter second basic feathers and bleaching of remaining juvenile feathers.

Second basic ventral view (subspecies leucocephalus).
Second basic dorsal view (subspecies washingtoniensis).
Second basic ventral view (subspecies leucocephalus).

This individual has replaced more primaires and secondaries than the preceding, with the outer for primaries (p7-p10), s3-s4, and and s7-s11 retained as juvenile; not that the juvenile secondaries are longer than the replaced second basic secondaries. It is possible that this individual is in delayed Third Basic Plumage as opposed to advanced Second Basic Plumage although coloration of body feathering suggests the former,

Third basic resting (subspecies washingtoniensis).

This individual retains dark coloration over much of the body, but the retained, very worn, juvenile s4 and s9 among two generations of basic feathers (second and third) indicate Third Basic Plumage.

Third basic dorsal view (subspecies washingtoniensis).

The dark head with only a bit of white and two generations among the primaries (p5 may be second basic and the remainder third basic) indicate advanced Third Basic Plumage.

Third basic ventral view (subspecies washingtoniensis).
Fourth or fifth basic resting lateral view (subspecies leucocephalus).
Fourth or fifth basic ventral view (subspecies leucocephalus).
Fourth or fifth basic dorsal view (subspecies washingtoniensis).
Fourth or fifth basic ventral view (subspecies washingtoniensis).

It is difficult to know if this bird is in its fourth or fifth molt cycle. There are three sets among the primaries of the right wing, p1, p2-p6, and p7-p10, which may be more consistently found on a bird in Fourth Basic Plumage.

Definitive basic resting (subspecies leucocephalus).

Note the all-white head and tail and uniform basic upperpart feathers. Younger age (plumage) classes often display mixed generations or wear patterns to upperpart feathers due to incomplete or protracted molts.

Definitive Basic dorsal view (subspecies leucocephalus).
Leucistic individual.
Leucistic individual.
Bill and cere.

Third cycle birds have yellow bills with a dark line along the top and a mostly yellow cere.

Eye.

Iris is brown until second or third cycle.

Feet and legs.

Both juveniles and adults yellow legs and feet with black talons.

Definitive basic plumage resting (subspecies washingtoniensis).
Definitive basic plumage lateral view (subspecies washingtoniensis).
Formative plumage lateral view (subspecies washingtoniensis).
Second basic plumage resting (subspecies washingtoniensis).
Breeding habitat; Alaska, United States.
Breeding habitat; Colorado, United States.
Breeding habitat; Alaska, United States.
Flying over urban area.
Chasing Osprey with fish.
Attacking heron.

They will steal food from herons that are better at capturing live fish but have limited defense ability.

Hunting Northern Pintail.
Consuming a Common Merganser.
Bald Eagle in river after killing a Goldeneye (Bucephala sp.).
Bald Eagle capturing Great Blue Heron (Ardea herodias) prey.
Bald Eagle with Great Blue Heron (Ardea herodias) nestling.
Feeding on raccoon.
Feeding on seal.
Feeding on groundhog (Marmota monax).
Feeding on ground squirrel (Otospermophilus beecheyi).
Feeding from dumpster.
Bald Eagle with Common Murre (Uria alga) prey, being mobbed by gulls.
Bald Eagle with fish prey, being mobbed by Red-winged Blackbird (Agelaius phoeniceus).
Bald Eagle capturing a Canada Goose (Branta canadensis).
Bald Eagle with Glaucous-winged Gull (Larus glaucescens) nestling being chased by adults.
Bald Eagle with waterfowl prey.
Bald Eagle with Ring-billed Gull (Larus delawarensis) prey.
Bald Eagle with deer carcass.
Consuming a rabbit.
Feeding on crab.
Bald Eagle with aquatic salamander prey.
Drinking.

They derive most of their water from their food. Drinking only occurs while bathing.

Drinking.
Aggression between an adult and immature.

Agonistic behavior is common between territorial birds and non breeding birds in their territory.

Two Bald Eagles engaging in an aerial confrontation.
A physical confrontation that began in the air and continued in water.
A pair vocalizing.
Aerial mating display.
Copulation.
Large feeding group.
Mobbing.
Peregrine falcon attacking eagle.
Short-eared Owl (Asio flammeus) mobbing Bald Eagle.
Eagle and other birds at feeding sight.
Nest in coniferous tree.
Nest on human made structure.
Nest in deciduous tree.
Ground nest.
Nest on anthropogenic structure.
Adult with nesting material.
Adult with nesting material.
Nest composed of sticks and branches.
Nestlings with parent.
Young juvenile in nest.
Eagle flying by cars.

Collisions with vehicle represents a significant percentage of mortality.


Macaulay Library Photos for Bald Eagle

Top-rated photos submitted to the Macaulay Library via eBird. Note: Our content editors have not confirmed the species identification for these photos.

Recommended Citation

Buehler, D. A. (2022). Bald Eagle (Haliaeetus leucocephalus), version 2.0. In Birds of the World (P. G. Rodewald and S. G. Mlodinow, Editors). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bow.baleag.02