Author: Noelle M. Brooks

Bald eagles are the largest semi-altricial birds in Norther America, weighing 60 grams at hatching and gaining up to 180 grams per day.

Although bald eagles are often solitary, they pair bond during the nesting season and may congregate in areas with ample prey or roost communally in groups of up to 400 individuals.

Bald eagles have been the national symbol of the United States since 1782 and draw bird watchers and other nature enthusiasts with their charisma.

Because bald eagles reuse and build upon their nests each year, they become massive in size, weighing up to 2 tons.

Bald eagles forage, hunt, and pirate for their food, and the speed of a river's flow can greatly impact and eagle's hunting success.

Although fully grown bald eagles are not often subject to predation, their eggs and young can be preyed upon by magpies, gulls, ravens, crows, bears, raccoons, bobcats, wolverines, and arctic foxes.

About 1-3 months prior to egg-laying, male and female bald eagles will construct nests together, though the dates vary regionally, nesting earliest in the East and latest in the West.

Bald eagles perform flight displays with their mates, plummeting towards the ground with their feet clasped and letting go just before impact.

If lost, a bald eagle's flight feathers may take 2-3 years to regrow.

Bald eagles are fully migratory and most populations of bald eagles, specifically those in northern regions, migrate to southern, milder climates annually.

Bald eagles have a low fecundity and typically produce one brood of 1-3 round, white eggs per season, but may have replacement clutches if needed.

Bald eagles are diurnal and are less active during the winter, when winds are especially high, or when there's precipitation.

Bald eagles begin breeding when they are 5 years old and have a monogamous mating system, mating for life.

With large, forward facing eyes, bald eagles likely have very good binocular vision.

Bald eagle breeding varies geographically as populations located further north tend to have shorter breeding seasons and more synchronous nesting periods and produce larger eggs.

While bald eagles choose habitats with plenty of prey and tall trees, they will inhabit areas further from foraging grounds in order to avoid human interaction as human activity decreases their feeding by 35%.

Bald eagles are opportunistic foragers and have a wide, varied diet feeding on fish; adult water birds, their nestlings, and their eggs; carrion; small mammals; and even human refuse.

Bald eagles have sexually monomorphic plumage coloration, although females generally have a somewhat larger body size.

There are two recognized subspecies of bald eagle with the larger subspecies, H. l. alascanus, being larger than the southern, nominate subspecies, H. l. leucocephalus.

Bald eagles are found throughout North America and prefer areas near large bodies of water such as sea coasts, coastal estuaries, and inland lakes and rivers, typically residing within 3 km. of water.

The bald eagle gets its common and scientific names from the distinctive appearance of the adult's head as mature coloration is reached in the eagle's fifth year.