Many bald eagle populations use geographic landmarks for navigation, making the Mississippi River a major migratory corridor.
Contrary to popular belief, bald eagles have relatively weak, high-pitched, thin vocalizations composted of chirps, whistles, and harsh chatters and produce 3 main types of calls.
As a top predator, bald eagles impact all members of their community and have been causing a population decline in common murres.
Immature bald eagles are often confused with golden eagles due to their dark coloration, but bald eagles have longer heads, shorter tails, and blotchy white coloration on their underwing coverts, axillaries, and tails.
Due to hunting, habitat destruction, and insecticides, bald eagles were once an endangered species, but thanks to The Bald Eagle Protection Act and other conservation efforts, they’re now considered “Least Concern” on the IUCN Red List.
Bald eagle home range sizes may vary as populations in Oregon and Washington have larger ranges that those in Alaska, but they do not oscillate between breeding and non-breeding seasons.
Although both bald eagle parents care for the offspring, the female broods the eggs more frequently and is present 40% more than the male while the male provides most of the food during the first two weeks post-hatching.
While migrating, bald eagles generally soar and congregate in areas with food abundances, specifically in areas below the freeze line with open water for hunting.
Bald eagle eggs are generally only exposed for less than a minute at a time when the parents change positions or turn the eggs.
Although bald eagles do not have an adept sense of smell, they do avoid food items that taste spoiled.
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.