BALD EAGLE

Class: AVES

Order: ACCIPITRIFORMES

Family: ACCIPITRIDAE

Genus: HALIAEETUS

Species: LEUCOCEPHALUS

This species of bird of prey belongs to the family Accipitridae, in which it belongs to the genus Haliaeetus, containing birds known commonly as ‘sea-eagles’. It is unique for its genus in that, however, where all other species of sea-eagle are to be found in Europe, Asia and Africa, the Bald Eagle is the only member of the genus to be found in the Americas. The Bald Eagle, the national animal of the United States, encompasses a range which is found as far north as the northernmost areas of Canada and Alaska, and as far south as Northern Mexico. The species can be found, on occasion, in all the United States with the exception of Hawai’i. However, its territory is not defined by human-designated states – as it is a permanent resident in rather indiscriminate areas – as far west as the states of Oregon and Washington, and as far east as Florida. Its status of residency may be linked to the presence of coniferous forest in such areas, where in areas of prairie which lack such trees, it does not assume residency.

Two sub-species of the bald eagle are currently recognized. The Northern Bald Eagle, H. l. washingtonensis, is found in northern areas of the North American continent – and the Southern Bald Eagle, H. l. leucocephalus, is found in more southern areas. It is smaller than its northern relative – a display of Bergman and Allen’s rule. The fossil record indicates that the bald eagle has existed for at least 1 million years, though it is probably older than this. The species most closely related to the bald eagle is the white-tailed eagle, which is found in Eurasia. The exact specifics behind why the bird was named ‘bald’ remain unclear – but does not refer to the physical state of the bird’s head, which is feathered in a roughly equal degree as the other sea eagles. Some authors believe it to be derived from Old English ‘balde’, which means ‘white’ – other authors believe it to derive from ‘piebald’ – which refers to animals, especially domestic breeds, which are irregularly black and white in colouration. Others suggest that it refers to the bird’s resemblance to an older person going through early stages of baldness, as their hair begins to whiten.

Bald eagles are, on average, 80 or so centimetres in body length, and weigh up to 6 kilogrammes, though many are lighter than that. They have a wingspan of about 206 centimetres, at a median, though this can be up to 244 centimetres. It is an unmistakable bird on the North American continent in its adult form – it has a distinctive white head and white tail feathers, a large yellow beak as well as yellow talons, which have three front claws and a back-claw – with much of the body being covered with dark brown or black feathers. As is the case with most raptors, female bald eagles are larger than are male bald eagles. The colour of the bald eagle, however, is not consistent with age. Young bald eagles are a brown colour, looking more akin to a golden eagle [which also occurs on the North American continent], though as they age they start becoming mottled with white feathers. The eye is typically yellow. The underside of the wings of the adult bald eagle, unlike other raptors, is not significantly different in colouration to the above side of the wings. When in flight, bald eagles have their wings fully out-stretched as they soar – so that the bord almost forms the letter ‘T' from below. When preparing to land, or to catch prey, the eagle contorts so that its legs are stretched in front of its bent head – so that from the front it resembles the shape of the letter ‘Y’. Like other eagles, the soaring ability of the bald eagle is efficient to such a degree that flapping is rare.

Bald Eagles are most often found in areas which are close to water – such as coastlines, lakes – and even coniferous swamps. Even so, it is an adaptable bird – inhabiting simultaneously the tundra of Canada and Alaska as well as the deserts of Mexico. In addition to being adaptable in habitat, bald eagle diets are also highly adaptable, with the birds being capable of eating a wide variety of foodstuffs. The species mainly eats fish, which it eats often in the summertime – but also is capable of eating small or medium-sized birds such as waterfowl, small mammals such as rabbits or muskrats, invertebrates, reptiles, and also garbage. To achieve their normal calory intake of, at a median, 500 calories per day, adult bald eagles may eat, on a median, 13% of their body weight. The breeding season of the bald eagle is dependent on the sub-species – the Northern Bald Eagles seem to breed predominantly from April to August – whereas the Southern Bald Eagles seem to breed predominantly from October to April. Bald Eagles seem to prefer their nests being placed in coniferous trees – though in some cases it also can be placed on the ground. When complete, the nest can be very large – about 2.5 metres in diameter, and about 4 metres deep. Both of the sexes contribute to construction of the large nest, though females predominantly do the placement of foundation of materials. Bald Eagles may return to the same nest for many years. On occasion, the nests can be even larger – the largest North American bird nest recorded to date was that of a bald eagle nest – found in Florida, the nest was almost 3 metres in diameter, and 6 metres deep. The nest is thought to have weighed more than 2000 kilogrammes. This nest may no longer hold the record for the largest nest of all, however – the Australian malleefowl builds nests which can be 4 metres high and 10 metres in diameter.

Bald eagles are rather social outside of the mating season, congregating at communal roosts. However, they are not co-operative in activities such as hunting or feeding – where rivalry often occurs between bald eagles and also other predators. In the mating season, however, they are very territorial – fending off rivals to their mates and offspring. The species is monogamous – it mates for life, except in the case either mate dies or does not return. Bald eagles only breed once a year. Bald eagle eggs are incubated for about 25 days before hatching, and are speckled in colouration. Bald eagles seem to prioritise maximising egg number – in seasons of food abundance, as many as three eggs will be laid – but in other times, only two or just one will be laid. In a typical family structure, the male bald eagle provides food for the brooding female and their chicks. Though later in the chicks’ life, both parents bring food to the nest, with the female seemingly bringing more food. The female spends much time tending to the young in the first three or so weeks – though after this, the parents seem to leave the nest unattended for longer. After about 80 days or so, bald eagle chicks begin to fly. In increased maturity, bald eagle chicks also become increasingly violent – with killing of siblings common within the species. Typically, the first-hatched chick is the one who will kill any chicks which hatch afterward. They become sexually mature at 5 years of age typically – though in some populations only 8% or so reach breeding age. The oldest captive bald eagle on record was about 47 years old – and the oldest wild bald eagle on record was a New York bird which died at age 38. However, many wild birds die earlier than this, with a typical lifespan being one of about 20 years.

Before its adoption as the emblem of the United States, the bald eagle was a creature of high importance to the native peoples of North America. Eagles were common in arts of many, though not necessarily all, Native Americans, and in the many Native American societies, the receiving of an eagle’s feather was the highest honour of all. Many Native Americans considered the Bald Eagle as being intimately connected to The Creator, who chose the Eagle as the leader, and as a messenger. These Native Americans saw how the eagle soared higher and saw better than any other bird in the area – in the religion of many Native Americans, they saw this as how it was closer to The Creator than any other creation. The Creator is said to take notice of when an eagle’s feather is adorned by a person, honoring The Creator like no other way. Amongst such Native Americans, the eagle’s feather is to be treated with the highest level of care and respect – it should be stored safely in the home, and never be tarnished or damaged. Yet, the bald eagle was probably not the most coveted of all – not the degree as was that of the golden eagle. In the 18th century, about a century after the colonisation of North America by the Europeans, the bald eagle was printed onto a Massachusetts copper cent coin – the first coin printed to feature the animal. In 1783, three years before, the topic of the national emblem was discussed amongst people of high leadership. It wouldn’t be until six years later, in 1789, that the Bald Eagle would be adopted, as a symbol of courage and freedom. Not all proponents were supportive, however. Benjamin Franklin is known to have written -

‘I wish the bald eagle had not been chosen as the representative of our country; he is a bird of bad moral character; like those among men who live by sharping and robbing, he is generally poor, and often very lousy. The turkey is a much more respectable bird and withal a true, original native of America.’

Franklin’s sentiments carried little weight, however – and the bald eagle was quickly adopted as the emblem of the then 13 colonies that made up the United States. In the present day, the bald eagle appears on the Seal of the United States as well as the country’s Coat of Arms, as it has for over 200 years. President John F. Kennedy also thought highly of the Bald Eagle, and is known to have written to the Audubon Society –

‘The Founding Fathers made an appropriate choice when they selected the bald eagle as the emblem of the nation. The fierce beauty and proud independence of this great bird aptly symbolizes the strength and freedom of America. But as latter-day citizens we shall fail our trust if we permit the eagle to disappear.’

The Bald Eagle has since a potent symbol of the United States of America, symbolising to its citizens patriotism, strength, and liberty.

Bald eagles have been hunted on occasion by Native Americans, though it is not believed that Native Americans caused significant decline within the species. When European colonists started to farm, they perceived bald eagles as a threat to livestock, and European hunters felt that bald eagles competed with them for game animals or fish. In the year 1917, the state of Alaska introduced a bounty system for the bald eagle, which resulted in at least 120,000 eagles being killed – and probably many more left unrecorded. The Bounty was repealed in 1953, but an already-damaged population would soon experience further dramatic decline. The most dramatic decline of the bald eagle, however, came after the Second World War when pesticides were used on agricultural crops. The pesticides would go on to enter waterways and began to accumulate within fish, the main food-source of bald eagles. DDT, known also as Dichlorodiphenyltrichloroethane, became commonly-accumulated in bald eagles – whilst not toxic to adult birds, it made the eggs laid have thinner and more permeable shells, which were unable to support the weight of the parents. In the contiguous 48 states, by the year 1963, only some 417 pairs were known to remain – the species threatened with extinction.

In 1967, the Southern Bald Eagle was listed federally as an Endangered Species. The Endangered Species Act of 1973 enlisted further protection to certain Bald Eagle populations, with other populations also gaining legal protection in 1978. In the year 1972, DDT would become banned as use of a pesticide. This would correlate with the increase once again in Bald Eagle populations. In 1995, it was federally moved from ‘endangered’ to ‘threatened’ status. In 2007, when it was estimated there were almost 10,000 nesting pairs within the contiguous 48, it was removed from the Endangered Species Act. As of 2021, it was estimated there are some 316,000 or so bald eagles within the contiguous 48 states. The bald eagle, thus, leads one of the best-known, and probably successful, stories of conservation success of all time. Today, the US Fish and Wildlife Service continues to work with federal agencies, non-governmental organisations, and native tribes to secure the species’ existence – and the bald eagle still enjoys federal protection under various acts which prevent the killing or trading of bald eagles, as well as preventing damage to their nests and eggs.

The Wenden Animal Encyclopaedia would like to thank especially:

The John F[itzgerald]. Kennedy Presidential Library.