Bald Eagle Facts
If you spend any time exploring the photographs here on DownhomeLife.com, you'll find a number of readers have submitted shots of bald eagles - many of them juveniles - that they've snapped in different parts of Newfoundland and Labrador. These photos inspired us to find out more about Haliaeetus leucocephalus (Haliaeetus denotes "sea eagle" and leucocephalus refers to its white head).
In some parts of Canada eagles prefer to nest in conifers, especially pines. Old-growth forests provide the most suitable nest sites, but where there are no trees, the birds nest on cliffs, rock pinnacles, or, in the northern tundra, the ground. Only a few eagles have been recorded nesting on human-made structures.
The timing of the breeding cycle depends on where the nest is located. Northern populations breed later and have a shorter breeding season. Egg laying is in April and May in Canada and Alaska, and from mid-November to mid-January in Florida.
The female usually lays two large dull white eggs, two to four days apart. During the 35 days of incubation when the eggs must be kept warm and protected from predators, one of the adults (usually the female) is on the nest almost all the time.
The eggs hatch two or three days apart. Covered in grey down at hatching, eaglets begin to sprout feathers at four or five weeks. The female typically broods the young, shielding them from rain, wind and sun - continuously at first and sporadically after the first month. The male carries most of the food to the nest during the first weeks; both adults do so after this.
Young eagles have enormous appetites and grow rapidly, increasing from about 90 g at hatching to an average of 4 kg (males) and 5.1 kg (females) in two months. After six or seven weeks the juveniles feed themselves and show considerable aggression toward the parents. Males can fly at about 78 days and females, a few days later.
Bald eagles disperse from breeding grounds in Newfoundland and Labrador between mid-October and the first week of November - later than the rest of Canada. The Gulf of St. Lawrence is an important stopover area for migrating eagles.
Travelling alone or in pairs, young bald eagles from the population that breeds in Florida during November and December wander north in the summer, sometimes as far as the East Coast provinces.
When they first leave the nest, bald eagles are not good at catching fish. They learn to hunt by first picking up dead fish along shorelines, and then progress to picking up dead fish floating in rivers and lakes. It may take months for an eagle to become reliable at catching live fish.
Bald eagles feed primarily on fish, aquatic birds and mammals, which it may take alive or find dead. When its staple foods are not available, these large birds of prey will eat almost anything that has food value and take food however they can - stealing it from other birds, scavenging on carrion (including road kills and dead salmon that have reached their spawning grounds), and hunting in flight.
To kill and handle prey, bald eagles have massive beaks, large talons and oversized feet equipped with small spikes, called spicules. They are unable to carry much more than four pounds in flight.
When hunting from the wing, eagles will travel at a mid-altitude of 17-34 m (50-100 ft) above the ground and will dive feet first to capture prey. A typical hunting sequence involves hunting over water until prey is spotted. The eagle will then dive feet first into the water, latch onto its prey with its talons and pull it out, then carry it to a perch, sandbar or nest to eat.
In a March 2004 interview with CBC Radio, Newfoundland and Labrador's executive director of science, Shane Mahoney, discussed how his research team had discovered that bald eagles in the province were preying on newborn caribou calves - perhaps as a result of a growing eagle population and increased competition for a dwindling food resource: fish.
Eagle bones are light because they are hollow. The bulk of their weight comes from the more than 7,000 strong and flexible feathers covering their body. The beak, talons and feathers are made of keratin.
Bald eagles see three or four times farther than people - an obvious advantage to a bird that hunts and scavenges. They probably hear about as well as humans do, but their senses of taste and smell are poorly developed.
Bald eagle populations have declined because of the loss of waterside habitat and nesting trees; intentional shooting by poachers; illegal trapping (mostly in the western United States); and contamination of food sources (especially by pesticides like DDT) with subsequent ill effects on health and reproduction.
The bald eagle was declared an endangered species in the U.S. in 1973. However, due to the banning of DDT, reintroduction programs and habitat protection measures, it was reclassified from endangered to threatened in the lower 48 states in 1996.
Canadian bald eagle populations are generally stable or increasing slightly, although the situation varies by region. Populations in coastal British Columbia, the boreal forest and the Atlantic provinces are doing well. If suitable habitat remains available and human disturbance is kept to a minimum, we should be able to enjoy this magnificent soaring bird for some time to come.