Species: Bald Eagle (Haliaeetus leucocephalus)
Favourite food: Fish
How he got his name: We named him after the salmon species but spelled it like the hockey equipment manufacturer for his Canadian heritage
Natural behaviours: Displaying his majestic flight
Favourite thing to do at the Earth Rangers Centre: Playing in his pool and sunbathing
Here’s what Animal Trainer Laura has to say about Koho
Koho is one of our most impressive ambassadors and definitely a real favourite for anyone that has the opportunity to meet him. Something most people might not expect from such a powerful animal is how completely trusting and affectionate he is with his trainers
- Bald eagles aren’t really bald! Their head is actually covered in white feathers. When they are young Bald eagles have brown feathers on their head. Between the ages of five and seven these feathers will have turned white.
- They can fly at speeds of over 50 km per hour and dive at speeds between 120 – 160 km per hour!
- When hunting fish, they’ll swoop down, grab one out of the water with their talons and fly away. However, they’ll only be able to carry it if it weighs less than half their body weight (about five pounds or less). Eagles have been known to drown trying to lift a fish that was too heavy.
- They make the largest nest of any bird in North America.
- Conservation status: Bald eagles were endangered because of hunting and pesticides like DDT, but thanks to conservation efforts their populations were upgraded to least concern in 2007
The national bird of the United States, the Bald eagle is one of the most well-known raptors in the world. Males and females look alike, but females are much larger. Males average nine pounds; females average 13 pounds. Males also have shorter wingspans. An adult male Bald eagle can have a wingspan up to seven feet, while females can have wingspans of nearly eight feet. Their feet are yellow and powerful, with sharp talons (claws) for grasping their prey. The hallux, or talon at the back of their feet, is the longest and points in the opposite direction of the other three talons. It is used to pierce into their prey while the prey is held by the other talons. Their large beaks are hooked for tearing meat. Like all eagles, Bald eagles have exceptional eyesight, which is used to locate their prey. Bald eagles are larger further away from the equator, a trait called “Bergmann’s Rule”. Sometimes, young Bald eagles are mistaken for Golden eagles. Bald eagles do not develop their iconic white patches until they are between five and seven; until then they are mostly brown, just like Golden eagles. The best way to tell these two species apart is by looking at their legs—Golden eagles have feathers all the way down to their feet, but Bald eagles do not. Golden eagles are also identified by the dark terminal band on their tail. Bald eagles do not have this band. While they might look scary, their voice is anything but. Their calls range from chirping whistles to shrill squeals. Often, when eagles are portrayed in movies, a different birds’ call is used instead of the eagles, usually the piercing cry of a Red-tailed hawk!
Native to North America, the Bald eagle can be found throughout the continent, with most of their population located in the North-western United States, Alaska and across Canada. Bald eagles prefer living in forested habitats near large water bodies, where they can catch plenty of fish and are isolated from humans. Bald eagles that nest inland tend to spend the winter near the coast, and birds that nest far up north will travel further south to avoid the extreme cold. Eagles that nest in areas where it doesn’t freeze during the winter will tend to remain in that area year round. Unlike some birds of prey, Bald eagles are not especially comfortable living near people. They are not found in urban centres like some falcons and hawks, and will usually only come near developed areas if there are fish to be caught on landfill sites. Bald eagles have been known to hang around dams and fish processing plants to find easy meals.
As apex predators, Bald eagles have very few natural threats in the wild. Horned owls will sometimes predate on young eagles. They are very large and usually aren’t hunted by other birds or mammals. If a population of Bald eagles begins to decline, such declines may be related to human activities. Bald eagles live nomadically for the most part, meaning they wander about with no real home territory. Young eagles will sometimes gather in large numbers around an area with lots of food, like when salmon are swimming upstream in rivers to spawn. At these times, there may be a high number of eagles in the area, but they will continue to live independently and will leave as quickly as they came once the food is gone.
Bald eagles eat mostly fish, which they can pluck from the water as they skim along the surface. If fish are not available, they will eat mammals like rabbits and muskrats, reptiles including lizards and snakes, or even carrion (animals that are already dead when they find them). Although they are capable hunters, Bald eagles steal prey from other animals. They are often seen chasing down smaller birds, like ospreys, to force them to drop their food. When the smaller bird is brave, the Bald eagle will use a more extreme tactic; physically fighting the bird to get its prey. Birds aren’t the only animals that eagles bully. They also go after mammals like sea otters and coyotes to get them away from their carcasses! Despite their ability to push other animals around, Bald eagles are themselves sometimes harassed and chased away by much smaller birds, including blackbirds and flycatchers. These songbirds team up and chase the eagles from nest sites by dive-bombing them in the air in large groups. This behaviour is called mobbing.
Bald eagles mate for life, but if a pair member dies the other bird will find a new mate. Bald eagles make the largest nests of any bird in North America. The same sites are reused by breeding pairs year after year, with new nesting material being added each season. Some of these nests, called aeries, are supported by massive trees and can become as large as four metres deep, 2.5 metres wide, and weigh 1000 kilograms! Nests are generally made of materials like branches and are stuffed with grass and moss. In areas where large enough trees can’t be found, Bald eagles will make nests on the ground using whatever material may be in the area. Females will lay up to three eggs, one at a time a few days apart. The eggs hatch after about six weeks—because the eggs are laid at different times, some hatch earlier than others. This staggered laying means some of the chicks will grow larger faster, and can lead to stiff competition in the nest for food between siblings. Bald eagles, like many other bird species including songbirds, are altricial, meaning eaglets cannot take care of themselves when they hatch and require care from their parents. Eaglets begin fledging after two months, and reach full adult size by the time they are three months old. It can take up to seven years before they grow their iconic white head and tail feathers. Life for a baby eagle can be tough—only 50% of eggs that hatch will actually grow into adults. Part of the reason for this is competition with their siblings for food. Young Bald eagles managing to survive to adulthood generally live to be over 20 years old in the wild!
- Least concern (IUCN, 2012), not at risk in Canada (COSEWIC 1984)
- In the past, Bald eagles faced threats from pesticide use and habitat loss, but conservation efforts have been incredibly successful!
Although currently considered a species of least concern, Bald eagles were once really close to extinction. In the early 1900s, Bald eagles were hunted by humans for their feathers and to keep them away from farms and fisheries. Later in the century, use of DDT, a pesticide developed during World War II, nearly wiped out the Bald eagle entirely. This chemical got into the water system and contaminated the fish that the Bald eagles ate. This ecological process is called “biomagnification”, meaning the chemicals increased in concentration up the food chain until they were hurting Bald eagles. DDT affected many bird species in the same way. The birds weren’t able to properly use calcium in their diet, which was an especially large problem for females during egg laying. With a shortage of calcium, the shells of the eggs were very brittle and thin, to the point where they would break if the mother tried to incubate them. As fewer and fewer Bald eagles hatched successfully, their populations dropped from 50,000 before the use of DDT to fewer than 800 breeding pairs in 1972, when, thankfully, this pesticide was banned. Since the banning of DDT, as well as the introduction of captive breeding programs, the Bald eagle has made a stunning recovery. Their numbers in the wild continue to increase to this day, and in June 2007 the Bald eagle was finally removed from the Endangered Species List. While there are still concerns about loss of habitat, the Bald eagle remains a spectacular example of the great things people can accomplish when they work together to protect biodiversity!
Cornell Lab of Ornithology, Bortolotti (1984). Physical development of nestling bald eagles with emphasis on the timing of growth events. Wilson Bulletin 96:524-542.