A bald eagle flies low over the water with a fish in its talons. (iStock photo)

It was nearly 50 years ago in Montana’s beautiful Glacier National Park. I still carry a vivid image of a magnificent bird gliding on afternoon thermals above an azure lake. After 15 years of regular sightings here in Maine, these birds still excite me every time.

The bald eagle, Haliaeetus leucocephalus, is part of the fish eagle family that includes the rare Steller’s sea eagle spotted in Maine last January. One of the largest birds in North America, an adult female is often 25% larger than her mate and may reach 3 feet in length, with powerful wings spanning 7 feet. In Alaska, a salmon diet allows some birds to exceed 14 pounds, making them a formidable predator. Bald eagles can fly with fawns or fish up to their own weight.

While juvenile eagles look like dusky, rumpled teenagers, when their plumage matures in the fifth year of life, adults are striking birds. Their bodies are predominantly dark brown, a sharp contrast with the white head, neck and tail feathers. The legs and beaks are yellow, and those piercing eyes are bright yellow. Throw in black talons 10 times more powerful than human hands, a wicked hooked beak, and this bird captures your attention!

We nearly eliminated our eagles, with just 20 breeding pairs in Maine by 1967, thanks to loss of habitat, pollution, unrestricted hunting, and DDT. In Alaska, more than 128,000 eagles were shot for a bounty of $2 to protect fox farms and salmon runs. The 1918 Migratory Bird Treaty and the 1940 Bald and Golden Eagle Protection Act signaled changing attitudes. In 1967, the bald eagle was designated an endangered species, and DDT was banned in 1972. The population is no longer endangered, with around 400,000 in North America and more than 700 breeding pairs in Maine.

Although eagles are solitary during the autumn, they mate for life and breeding takes place in late winter. The courtship ritual may involve dramatic flights, sometimes with the pair whirling down while clutching each other’s talons. The nests are generally found high in old trees, and expanded year after year. The largest recorded nest was 12 feet tall, 8 feet wide and estimated to weigh more than 2 tons! A clutch of two to three eggs is incubated just over one month, hatching in April or May. Both parents feed the chicks, with initial flights after 10-12 weeks. Longevity in the wild may reach 30 years.

It takes a lot of energy to power these raptors — scientists measured their resting heart rate at more than 100 beats per minute, and their body temperature exceeds 105 degrees Fahrenheit. While the diet is 80% fish, other prey includes ducks, gulls, snakes, muskrats and turtles. In addition to stealing food from smaller competitors, eagles regularly scavenge carrion, and this exposes them to poisons or lead in carcasses. Lead the size of a rice grain is sufficient to kill an eagle.

A bald eagle is capable of flying faster than 40 mph with good thermals, and its dive speed approaches 100 mph. When they hit the water in search of a fish, it makes an impressive display!  

Habitat is critical for bald eagles, especially in areas with regular human activity. Eagles favor sites near lakes, rivers and ocean bays, yet they need secure forest cover and minimal human contact, ideally half a mile from human residences. During the nesting period, eagles are very sensitive to disturbances and may abandon the nest in case of repeated events. This species will benefit greatly from ongoing conservation of critical habitat.

The bald eagle is revered in Indigenous cultures, and feathers or claws appear in many rituals. Some tribes consider eagles to be spiritual messengers from the gods. Federal law restricts possession of eagle parts to Native Americans enrolled in recognized tribes. Penalties for possession are high, so if you find an eagle carcass or feathers, leave them in place or call a game warden.

A new Congress in 1782 approved the Great Seal of the United States with a bald eagle clutching an olive branch and 13 arrows representing the existing states. Despite Ben Franklin’s preference for the wild turkey, the bald eagle was chosen as a symbol of courage and strength for a country freed from tyranny. Today we still use bald eagles on our most valuable gold and silver coins, with profits from the U.S. Mint directed to the American Eagle Foundation, a conservation group in Tennessee.

Ed Robinson’s latest book, “Nature Notes from Maine Vol. II: Puffins, Black Bears, Raccoons & More,” is available from the Harpswell Heritage Land Trust. All profits support HHLT’s conservation and education efforts.