Wednesday, October 19, 2011

A Bit about Eagles

Eagles are designated under the Family Accipitridae along with Kites and Hawks. 

Four eagle species, listed here in decending order by size:

Bald Eagle
Golden Eagle
White tailed Eagle
Steller's Sea-Eagle

Some Eagle Facts

-birds of prey with hooked bills and strong talons
-sexes have similar plummage
-males are smaller than females

The Golden Eagle is a rather solitary bird, rarely is it seen in flocks.  During breeding, Goldens pair up and build nests on cliffs or in tall trees.  Both mom and dad participate in incubation and feeding of the young.  Incubation takes approximately 44 days.  Chicks leave the nest at roughly 10 weeks.

Golden Eagles eat small mammals, snakes, birds and carrion.  They are seen mainly in the Western US and Canada in mountainous and plains areas. They have solid brown plumage with golden wash on the head and neck and a band of white on the tail.  Wingspan is 80-88 inches.  Length (from the tip of the bill to the tip of the tail)  is 30-40 inches.

The Bald Eagle has a distinctive white head and tail which does not develop until the bird is three or four years old.  Prior to that, the juvenile, or sub adult, is mostly brown.  Wingspan:  70-90 inches.  Length:  31-37 inches.

The Bald Eagle's territory stretches thoughout the US and Canada.  Their main food is fish, thus, they sometimes migrate depending on spawning patterns or when ice covers the water.  Unlike the Golden Eagle, Bald Eagles gather in flocks during migration and other non breeding periods.  Pairs stay together all year.  Courtship includes soaring side by side, chasing, and sitting close together and preening each other.  Copulation occurs at or near the nest site.

The nest and surrounding area, including water/feeding area is considered territory.  The Eagles will guard it from other birds such as Crows and Ospreys who may attempt to eat the eaglets.  Though the Bald Eagle prefers more room, a mile or two, they will tolerate other Eagles nesting as close as 150 yards- which is most common when there is good fishing nearby.

Two to four eggs are laid (two most commonly) in a large nest high atop a tree or cliff.  Nests are six feet in diameter, 4 to 10 feet deep, made of sticks and branches, sod, grasses and seaweed.  The Bald Eagles will often bring chunks of evergreen or deciduous green leaves into the nest to eat.  It is believed that nutrients from the green material are needed particularly during chick rearing.

The parents take turns incubating the eggs in 1 to 3 hour shifts.  The young hatch in 34-36 days, each several days apart. During the first two weeks, the parents both brood (sitting near the chick to keep it warm).  Both parents feed the youngsters.  After tearing off a bite-sized piece of meat, the parent puts it directly into the chick's bill (no regurgitation required!).  Feeding continues until the babies leave the nest. 

Eaglets back up to the edge of the nest and shoot their feces out.  There is usually a white wash surrounding the nest, which by the way, will most likely be used again and again for years.  The parents keep building on top of it, with fresh materials.  As Bald Eagles can live up to twenty years, sometimes the nest becomes too heavy for the tree.

At 6 weeks, the babies have grayish down covering their bodies.  During the second 6 weeks, feathers develop.  At 10-12 weeks, the babies begin to practice hunting.  They leave the nest a few weeks after that.

White-tailed Eagle's range in in northern Eurasia and Greenland.  Steller's Sea-Eagle is found in northeastern Asia.

Cornell Lab of Ornithology,
Golden Eagle head shot, Bald Eagle hunting: Wikipedia
Field Guide to the Birds of North America, National Geographic Society
Guide to Bird Behavior by Donald & Lillian Stokes
Encyclodedia of North American Birds  by Michael Vanner


  1. Thank you for this beautiful post about our national bird. I especially love the Golden Eagle.
    They have one in our local zoo that is not feeling very well and they can't let him back out into the wild. When we visit he always looks so sad.
    Feces shooting huh? Interesting, Lynn.

  2. Yep, must be some of that Poop Art the kids are into.

  3. They're magnificent birds. Thanks for posting!