For the Birds: Bald Eagle: Our Local Treasure

Saturday, June 30, 2012

Bullocks Oriole near Bald Eagle
Photo by Lyn Topinka
By Christine Southwick

Faster than a speeding car;
More powerful than other North American raptors; 

Able to lift prey heavier than its own weight; 

It’s a bird; It’s our national symbol; 
It’s the Bald Eagle

Ever wonder why a bird with a magnificent white head is called “Bald”? The word was “balled” in Middle English and meant “shining white”.

Juvenile Bald Eagle. Photo by Leah Serna

The Bald Eagle takes four to five years to sexually mature, and doesn’t acquire its white head and tail until then. Juveniles have a black beak, and are brownish all over, with more white patches showing each year until they reach maturity.  Once mature, they mate for life, only looking for another partner if something happens to their mate.  Like most raptors, the female is larger than the male; that’s called sexual size dimorphism.

Bald Eagle with prey, being chased by gull
Photo by Doug Parrott

Classified as a fish eagle, the Bald Eagle has specially adapted toes, with structures called spicules, which allow them to grab and hold fish, with gripping power ten times greater than a human’s. With their keen eyesight, estimated to be at least four times greater than humans, they can easily spot fish, locate ducks, or find dead salmon, a mile or more before swooping down and grabbing their prize with those strong talons. Their wickedly curved beak can easily tear through scales, feathers. Skin, or fur.

The Bald Eagle is unique to North America, with the largest eagles in the North, and gradually becoming smaller, with a smaller sub-species in Florida.  Bald Eagles in our area are mostly resident, with some going to Alaska in the summer.  Many thousands congregate on salmon-spawning rivers in B.C. during January and February.

Bald Eagle claiming Crow's intended meal
Photo by Bill Anderson

Bald Eagles are “apex” predators, meaning nothing hunts a healthy adult.  Being at the top of the food chain makes them vulnerable to toxins eaten by their prey. DDT, a powerful insecticide, caused the thinning of all raptor egg shells, and almost eliminated the Bald Eagle and other raptors, before DDT was finally banned in North America.

Bald Eagle Fish meal.
Photo by Patricia Damron

Bald Eagles have been protected since 1918, but some continue to be shot, often due to a misconception that Bald Eagles eat young farm animals. Being opportunistic feeders, they will eat dead farm animals and road kills, but prefer to stay around large fish-filled bodies of water ringed by large mature trees.  They use their nests repeatedly, and require large strong trees to hold nests that can weigh more than a ton, and may be thirteen or fourteen feet deep.

Although taken off the Endangered List in 2007, it is still illegal to harm Bald Eagles, disturb their nests, or even possess their feathers.

Christine Southwick is on the Board of the Puget Sound Bird Observatory and is their Winter Urban Color-banding Project Manager. She is a National Wildlife Federation Certified Wildlife Habitat Steward, having completed their forty hour class. We're happy that she is sharing her expertise with us about the birds in our backyards.

For previous For the Birds columns, click on the link under the Features section on the main webpage.


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