Bald Eagle Physiology
Eagle Family © Scott Kelly, Wild4Photos.com
How do bald eagles control their body temperatures?
Eagles adapt to the changes in temperature very efficiently. They have an under layer of fluffy down feathers under their outer feathers to insulate them from the cold. They “thermoregulate” (control their temperature) by panting with their mouth open or through heat loss through their unfeathered legs and feet. Eaglets are able to “thermoregulate” when they reach the age of 10 – 14 days old. Until then, the adult parents stays close to the young so they do not become too cold.
What is counter-current heat exchange in bald eagles?
Bald eagles have arteries and veins in their legs and feet positioned very close together. Warm blood flowing from the body toward the feet passes right next to the cold blood returning from the feet to the body.
Heat transfers from the outgoing blood to the incoming blood, warming the blood returning to the body and cooling the blood going to the feet.
Why It Matters
This system reduces heat loss through their feet when standing on ice, snow, or cold water. Their feet can remain near freezing temperatures without the bird losing body heat, saving energy.
How It Works in Practice
Blood reaching the toes is already cooled down, so the toes don’t conduct much heat to the environment. Blood returning to the body is pre-warmed, so the eagle maintains its core temperature efficiently. This is especially important because bald eagles often perch in cold water or snowy areas while hunting.
How long can bald eagles reproduce?
Eagles are thought to be able to reproduce throughout their lifespan, but little documentation is available. One eagle has been documented successfully raising young in her 26th year.
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