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Adult & Chick Sexual Size Differences-1

Bald Eagle Biology

My measurements show that the bald eagles in our area, southern British
Columbia, generally weigh between 5 and 12 pounds (closer average 7 -11 pounds) . When I repeat this to my Alaskan colleagues they point out they have caught several 13 pound birds. And I believe they do.

I actually suspect many are seasonally bigger here as well. An eagle stuffing itself for days on end on salmon gains great weight. Most of the eagles I caught were during the summer when food was less available – and they had to work harder to get it. The general breakdown is 5 - 8 pounds for males and 8 -12 pounds for females.

It is interesting to note that in each of the first 5 years of an eagles life its wingspan gets shorter and has less width. The big soaring wings of the juveniles, so necessary to get them to their first free food, which might be 1000 miles (1600km) with minimal energy expansion -- the northern salmon runs -- get shorter and better adapted to fast maneuverable flight to match the eagles flying needs which become greatest when it has to be able to hunt within a home range to support a family. Before that it has more freedom to soar and the larger sails are obviously better adapted to that. A female just off the nest might have 6'4" wing span but at maturity it might only be 6'.

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Bald Eagle Nestling Age Classes-1

Bald Eagle Biology
Bald Eagle Nestling Age Classes

By: David Hancock:
Bald Eagle Biologist

Bald Eagle Nestling Age Classes:
(Waiting for DH photos)

Chicks- Colour/Size and Estimated Age

Class 1.
White and Small. Never left alone
for more than 2-3 minutes 1 - 10 day days
Class 2.
Starting Grey and Small. In warm
weather left alone 1-10 minutes 1 - 3 weeks old
Class 3
Grey sit up in nest. Can be left
alone in warm weather 10-+ min. 4-5 weeks old
Class 4
Brown feather just starting to
show in a few rows 6-7 weeks old
Class 5
Brown feathers showing as
dominant tracks 8-9 weeks old
Class 6
Brown and full size body:
No grey down showing. 10-12 weeks old
Class 7
Fledglings: Uniformly brown:
Chicks fledge at 80 to 90 days of age.
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Watching Eaglets Grow

Bald Eagle BiologyI've recently added an area for eagle pictures and statistics to my website. At first glance, that may sound a bit redundant at best, given all the websites around the world with cams and discussion but as I wandered from site to site, enjoying the antics of the eaglets and wondering at the fact that some were near fledging while others were newly hatched, I found that something was missing.

I might notice that one eaglet has stubby down-covered wings while another that I thought was about the same age has suddenly sprouted feathers and, having a bit of scientific curiosity, my immediate question is "just how much older is the eaglet with the feathers?"

That isn't as easy to discover as you might think. At the very least, it requires checking the web sites for the two eaglets in the hope that they have an announcement of the hatch dates posted. If not, one needs to wander through the website blogs and the various forums where that nest is discussed until one finds the date in question.

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Do You Want a Bald Eagle Nest in Your Yard?

Bald Eagle Biology

Bald Eagles: ----- Constructing Artificial Bald Eagle Nests to Give the Eagles a Head Start.

The Bald Eagle has invaded the Vancouver BC urban area. In the past years, lacking adequate tall trees sturdy enough to support their bulky nest, the eagles has started to nest in man-made structures.

Do you want a Bald Eagle Nest in Your Yard? In your neighborhood Park?

If so we can now help put it there!


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