[Tweeters] Reliably aging Golden Eagles in the field

Filip Tkaczyk pathwithaheart at hotmail.com
Sun Jan 10 12:18:55 PST 2010

I was wondering if any experienced birders/naturalists out there have found ways of estimating maturity of a golden eagle once it has hit adulthood? I am not after necessarily a means of estimating the exact number of years of life... more a general sense of age, i.e. mature, old, very old or something along those lines.

I am aware that juvenile birds show significant areas of white on the upper tail and under-wings. This fades to darker plumage with age, until eventually a fully mature bird shows practically no white at all. But, what then? Do the golden tones become more extensive with age? I understand that some variation might be observed from bird to bird, but has such a pattern been observed regarding areas of gold on the bird relative to age?

This query was inspired by observing a pair of golden eagles the other day...

Had a wonderful experience watching golden eagles hunting in the hills around Elk Heights yesterday. On several occasions the group of naturalists I was with got to see an adult golden eagle up close and personal. We saw this bird up close on several occasions, from between 40 & 80 feet distance while inside a vehicle. We noted that this bird was very large, and made the accompanying ravens sitting in the tree with it appear as small as crows. When this bird flew, it look even larger. Its tail and under wings were completely dark, mottled in subtly darker and lighter patterns.

We noted how extensive the pale, golden colors spread over most of the head, significant areas of the wings and back. Another eagle was nearby and appeared to be somewhat smaller with proportionally longer wings. We assumed the first to be female and the second, male. Though, we were not certain of this by any means. Sexing birds of prey accurately is at times challenging during fleeting encounters in the field....

We noted that the larger of the two birds, the one we guessed to be female, appeared to have much more extensive areas of pale golden tones.

So, we wondered... Was she much older than her mate? Was this simply a color variation for this particular bird?

I would appreciate lots of feedback on this!

Thanks in advance,

Filip Tkaczyk

Seattle, WA
mailto: pathwithaheart at hotmail.com

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