Paul Schmitt raises the question of size difference in the Bald Eagle nestlings being due to age instead of gender. I considered that. These nestlings are not mere chicks just out of the egg. They are hulking, huge, completely-feathered, birds, and they have been for weeks. I'm guessing that the younger one has had time to catch up, and they are at their full-grown male or female size by now. Admittedly this is just my surmise that in the case of such a long nestling period, the generalization that fledglings are adult-sized when they leave the nest might trump the fact that raptor eggs tend to hatch asynchronously giving the older chick a head start of a day or two. That day or two difference is now a small percentage or their total age. As usual I am perfectly willing to make guesses and interpretations based on very little information or personal experience, so again as usual I welcome word either way on this issue from actual ornithologists or people who have more studiously observed Bald Eagle youngsters at this stage.
--Dave Nutter
Begin forwarded message:
From: Paul <pschm...@stny.rr.com>
Date: June 02, 2012 11:01:41 PM
To: Dave Nutter <nutter.d...@me.com>
Subject: Re: [cayugabirds-l] Ulysses Bald Eagle nest progressHi Dave,I understand the size indicating male or female in adults, but couldn’t the size now be a matter of which hatched first? I can see a size difference in the two Redtail chicks at the Stewart Avenue bridge. The larger one also was further along in developing flight feathers.Anyone at the lab who could shed light on whether size differences show up before the young are even fledged?By the way, sounds like these are at about the same stage as the two in the nest near Corning. I need to check on them tomorrow to see if they are exercising their wings.Paul SchmittFrom: Dave NutterSent: Saturday, June 02, 2012 10:25 PMSubject: [cayugabirds-l] Ulysses Bald Eagle nest progressThis evening I again biked out NYS-89 to check on the BALD EAGLE nest near the Glenwood Pines restaurant in the Town of Ulysses. I saw no adults, but the two youngsters are out of the nest and into the branches of the nest tree. One bird (perhaps larger, therefore female) was rather sedentary, perched near the nest, picking at its talons with its bill and seldom opening its wings. The other bird (smaller, I think, therefore male) was quite active, "fluttering" from branch to branch.
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