Monday, 18 May 2015

[cobirds] Re: Welchester Yellow-throated Vireos

I am certainly not discounting that there are three yellow-throated vireos because I did not see them. The main reason is that separating males from females is not really possible. To suggest that a young bird can be identified separately from adults stretches this even further. I have looked at hundreds of photos of yellow-throated vireos and have not found a single one separating males from females. The same goes for every field guide I possess.
Norm Erthal
Arvada, CO

On Saturday, May 16, 2015 at 9:39:28 AM UTC-6, Norm Erthal wrote:
The three yellow-throated vireos at Welchester are very unlikely for several reasons. First, 3 together in one location in Colorado would be unprecedented. This does mean it cannot happen, but great care should be taken to be absolutely positive about the identification. Yellow-throated vireos along with most other vireos are not sexually dimorphic. This means males and females have the same plumage and are not separable in the field. Young birds attain full adult plumage very early in their life. Finally most passerines have the adult male generally migrate south before the females and young and return north in the spring prior to females to establish territories. Females are next to leave followed finally by young birds. It would be nearly unfathomable for adult birds and first year birds to reestablish contact on the wintering grounds and then return north as a family group. Without photos of each of the three birds, this sighting would not pass muster with experienced birders.

Norm Erthal
Arvada, CO

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