Path: utzoo!utgpu!news-server.csri.toronto.edu!mailrus!cs.utexas.edu!yale!mintaka!olivea!oliven!mjm From: mjm@oliven.olivetti.com (Michael Mammoser) Newsgroups: rec.birds Subject: Re: Early migrant, and Friday Message-ID: <49253@olivea.atc.olivetti.com> Date: 9 Aug 90 05:28:31 GMT References: Sender: news@olivea.atc.olivetti.com Lines: 43 In article , grp@unify.uucp (Greg Pasquariello) writes: > > It seems I have a migrant already! This morning, one of the Selasphorus > hummingbirds showed up at my feeder. I believe it is a rufous, but it's a > female or young male, and I'm not sure yet. In the next few days, I hope to > get a close enough look to determine, based on the outer tail feathers, but > this is iffy. > > I suspect that it is a young male, probably > dispersing southward on a leisurly migration, and I also suspect that it's a > rufous (as I said), because that would be much more likely in my area (Sierra > foothills). > > After doing a little further research, I have discovered that both Rufous and > Allen's Hummingbirds migrate in July and August, so the bird is not as early > as I thought. Also, according to Arnold Small, Allen's will sometimes use > mountain meadows in the Sierra for southbound migration. I still feel it's > rufous, however I'm still not sure. I have banded both Rufous and Allen's Hummingbirds, and the difference in the width of the outer tail feathers is measured in millimeters, with the threshold being about 3 mm. Another characteristic concerns rectrice two, the second one from the center. Rufous Hummers will have varying degrees of emargination on one or both sides of this feather, depending on age and sex. This emargination is virtually absent on Allen's. Both of these characteristics are darn near impossible to see in the field without having the bird in hand. Another problem with Rufous are the immature males. They generally acquire the bright orange gorget by the time of fall migration; September or so. The problem is that they won't go through their first full body molt until sometime prior to spring migration. During this time they will have a bright gorget with an all-green (juvenile plumage) back, looking for all the world like an Allen's male. The above mentioned tail feather characteristics are still applicable but, again, are difficult to see in the field except in the hand. I would suggest that the best way to get these guys on your life list is to go out and find males in the springtime. One problem is that both these species tend to be coastal at this time. Hope this helps. Mike