Friday, May 30, 2008

May 31 migration prospects

Friday, May 30 -- I hadn't been paying much attention to the weather today, but Mark Shieldcastle pointed out to me that an interesting pattern was developing and that I should look at the maps. Sure enough, looking at the large-scale pattern, there's a large high-pressure area off to the east of us and a low-pressure area off to our northwest, and between the two of them there's a strong flow of air coming all the way up from Texas. Any concentrations of migrants that are still to the south of us are probably going to ride that train into our area during the night tonight. It's likely to be stormy overnight tonight and windy tomorrow, but still there could be a lot of birds around on Saturday, the 31st.

This late in the season, the variety is more limited than it was in mid-May. Some of the birds that are common now are just characteristic late migrants, like Red-eyed Vireo, Swainson's Thrush, and American Redstart. Among warblers there's an interesting pattern with Mourning, Canada, and Wilson's Warblers being among the latest to peak here: all three of these are species that migrate around the Gulf of Mexico instead of across it, coming around through Mexico and Texas rather than making the overwater jump from Yucatan to Louisiana. In Ohio, of course, these west-of-the-Gulf migrants overlap with Blackpoll and Connecticut Warblers, also late migrants, which come up mostly through Florida from their South American wintering grounds. Here it's not unusual to find Connecticut and Mourning Warblers together, but it would be very rare to find them together in the southernmost states of the U.S.

This period, right at the end of May, is still within the peak migration for Yellow-bellied, Alder, and Willow Flycatchers, and there are still some Leasts and Acadians moving through, making this a great time to study identification of these subtle birds. With any luck, the bird-banding demonstration at BSBO on Saturday (10 to 11:30) will include a few of these Empidonax flycatchers for some close-up study.

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