Monday, May 12, 2008

The next migrant waves

As of today, Monday May 12, the main part of the second migration wave has not arrived here. Although most of the migrant species are present, at least in small numbers, we have not yet seen the big influx of Magnolia, Chestnut-sided, Bay-breasted, and other warblers that would characterize the mid-May wave. This is my impression from field observation and it’s backed up by conversations with Mark Shieldcastle about the current state of the migration as reflected at the main BSBO banding site (on the Navarre Unit of the Ottawa Natl Wildlife Refuge, about 4 miles east of the Magee boardwalk). The banding station maintains a standardized constant effort throughout the migration season, so its results are highly comparable from year to year. This year, the first part of the migration has been unusually protracted, so that early-season migrants like Yellow-rumped Warblers and White-throated Sparrows are still around in unusual numbers. Meanwhile, the mid-May explosion of Magnolias and their ilk has not yet begun. (Yes, there are a few around, but not thousands. Not yet.)

What this means is that a LOT of migrants are still to the south of us. I’ve been studying weather forecasts to try to figure out when the next wave will hit. The winds have been mostly out of the north for the last several days, and will continue to be northerly most of the time for the next four days. Under current predictions, the winds will shift to the southeast by early morning Tuesday (May 13) and will continue to be out of the southeast Tuesday night, and if that holds up, I expect there will be a moderate arrival of migrants on Wednesday morning, May 14th. I don’t think it will be a massive fallout but it could turn out to be anything from fairly slow to very good. Then the winds are supposed to swing around to the northwest again by Wednesday night and stay northerly through Thursday. Right now the predictions show the winds going to southwest by Friday morning and staying that way for a while, and on that basis, I think there should be a major arrival of migrants next weekend, May 17th and 18th. This should mean the biggest diversity of the season for the area, with best mix of warblers, a good arrival of vireos and flycatchers, and generally very exciting birding.

No guarantees, of course, because the weather forecasts could change in the next few days. But right now it looks like Wednesday May 14th could be fair to good, and Saturday May 17th could be good to excellent.


Ain't No Sin said...

Thanks, these predictions are invaluable for those of us that have to contend with planning a hopefully productive birding trip around work and other obligations. Even better Saturday the 17th fits my schedule quite well!

Mason Flint said...

I'll second that thanks. I'm flying into Detroit Thursday afternoon and plan to bird Crane Creek and nearby spots on Friday, Saturday and Sunday. I sure hope your prediction turns out to be accurate! I'm a Seatteite who hasn't birded in the midwest during peak migration for nearly more than 25 years!

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