Sunday, May 13, 2012

Bird Migration Forecast

Cornell's eBird website has released their bird migration forecasts for this week. I've excerpted the sections relevant to folks here in the northeast, but you can read the entire forecast here.

BirdCast Forecast: 11 - 17 May

High pressure will dominate much of the country during this forecast period. The West will experience widespread light to moderate migration this week, as high pressure and warmer temperatures build in across most of the region. Moderate to heavy movements will occur in the Great Plains, despite scattered precipitation that may inhibit movements locally. Despite largely unfavorable winds aloft for much of the period, most areas of the Upper Midwest and Northeast will experience moderate to heavy movements this week; the threat of scattered precipitation will diminish movements in some locations. The Gulf Coast and Southeast should see an influx of trans-Gulf migrants in the western Gulf early in the weekend, in the eastern Gulf early next week, and generally widespread moderate to heavy movements inland, despite some periods of unfavorable winds aloft and the threat of scattered precipitation early in the period. Birders in coastal areas should watch for potential fallouts through the early portion of the week.

Warbler migration in full swing

For many birders in the East, spring migration is nearly synonymous with looking for warblers. Next week should continue to offer excitement throughout North America. Throughout much of the Great Plains, Midwest, and Northeast, this next week promises to offer some of the best warbler watching of the spring with a wide variety of species and large numbers of singing males. By contrast, migration along the Gulf Coast will have slowed, with most migrants being females or 1st-spring birds. That said, there have been very good migration days even this late, including a fair number of rarities. While the best migration days may be past, this is still an excellent time to go birding.

The Connecticut Warbler is among the most enigmatic and highly sought warblers in North America. This species winters in South America and has a fairly narrow migration window. Even in Florida, this species is rarely noted before May (and it is very rare west of Florida along the Gulf Coast). While finding a Connecticut Warbler anywhere is always a treat, we expect a fair number of individuals to be on the move this week from Tennessee northward to Minnesota, Wisconsin, and Ohio; by late in the week birds are likely to appear in North Dakota and Ontario. This species is often best detected by song, and otherwise often remains hidden. When not signing, Connecticut Warblers are more likely to be found at isolated migrant traps, particularly in eastern North Dakota and Minnesota.



Connecticut Warbler migration map, May (all years). Note the presumed arrival in Florida after a trans-Caribbean flight from South America. Then quick movement north through the Midwest.

Upper Midwest and Northeast

Although winds aloft are forecast to be mostly marginal during the forecast period, the fact that the region may not see substantial and extensive precipitation suggests that migration volume will be moderate in many areas, with some locally heavy movements. In areas where precipitation occurs, the potential for local fallout conditions could develop; birders across the region should watch the passage of precipitation with this in mind. This is particularly true beginning early in the week, when any checking for migrants should include both passerine traps and inland lakes.

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