Friday, May 04, 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: 4 - 10 May

As several low pressure centers and their associated precipitation progress across the country, migration levels will vary more than usual. Primarily light to moderate movements will occur across more southerly portions of the West, whereas precipitation and generally unfavorable winds aloft will keep most migrants in more northerly portions grounded. Although a few areas of the Great Plains may see moderate to heavy movements early in the period and scattered movements for the remainder of the period, most areas will experience rather poor conditions for migration on most nights this week. Poor migration conditions will prevail more often than not across the Upper Midwest and Northeast, but birders should watch closely for marginally favorable migration conditions to develop, possibly producing moderate movements and fallouts may occur. The Gulf Coast and Southeast are in for another week of moderate to heavy movements, punctuated by a strong possibility of fallout conditions from Texas to the eastern Gulf late in the period.
See the animated forecast maps for the upcoming week here.

Bobolink

Bobolinks have recently arrived in some areas of the eastern US, and this week birders should see more widespread arrivals of this species in the East and Great Plains. Birders listening at night or during early morning may hear the distinctive “boink!” or “pink!” flight calls of passing Bobolinks, and those fortunate enough to have nesting Bobolinks close by will soon hear their amazing song, described by Arthur Bent as a “bubbling delirium of ecstatic music.” Bobolink is a species of special concern in some areas because of the loss of prairie, mixed grasslands, meadows, and agricultural areas producing hay. In addition, Bobolink is a long-distance migrant, with North American breeders moving primarily in the trans-Caribbean assemblage of migrants and wintering in the pampas of Brazil and Argentina. Members of the Lab's eBird and Conservation Science teams are collaborating with The Nature Conservancy and New York Natural Heritage Program on a project funded by NYSERDA that brings together multiple datasets and analyzes bird migration data to help prioritize areas for wind energy projects that minimize biodiversity impacts. This project will also provide a forum for communicating this information to representatives of the wind industry. Bobolink is one of the focal species for this project, since its habitat requirements, migration strategies, and distribution make it an ideal study subject.

Forecast

The forecast period will start off with continued south winds across much of the eastern U.S. A series of low-pressure systems will track east across the Great Lakes and Northeast, and push a front southward. The front will eventually reach all the way to the deep South by the middle of the forecast period, with north winds dominating most areas east of the Rockies. This front likely will put the brakes on the first major influx of Neotropical migrants that has been occurring across the East this week. As migrants are stalled behind this weather, it may set up conditions for a major flight if favorable conditions should return in mid-May. High pressure off the Pacific Coast will keep winds mainly northerly along the West Coast for the entire forecast period with little precipitation expected.


Upper Midwest and Northeast

The period begins with scattered precipitation and largely northerly and unfavorable winds aloft across the region; migrants will likely be grounded in many areas. Areas that do not see precipitation, however, will experience scattered moderate movements despite the largely unfavorable winds, given the time of the year and the available pool of birds trying to reach breeding areas. Much of the remainder of the forecast period will exhibit a similar pattern, with precipitation and unfavorable winds aloft expected to continue in most areas. Notable exceptions to the aforementioned pattern will include a moderate movement in western portions of the region to begin the week, including a potential for fallout conditions across the western Great Lakes and Upper Mississippi River valley, and moderate to locally heavy movements east of the Appalachians on Monday night and Tuesday morning. Birders in coastal portions of the region should watch the extent and intensity of rain from midweek through the remainder of the period, as the potential exists for migrating birds to interact with large areas of precipitation. If birds are migrating into these areas of precipitation, there is a strong potential for fallout conditions. Migrant traps should be checked from midweek through the remainder of the period, including inland water bodies, which will likely receive input from drop-ins of waterfowl, gulls, and terns.

As with the Great Plains, this week will mark the beginning of peak movement. The Upper Midwest has already seen some great days with high warbler diversity, and more such days are to be expected. By the end of next week, almost any species of warbler will be possible (including later migrants such as Blackpoll and even Mourning Warblers), although later migrant flycatchers like Willow, Alder, Yellow-bellied, and Olive-sided will not be expected to arrive in most areas until late in the following week. Early migrants like most waterfowl, Yellow-rumped Warbler, Chipping Sparrow, Palm Warbler, and Ruby-crowned Kinglets will become less and less common as the month progresses.

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