Forecast and Analysis

Regional Migration Analysis: 24-30 August 2013

Andrew Farnsworth The Cornell Lab Aug 30, 2013

Continental Summary

Light to moderate movements were widespread across the country this past week, with each of the BirdCast regions experiencing some nice pulses of birds. Of particular note was the higher than anticipated magnitude and intensity of movements early in the period in the Southeast. Birds on the move this week included Green-winged and Blue-winged Teal, Least, Western, Pectoral, Upland, and Stilt Sandpipers, Common Nighthawk, and Tennessee, Magnolia, and Wilson’s Warblers among others.


The West continued with its typical pattern of late, with light to moderate movements across the region in areas where precipitation did not fall. As has been the case for the past weeks, the Central Valley of California experienced consistent local moderate movements through the period. Of particular note, however, is the more widespread movement of Thursday night, 29 August, when radars from central California East through portions of the Great Basin and even the far eastern reaches of Colorado and New Mexico showed light to moderate movements. Birds on the move this week included Northern Pintail, Least and Western Sandpipers, Red-necked Phalarope, Townsend’s Warbler, and Savannah Sparrow.

Great Plains

This forecast period was punctuated with pulses of localized light to moderate movements through the early part of the week, followed by slightly more extensive movements of the same magnitude to end the period. The eastern Plains saw light to moderate movements to start the period, and again to end the period, whereas more northerly locations experienced a weekend pulse followed by another pair of pulses mid and late week. The night of 29 August was the most extensive and intense of the period’s movements, with birds moving from the Canadian border South and East through Oklahoma. Birds on the move this week included Blue-winged Teal, Great Blue Heron, Great and Snowy Egrets, Sora, Buff-breasted, Least, Solitary, and Stilt Sandpipers, Short-billed Dowitcher, Yellow-throated and Red-eyed Vireos, Wilson’s Warbler, Yellow-breasted Chat, and Baltimore Oriole.

Upper Midwest and Northeast

A nice pulse of birds moved through the region to begin the forecast period, with moderate movements apparent beginning in the Great Lakes and ending in mid-Atlantic and New England states. An early week lull was followed by another pulse of moderate movements in the Great Lakes on Tuesday night, and a localized moderate flight in the New York tri-state area. This pattern continued into Wednesday night, and then expanded South to end the period. Northern New England also experienced a pulse of localized moderate movement on 29 August. Note that none of the week’s movements experienced the predicted moderate to heavy intensities, presumably because movement were more widespread and earlier in the period than anticipated, without a substantial period of migrants accumulating on the ground. Birds on the move this week included Green-winged Teal, Common Nighthawk, Least Flycatcher, Tennessee, Magnolia, Black-throated Green, Chestnut-sided, and and Blackburnian Warblers.

Gulf Coast and Southeast

The beginning of the forecast period brought heavier and more widespread movements than Team BirdCast expected, as birds were clearly itching to move and conditions were not as marginal as forecast. These movements largely continued as expected through the remainder of the forecast period, with primarily light to locally moderate movements scattered through the region. However, as predicted, another pulse of moderate movements occurred to end the period on 29 August, particularly from the Texas Panhandle East through the southwestern Appalachians to the Atlantic. Birds on the move this week included Blue-winged Teal, Pectoral and Upland Sandpipers, Eastern Wood-Pewee, Blue-gray Gnatcatcher, Ovenbird, Northern Parula, and Worm-eating Warbler.