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Today through Friday has potential to see winds transport waterfowl, gulls, and other late migrants and irruptives into the Northeast and Great Lakes. Additionally, snow cover may force sparrows and open-area species like pipits, longspurs, Snow Buntings, and larks to…

Favorable conditions for light to moderate flights begin and ends the period for the West as Black-bellied Plover, Lesser Yellowlegs, Willow Flycatcher, Swainson’s Thrush, Townsend’s Warbler, Virginia Warbler, and Blue Grosbeak are on the move, while the moderate to heavy flights that will include White-rumped Sandpiper, Short-billed Dowitcher, Least Flycatcher, Philadelphia Vireo, Blackpoll Warbler, Chestnut-sided Warbler, Wilson’s Warbler, Rose-breasted Grosbeak, Savannah Sparrow and White-crowned Sparrow navigate around some serious weather in the first half of the period and quiet markedly with that weather’s departure to end the period.

Thanks for all the memories! BirdCast automated forecast and live migration maps for Spring 2018 will be deactivated until 1 August 2018 – the last forecast map was published for the night of 31 May 2018, and the last live migration map will post on 15 June 2018. Please check back often for additional comments and posts on the spring 2018 season and the arrival of the farm migration maps on 1 August!

As the spring migration winds down for most species, this forecast period sees early week light to moderate movements in the West that feature Common Nighthawk, White-throated Swift, Warbling Vireo, Cedar Waxwing, and Gray Catbird and mostly moderate flights in the East that feature late season shorebirds, Least Tern, Yell0w-billed Cuckoo, Acadian Flycatcher, Alder Flycatcher, and Cedar Waxwing among other late season passerine migrants.

All but the latest of migrants already passed, this week saw in the primarily scattered light and highly localized moderate movements across the West, with late migrants featuring Olive-sided Flycatcher, Willow Flycatcher, Cedar Waxwing, and Townsend’s Warbler, while the East saw its light to moderate flights concentrated in the center of the country and featuring primarily departures of Least Sandpiper, White-rumped Sandpiper, Short-billed Dowitcher, Cedar Waxwing, Swainson’s Thrush, Tennessee Warbler, Blackpoll Warbler.

Moderate movements, particularly in the latter half of the period from California and the Desert Southwest, included Spotted Sandpiper, Wilson’s Phalarope, Olive-sided Flycatcher, Western Wood-Pewee, Swainson’s Thrush, Yellow-breasted Chat, Western Tanager, and Black-headed Grosbeak in the West, while the migration machine kicked into a higher gear with moderate to heavy flights in the East that included Least Flycatcher, Philadelphia Vireo, Veery, Mourning Warbler, Bay-breasted Warbler, Black-throated Green Warbler, Yellow-breasted Chat, Rose-breasted Grosbeak, Dickcissel, Orchard Oriole, and Baltimore Oriole.

An odd week in the East will feature good conditions for trans-Gulf flights (and fallouts), some early period moderate to locally heavy flights in the Plains, and a more quiet than usual Northeast with numerous species on the move including Green Heron, Black-bellied Plover, Lesser Yellowlegs, Caspian Tern, Blue-headed Vireo, Prairie Warbler, Yellow-throated Warbler, Worm-eating Warbler, Savannah Sparrow, and Summer Tanager, while the West sees a quiet heart of the period bookended by light to moderate flights that will included Lesser Yellowlegs, Long-billed and Short-billed Dowitchers, Black Tern, Plumbeous Vireo, Wilson’s Warbler, Hermit Warbler, and Lark Bunting.

With peaks of spring movements in the rear view for most species, this week will see scattered light flights across much of the West, with moderate flights along the eastern front of the Rockies, that will feature Black Tern, Cordilleran Flycatcher, Willow Flycatcher, MacGillivray’s Warbler, and Blue Grosbeak, and moderate to heavy midweek flights where and when precipitation does not fall in the East, featuring Black-bellied Plover, Black Tern, Olive-sided Flycatcher, Alder Flycatcher, Yellow-bellied Flycatcher, and Mourning Warbler.

From Monday to Thursday many areas of the West see light to moderate migration featuring Dunlin, Willet, Least Sandpiper, Olive-sided Flycatcher, Yellow-rumped Warbler, and Green-tailed Towhee, while several disturbances passing through the East spawn fallouts along the Gulf Coast and moderate to heavy movements of numerous shorebirds, Blue-gray Gnatcatcher, Black-and-white Warbler, Prothonotary Warbler, Palm Warbler, Rose-breasted Grosbeak, and White-throated Sparrow in advance of frontal passages.

A reasonable quiet late migration season week in the West featured movements of Black Tern, Olive-sided Flycatcher, Swainson’s Thrush, Gray Catbird, Northern Waterthrush, American Redstart, particularly in the Desert Southwest and northern Rockies, while moderate to heavy flights in the East early in the week, featuring White-rumped Sandpiper, Sanderling, Black Skimmer, Eastern Wood-Pewee, Marsh Wren, Saltmarsh Sparrow, and Orchard Oriole, subsided as a more early spring like air mass arrived.

Scattered precipitation across the region this period will add a new dynamic to West, with light to moderate movements featuring Common Nighthawk, Western Wood-Pewee, Eastern Kingbird, Western Tanager, and Lazuli Bunting where precipitation is not falling mostly early in the week in the Southwest and central and southern Rockies, while an early period blast of moderate to heavy movements featuring White-rumped Sandpiper, Common Nighthawk, Willow Flycatcher, Yellow-bellied Flycatcher, Philadelphia Vireo, Tennessee Warbler, and Blackpoll Warbler gets swept aside with the passage of a strong frontal boundary in the middle of the week.

A brief pulse of light to moderate flights that will include American Avocet, Marbled Godwit, Western Sandpiper, Western Kingbird, Barn Swallow, Black-headed Grosbeak, and Bullock’s Oriole on either end of the forecast period highlight otherwise unfavorable conditions across the West, while a relatively weak front drifts east mid week bringing light to moderate flights of Osprey, Greater Yellowlegs, Semipalmated Sandpiper, Ruby-throated Hummingbird, Purple Martin, and Tree Swallow first to the northern Plains, then the Great Lakes, and finally the Appalachians and portions of the eastern seaboard.