Migration Report: 25 – 31 May 2012

Benjamin Van Doren The Cornell Lab Jun 01, 2012

This forecast period (view last week’s forecast) saw what were likely the last major movements of this spring’s migration, though some birds will continue migrating through the 1st and 2nd weeks of June. The West experienced several nights of light to moderate movements, particularly along the Pacific coast. Storms and a frontal passage in the Great Plains kept birds grounded in their wake, though light to moderate movements occurred on many nights. Widespread light to moderate movements, particularly along the coast, occurred in rain free parts of the Upper Midwest and Northeast. And the last of the heavy movements for the season occurred in portions of Texas and Louisiana, amidst widely scattered precipitation and widely scattered light movements in the Gulf Coast and Southeast region. See this week’s animated radar maps for a more detailed visualization of the week in migration.

Red Knot and Ruddy Turnstones, Port Mahon DE. Brian E. McCaffrey

Red Knot and Ruddy Turnstones, Port Mahon DE. Brian E. McCaffrey


Amidst scattered precipitation, light to moderate migration occurred in many areas to begin the forecast period. More intense rain the northern Rockies and Great Basin shut down many movements there, as other parts of the region continued to see similar migration volumes through the weekend. For the duration of the period, migration was primarily light with some locally moderate movements. This was true particularly for coastal areas from California through Washington, all of which experience more extensive moderate movements from Monday through Thursday.

Coastal movements of passerines continued this week, including what are probably the last waves of songbird migrants through places like Mt. Tabor Park in Oregon.

Great Plains
Unfavorable conditions, including scattered precipitation, began the period in the northern and central Plains states, with more favorable conditions in the southernmost reaches of Kansas and Oklahoma. Moderate movements occurred over these southern states, whereas scattered light movements were the norm for much of the remainder of the Plains. By Sunday more favorable conditions associated with high pressure just east of the Rockies facilitated more widespread light to moderate, and even locally heavy, movements north to the Dakotas. However, some areas of the Dakotas saw migration shut down in scattered but intense thunderstorms. As a frontal boundary organized and moved east across the region, most movements were light and locally moderate. In the wake of frontal passage, migration volumes were minimal, with primairly widely scattered light movements as the norm through the end of the forecast period. Note, however, that some areas of the northern Plains experience locally heavy movements toward the end of the period, presumably representing some of the last big pulses of migrants to move through the region this spring.

Good migrant diversity continued in the border region, for example, at Park Point in MN. This diversity was also evident at Wisconsin Point, WI, between storms, as reported by Ted Keyel and Tom Prestby.

Upper Midwest and Northeast

Widespread light movements with a few locally moderate movements began the period, with an exception being the far western Great Lakes; a frontal passage brought unfavorable winds and colloer temperatures, mostly shutting down movements there. By the end of the weekend, the light movements continued over New York and New England while moderate and even locally heavy movements occurred in much of the region west of the Appalachians under warmer conditions and light winds associated with a stalled front. Storms in the western Great Lakes shut down movements where they occurred. As low pressure organized and then moved through the region during the remainder of the period, migration diminished to widely scattered light movements by the end of the forecast period. Note, however, that coastal areas from Virginia through Long Island continued to see sporadic light to moderate movements through the end of the period when storms did not keep birds on the ground.

Several eBirders had the good fortune of logging some nice Ruddy Turnstone numbers on the Delaware Bay shore, the south shore of Long Island, and in Rhode Island. Additionally, passerine migration, though winding down, was in good effect in coastal Maine, particularly on Monhegan Island.

Gulf Coast and Southeast
This region continued to experience much the same pattern as previous weeks, with widespread moderate to heavy movements over Texas and portions of Louisiana to begin the period and much diminished movement farther east. The remainder of the period beginning late in the weekend saw migration volumes diminish regionwide, and areas that saw precipitation saw migrants stay grounded. Note the dearth of activity over Florida and the Southeast coastal plain during much of the period. The paucity of birds was probably a function of a much depleted flow of migrants from the Caribbean due to the late date and the impending arrival of Tropical Storm Beryl. Additionally, the decreasing volumes seen in more western portions of the region also were likely harbingers of the tail end of most moderate to heavy movements through the region this spring.

Posted 31 May 2012 by Andrew Farnsworth, Brian Sullivan, Marshall Iliff, and Christopher Wood of the Cornell Lab of Ornithology and David Nicosia of NOAA, on behalf of Team eBird and BirdCast.