Migration Report: 11 – 17 May 2012

Benjamin Van Doren The Cornell Lab May 18, 2012

Diversity and abundance of migrants remained high across much of the US during this forecast period. (See last week’s forecast.) Presumably, this period and the next will be the last to have such diversity and abundance during this spring season, as many migrants have arrived or will soon arrive at their breeding destinations. Moderate to heavy movements occurred more often than not across the eastern half of the country, whereas widespread light to moderate movements were the norm in the West. See below for a bit more detail on the happenings of the past week!

Last week’s radar animation can be seen here.

Black-billed Cuckoo, Shawnee NF, Illinois. Photograph by Daniel Behm.

Black-billed Cuckoo, Shawnee NF, Illinois. Photograph by Daniel Behm.


Light to moderate migration was the norm in many areas of the west during this forecast period. High pressure and increasingly warm temperatures facilitated movements across the region. Some areas experienced locally heavier movements, particularly in portions of northern California and the Pacific Northwest.

Diversity is peaking in many areas, as evidenced by good numbers of migrants in several areas. A nice movement was reported by Bob Archer and Adrian and Christopher Hinkle at Mt Tabor in Portland, including good numbers of Townsend’s Warblers and Western Tanagers. Spanaway Marsh and Fort Steilacoom Park also had evidence of recent arrivals. Additionally, Yellow Warblers are moving north, with thefirst record from Alaska coming in the past week.

Great Plains

Migration volume was generally moderate to heavy in many areas away from precipitation and the passage of a relatively weak frontal boundary during the forecast period. The frontal boundary passed through the region early in the weekend, generally diminishing migration amounts to scattered light movements in its swath. However, as high pressure built in behind this over the course of the week, many areas began to experience increasing migration volume though the middle of the week.

Jon King had a good movement of Tennessee Warblers, among other migrants, early in the period in Douglas County, KS, and Craighead Forest Park in Arkansas, showed similar evidence of passerine movement from the weekend. Shorebirds also continue to pour through the region, particularly in National Wildlife Refuges such as Squaw Creekin Missouri.

Upper Midwest and Northeast

Friday saw high pressure dominating the scene, with cooler temperatures and unfavorable winds keeping migration amounts light in all but the most western portions of the region. However, the weekend saw conditions gradually improve and shift eastward, spawning moderate to heavy movements in a number of areas over the weekend. Although scattered precipitation, some of which was intense, kept migrants grounded where it occurred, locally heavy movements occurred across the region for the duration of the period among more widespread light to moderate movements.

Gulf Coast and Southeast

Moderate to heavy migration continued for much of the week in many areas around the region, particularly in Texas after the passage of strong storms early in the forecast period. As these storms continued east, migrants in close proximity to them mostly stayed on the ground.

The storms produced numerous fallouts in Texas and Louisiana, with good diversity and numbers in many areas. Blackburnian Warbler made a good showing in a number of reports, including John O’Brien’s observations from Houston. The species was also reported from Oyster Creek Park in good numbers. Along the coast, migrant diversity and numbers were good on Saturday, with evidence of a fallout at Smith Oaks in High Island, TX and Peveto Woods in Cameron County, LA.