Saturday, May 19, 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: 18 - 24 May

While team eBird is in Alaska, our April eBirder of the month, Benjamin Van Doren, is our guest BirdCaster. Benjamin has a talent for understanding migration, developing an ambitious project to gather morning flight data from dozens birdwatchers in the Northeast that was recognized with a 5th place in the prestigious Intel Science Talent Search. Take it away, Benjamin!

Many areas of the West will experience light to moderate movements, especially the southeastern portion (New Mexico and environs), when not dealing with precipitation. Strong, far-reaching southerly flow over the Great Plains will spur moderate to heavy passage, interrupted by precipitation with potential to put down migrating birds. The Upper Midwest will also see favorable conditions punctuated by rain, as light to moderate movements continue to the east when not hampered by precipitation. Texas and some parts of the western Gulf Coast will see conditions favorable for movement, but scattered precipitation and subpar winds will slow migrants’ tracks through the Southeast, at least until late next week.

Western Sandpiper

Western Sandpiper is one of the most abundant shorebirds in North America, belonging to the assemblage of small shorebirds frequently referred to as "Peeps". This week, Western Sandpipers will be streaming north toward their breeding grounds, many having already arrived at staging areas in Alaska. Western Sandpiper is a common migrant along the Pacific Flyway in spring and fall, but this species migrates on a broader front in fall, occurring throughout the continent and even to the East Coast. It winters along the Southeast and Gulf Coasts, stretching south to Panama and northern South America (unlike the similar Semipalmated Sandpiper, which winters mainly in South America and the Caribbean). Spring migration is more focused for Western Sandpiper, however, and the species is exceptionally rare in the Northeast at that time. Small numbers move mainly toward the northwest from wintering areas in the Southeast and Caribbean, bypassing the Northeast altogether. Indeed, finding a Western Sandpiper among the hoards of Semipalmated Sandpipers moving through the Northeast is a rare treat in spring. This week, look for Western Sandpipers along the Pacific Coast, and across the interior of the continent.

Weather Forecast

The period will begin with high pressure covering the eastern seaboard as a storm tracks from the northern plains toward Hudson Bay. This will open up a period of south winds up through the Midwest to the Great Lakes. Farther east, winds will remain light under high pressure until a weak cold front crosses the East early next week. This front will be followed by another high pressure and light winds. Across the West, the period will begin tranquil as high pressure dominates. But a storm system will come onshore in the Pacific Northwest early next week and eventually work into the Plains by the end of the week, leading to another strong period of south winds from the Gulf to the northern Plains and Great Lakes.

Upper Midwest and Northeast

The forecast period begins as high pressure dominates the northeast, with conditions favorable for migration west of New York, likely spurring moderate to heavy migration events in that area. Light to moderate movements may still occur to the east, however, ahead of an advancing rain-bearing front, which will then hamper migratory passage until later in the period. Southerly winds return towards the end of the forecast period in the western part of the region, along with the potential for sizable movements. However, depending on the strength of the wind, some light movement may still occur when winds aloft are not  southerly as birds continue to surge towards their breeding grounds. These movements may occur at low altitudes, sometimes below the reach of radar, as birds seek the strata of atmosphere most advantageous for northbound flight. Fronts will bring rain to the area both early in the week and toward the end; birders especially in the Great Lakes region should be aware of possible localized fallouts as masses of migrating birds interact with advancing precipitation.

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