Migration Forecast: 9 – 15 March 2012

Benjamin Van Doren The Cornell Lab Mar 09, 2012

Expect a progression of good migration conditions very similar to last week’s. Conditions for bird migration will be favorable east of the Rockies and on the Great Plains over the weekend. By Monday and Tuesday these conditions make for good migration in the Midwest and by the middle and latter half of next week, warm conditions and southerly flow with set up good conditions for the East Coast. Intermittent precipitation will complicate things, but could create some waterfowl fallouts. Watch also for a Pacific Northwest storms to bring good seawatching as well.

This weekend’s weather will feature a large high pressure system setting up off the east coast with another unseasonably mild southerly flow developing from the Plains to the east coast over the course of next week. Return flow moisture around this large high pressure system will lead to precipitation spreading into the southern and central Plains. Meanwhile storminess will be the rule for the Pacific Northwest with relatively tranquil weather in the southwest U.S. and California. Monday through Friday will feature continued mild weather in much of the lower 48 states with frequent southerly winds while storm after storm hits the Pacific Northwest with bouts of precipitation.

Expect an early influx of Tree Swallows throughout much of the US with the week's warmer weather

Expect an early influx of Tree Swallows throughout much of the US with the week’s warmer weather

Conditions will not be favorable for much movement in the eastern US this weekend, but the departure of high pressure off the coast and return of southerly flow in its wake should bring increasingly favorable conditions by the middle to the end of the week, when migration magnitudes seen in the central US should also occur in the East. Widely scattered precipitation may shut down movements in many areas by very late in the week, depending on the extent and intensity of precipitation. Light winds across much of the interior western US should allow for light to moderate migration in the coming week, including across southern California, the desert Southwest, and the Four Corners region by the middle and end of the week. An unsettled weather pattern along the West Coast should bring early landbird migrants to the region, and make for good seawatching conditions in the wake of a cold front Sunday and Monday, especially in coastal Oregon and Washington.

These map show where warmer than average (oranges to red) and colder than average (blues) temperatures are projected in the next 8 to 10 days over the Northern Hemisphere. The map on the left is from the European Model and the right map is the Global Forecast System Model from NOAA. Image courtesy of the Pennsylvania State University Meteorology Department.

These map show where warmer than average (oranges to red) and colder than average (blues) temperatures are projected in the next 8 to 10 days over the Northern Hemisphere. The map on the left is from the European Model and the right map is the Global Forecast System Model from NOAA. Image courtesy of the Pennsylvania State University Meteorology Department.

Tree Swallows

An advancing front of Tree Swallows is surging up from the south and can be expected to sweep into new areas across much of the country this week. A sign of the unseasonably warm winter and early spring, we predict this year’s Tree Swallow arrival to be 5-10 days earlier than normal in most areas east of the Rockies. Already common along the Pacific slope from southern California to southern British Columbia, Tree Swallows have also shown the beginnings of a strong arrival in the mid-Atlantic, Pennsylvania, the southern Ohio River Valley, and southern Great Plains. With favorable migration conditions fueling the northward movement, this week we expect Tree Swallows will fill in most of their eastern breeding range south of Canada (except for the Canadian border states and northern Great Plains). Extremely early pioneers have already been seen in Wisconsin, Ontario, New York, and Massachusetts. We challenge birders in Nevada, Colorado, Nebraska, Minnesota, Michigan, Vermont, New Hampshire, and Maine to get out and find the first arriving Tree Swallow of the year; look for them to appear on the Rocky Mountain Front Range this weekend, on the Great Plains on Monday and Tuesday, and in northern New England by late next week.

Other species that are likely to move along with the Tree Swallows are Eastern Phoebes, Eastern and Western Meadowlarks, and Wilson’s Snipe. Watch for the earliest Northern Rough-winged and Barn Swallows in the mid-continent as well.

Regional Forecasts


  • Tree Swallows will continue to advance up the West Coast, with the influx likely pushing into British Columbia. Violet-green Swallows will also be in evidence, occurring more broadly across the region.
  • Common Black-Hawks should return to breeding locales in southeastern Arizona. Also watch for migrants overhead or along riparian strips. There have already been reports from Tubac and Sweetwater Wetlands. The Arizona frequency chart shows the quick return of this species quite well.
  • Expect Rufous Hummingbirds numbers to continue to build along the West Coast with the first arrivals in British Columbia likely this week.
  • The first few Pacific-slope Flycatchers should begin to appear by weeks’ end, especially in California.
  • Strong west winds along the coast on Monday should push migrating loons and Black-legged Kittiwakes near shore.

Great Plains

  • Goose and duck migration should continue in full swing throughout the region. Observers in northern regions should watch for a continuing influx of early waterfowl, particularly geese, Northern Pintail, and American Wigeon.
  • This should be an excellent week to carefully scrutinize flocks of gulls as they continue their northward migration. Gull diversity is often at its best in mid-March, particularly along the Front Range of Colorado. Look for Glaucous, Iceland, Thayer’s, and Lesser Black-backed, among the more numerous American Herring Gulls. These should be joined by the first waves of Franklin’s Gulls.
  • Oklahoma and Kansas should see the first significant influx of migrant shorebirds that should include good numbers of Greater Yellowlegs, Baird’s Sandpiper, Pectoral Sandpiper, American Golden-Plover, and American Avocet.
  • Raptors should be on the move across the northern Great Plains, with Red-tailed Hawk, Rough-legged Hawk, and Bald Eagle dominating the mix.

Upper Midwest and Northeast

  • Expect Tree Swallows to arrive in good numbers in all but the most northerly portions of this region. Expect the vanguard of the Eastern Phoebe movement to appear this week, with a good push occurring late in the week.
  • Watch for migrant Rough-legged Hawk and Golden Eagle. Both species should be nearing their peak migration periods for returning adults, and it would be worth spending an hour or two scanning the skies, even if you live in residential areas where these species may be rarely detected. If possible, try to photograph Golden Eagles to help document the changing status of this species in the East.
  • American Woodcocks have returned to many breeding grounds. Pick a quiet and warm evening to check likely habitat where old fields and woodlands mix. Listen for this species’ distinctive peenting and wild aerial displays. Check the March American Woodcock  eBird map first and see if you can find a few locales where the species hasn’t been previously reported. Return to old sites to see if this declining species has returned. Remember, it’s just as important to submit checklists from where you don’t find them.

Gulf Coast and Southeast

  • The first migrant warblers should begin to make landfall along the Gulf Coast, including Louisiana Waterthrush and Prothonotary Warbler.
  • Watch and listen for Chuck-will’s-widow in Florida where the species should arrive in strong numbers. If the southerly flow continues, also expect the first Chuck-will’s-widows to be detected in Georgia, but don’t expect the first in Louisiana or Texas until early April.
  • Expect most large flocks of wintering waterfowl, particularly diving ducks and Northern Pintail, to depart and be replaced by growing numbers of Blue-winged Teal. Since many species of waterfowl are on the move, it is worth carefully checking water bodies daily or even more often.


BirdCast is a project of NOAA and the Cornell Lab of Ornithology that will be studying bird migration and weather, using eBird data in conjunction with NOAA weather forecasts and novel computer modeling techniques. In Spring 2012 BirdCast will publish periodic forecasts discussing and predicting bird migration. Your observations from before and after these events will be be used to develop better predictive models relating to birds and weather. Hopefully BirdCast will provide useful alerts about the best birding days in your area and heighten general awareness about the connection between bird migration and weather.

As always, we encourage you to get out both before and after the weather event, report your birds to eBird, and let us know what you see on our Facebook page by commenting under the BirdCast story. Please include links to your eBird checklists that we can cite in next week’s summary (just copy the URL of the checklist and paste it in).

Special thanks to David Nicosia, our partner at NOAA, for the weather maps and analysis.