Migration Report: 9 – 15 March 2012

Benjamin Van Doren The Cornell Lab Mar 16, 2012

Refresh your memory with last week’s BirdCast, then read on to see how we did.

There was light migration in the mid-continent over the weekend, but building high pressure caused some very large nights of migration by mid-week on 13-14 March and 14-15 March. The radar imagery displayed here corroborated the arrivals of birds seen on the ground by observers across much of the country. Various frontal boundaries and areas of precipitation interfered with migration at both the local and continental scales, especially apparent on the map for 16 March. Last week’s BirdCast Forecast predicted a widespread arrival of Tree Swallows and Eastern Phoebes (both much earlier than usual), along with other species. Did BirdCast get it right? Read on to find out.

Migration was light and localized overnight 10-11 March, with light migration in the southern Appalachians and Southwestern US, while there were favorable conditions only in portions of the upper Mississippi Valley. Light migration was apparent and in the far southwestern US. The following night saw similar conditions move eastward, with light scattered migration in the East south of the eastern Great Lakes and behind a stalled front in Texas. As high pressure began to build into the southern Plains on 12-13 March, there was significant movement through Texas and the southern Great Plains, and in the Midwest nearly as far north as the Ohio River Valley. Monday and Tuesday saw the best bird arrivals in New England as well. This trend continued and migration ramped up significantly on Tuesday and Wednesday nights (13-14 March and 14-15 March), with widespread movement everywhere east of the Rockies on those nights, and resultant arrivals seen the following morning. Birds were primarily associated with a warm front expanding east into the Great Lakes, with southerly flow pervasive across regions to the south of the frontal boundary. To the east of this boundary, where cold air still prevailed, migration was minimal at best (this is most apparent on the 15 March map in the below animation, which shows the sharp division at the cold front crossing Pennsylvania and New Jersey). By Thursday night, migration was still evident to the south of a frontal boundary stalled from the central Plains across the eastern Great Lakes to the mid-Atlantic, with the exception of areas with precipitation in the Mississippi valley and eastern Great Lakes. In the warm and calm conditions of the southeast, some larger movements occurred.

Throughout the forecast period, conditions in the western US remained relatively unfavorable for extensive migration to occur, although several nights of light migration are apparent in the radar images in the Southwest.

This week’s radar imagery–showing bird migration in action–is available as an animation. Be sure to read our feature on using radar to understand bird migration to get the most out of these maps. We were probably a bit late in last week’s predictions, since the better bird movements were Monday-Tuesday and Tuesday-Wednesday.

Below are observations from the eBird community, many of which bear out last week’s predictions:

  • The predicted coastal storm in the Pacific Northwest indeed produced great seawatching, and notable forced some Red Phalaropes to shore. Here is a checklist from Oregon by Deb Holland  with some displaced phalaropes.
  • On South Padre Island, Texas, Sam Galick, Doug Gochfeld, and Scott Whittle found a Golden-cheeked Warbler on 9 March. His checklist is rich with photos–including a locally rare Field Sparrow–and will make many of us jealous! Leave it to the Cape May morning flight counter to pick out the flyover Golden-cheeked! Sam’s own words capture the excitement and weather conditions the best: “In talking to locals, this constitutes the first documented record not only for the island but most likely Cameron County. The bird’s occurrence followed two days of 20-30 mph sustained NW winds (sometimes gusting to 45mph+) after a strong cold front blew past that day. The bird flew high over our heads dropping in a mesquite bush in front of us. I had trouble in my excitement to spill out the words GOLDEN-CHEEKED WARBLER!!! It remained through 4PM for some local birders to witness after word was spread through email. It was not seen the next day.”
  • The Great Plains and western Great Lakes continue to see large waterfowl numbers. Two species surging back are Franklin’s Gull, which shows a very cool linear flight line from western South American and a push well north on the Great Plains this week. The eBird map for March 2012 shows that surge, and we predict the big pulse will happen next week. American White Pelicans similarly show an early influx ( March 2012 eBird map), with a record-early eBird observation in Manitoba this week from Richard Staniforth.
  • In New England, Ospreys, Tree Swallows and Eastern Phoebes arrived across a broad front from Sunday to Tuesday. Within the eBird line graphs feature, it is possible to look at daily frequency for a single month and to compare the last 5 years to see if any year is significantly early. Here are the March line graphs for southern and northern New England for Osprey ( southnorth), Tree Swallow (southnorth), and Eastern Phoebe ( southnorth). Based on this Ospreys are a few days early in the south but have yet to be reported in the north (not surprisingly); Tree Swallows have reached 4% frequency in the south about 6 days earlier than the last two years and 10-13 days earlier than in 2008 or 2009; they have even reached northern New England, with reports on multiple checklists 13-15 March exceeding 2008-2009 arrivals by two weeks and 2010-2011 arrivals by 4-7 days (only 2011 has an earlier record); Eastern Phoebe is perhaps most striking. In southern New England, they showed their first signs of arrival on 12 March and a strong arrival 13-14 March, reaching 10% frequency on 15 March! By comparison, the second-earliest phoebe year was 2010, which first exceeded 10% on 21 March which itself was a week earlier than 2008, 2009, or 2011.
  • At Cape May, New Jersey, Tom Reed reported a cool morning of migration 14 March, including an impressive fight of Pine Warblers, not usually a species noted for obvious, diurnal migration. Perhaps of even more interest are his comments on possible House Finch migration, a species that typically migrates “under the radar”.
  • Another species that is often referred to as resident, but is clearly quite migratory, is Northern Mockingbird. Its migratory tendencies can be seen by comparing winter and summer maps in eBird, but only rarely is their migration actually observed or commented upon, especially in the East. A widespread resident in the Northeastern U.S., we implore eBirders to think about mockingbird movements this year and next spring, to try to better understand their migration. In the Boston area, Marshall Iliff’s regular checks of his local patch revealed three “new” Northern Mockingbirds on territory 12 March 2012. See full commentary on the12 March checklist or check out the line graphs (check abundance and high count especially) for his “patch”, which show occasional wintering but a clear arrival in March. In keeping with the theme, this year’s arrival was 2 weeks early. We would love to hear other stories of Northern Mockingbird movements (post them to  Facebook please)!

As we compile the weekly summaries, it is really helpful to hear from all of you for what you are seeing, and what patterns to look for. Please let us know what you are seeing, especially if you are in the Rocky Mountains, on the Great Plains, or in the Midwest! Facebook is the best place to share your news, so just comment under this story on our Wall.

Posted 16 March 2012 by Marshall Iliff, Christopher Wood, and Brian Sullivan of the Cornell Lab of Ornithology on behalf of Team eBird and BirdCast. Special thanks to David Nicosia, our partner at NOAA, for the weather maps and analysis in our BirdCast predictions.