March 25, 2009
Dr. David Aborn

Dear Students:

It was another pretty good week for migration. Those couple of days of southerly winds brought in another batch of migrants. Along the Gulf coast from Texas to Alabama, people were reporting lots of Blue-gray Gnatcatchers, as well as Yellow-throated Warblers, Black-and-white Warblers, Northern Parulas, Common Yellowthroats, White-eyed Vireos, and the first Great-crested Flycatcher of the season. Here in the southeastern US, the first Louisiana Waterthrushes and Blue-headed Vireos were seen (one of the vireos was in my back yard on Saturday!). The southerly winds allowed some of those birds to make it fairly far north. Tree Swallows, Barn Swallows, Louisiana Waterthrushes and Blue-headed Vireos were all seen in Ohio, Missouri, West Virginia, and Washington, DC.

Things were similar out west. Birders in New Mexico, Arizona, and California all reported the first Bell's Vireos and Ash-throated Flycatchers, along with Western Kingbirds, Wilson's Warblers, Yellow Warblers, Lucy's Warblers, Bullock's Orioles, Violet-green Swallows, and Rufus Hummingbirds. As in the east, the southerly winds allowed many migrants to fly pretty far north. One birder near Tacoma, Washington reported over 300 Violet-green and Northern Rough-winged Swallows, and had 10 Rufus Hummingbirds at his feeders!

What to Expect This Week
This week's weather map is a little complicated. Take a look:

  • Right now, a cold front is bringing heavy rain to the central US and Texas. That, along with northerly winds behind the front, will prevent migrants from flying for the next couple of days.
  • As that front moves east, it is expected to stall, which will bring rainy weather to the southeastern US for the next few days. They are forecasting rain here in Tennessee Wednesday through Saturday.
  • While the rain is predicted to end a couple of days earlier in the Northeast, it will be turning colder. All of this means birds will really be grounded for a while.
  • With the increase in migration we are seeing, this prolonged spell of bad weather could result in the first fallouts of the season. Many birds arriving from the tropics are exhausted. (It takes about 18 hours non-stop for a bird to fly across the Gulf of Mexico!) If they encounter rain or headwinds, it is more than they can handle and they land very quickly and in large numbers. To someone on the ground, it looks like the birds are "falling out" of the sky, hence the name of the phenomenon. A fallout is a very impressive sight to see.
  • In the western US, another front is moving into the Northwest. All those swallows near Tacoma will be staying a while. The Southwest, however, will remain warm and dry, so people can expect more waves of migrants to come in.

It looks like migration is well underway, with lots more to come. Get out there and enjoy it!

Take Care.

David Aborn
North Chickamauga Creek Conservancy
Chattanooga, TN