Weather and Songbird Migration: April 25, 2012
Dr. David Aborn, ornithologist
Dr. David Aborn

Dear Students:

Migration is definitely peaking, and more birds are on the way! At the end of last week, southerly winds allowed many migrants to make some good progress north, but by the weekend, that powerful storm system stopped them dead in their tracks.

This weekend I participated in the annual BioBlitz at the Chattanooga Nature Center. A BioBlitz is an intensive 24-hour survey of all the biodiversity in the area, and I have always been in charge of the bird surveys. We found a good number of bird species, including many Wood Thrushes and Kentucky Warblers, as well as the first Indigo Buntings (lots), Ovenbirds, and Tennessee Warblers of the season. There was even a Bank Swallow, which is an uncommon visitor to the area. Indigo Buntings were also seen in New York and Illinois, along with Tennessee Warblers, Rose-breasted Grosbeaks, and Yellow Warblers. The first Gray Catbirds, Baltimore Orioles, Eastern Kingbirds, and Swainson's Thrushes arrived in Indiana, and the southerly winds helped push Blue-headed Vireos into Michigan and Indigo Buntings, Barns Swallows, Tree Swallows, and Scarlet Tanagers as far as Minnesota!

Sunday and Monday (April 22-23), everything changed with the passage of that storm system. It brought rain and very strong north winds to the eastern half of the country, especially the east coast. As the low pressure area moved up the coast, some migrants that breed in the southern US got carried up with it. Many of the New England States and even the Canadian Maritimes reported good numbers of migrants typically found in the southern states, like Yellow-throated Warblers and Prothonotary Warblers. Those birds now have a Journey South ahead of them!

By Tuesday and Wednesday (April 24-25), the winds had shifted, and birds that were bottled up farther south have been able to head north again. At my study site this morning I saw my first Yellow-breasted Chats, and also some Indigo Buntings.

Migrating Birds Show on Radar Maps!
People along the Gulf coast should be ready, because birds that had been stuck in the tropics now have good tailwinds and are arriving, as the radar from this morning shows. The green and blue areas you see off the Texas and Louisiana coasts is not rain, those are flocks of migrating birds about to make landfall!

Radar map shows flocks of migrating birds about to make landfall. Radar map shows flocks of migrating birds about to make landfall.

Steady Stream of Migrants in the West
Out West, southerly winds have kept a steady stream of migrants moving all over. Vaux's Swifts, Rufus Hummingbirds, Nashville Warblers, and Yellow Warblers have arrived in Idaho, and birders in Oregon were treated to a nice assortment, including Hammond's Flycatchers, Cassin's Vireos, Warbling Vireos, Orange-crowned, Nashville, Townsend's, Black-throated-gray, and Wilson's Warblers.

What Can We Expect This Week?
This week looks good for migration.

  • A stationary front is over the middle of the country, but not much rain is associated with it, nor are the winds very strong. Thus migrants should have pretty good flying weather for at least the next several days.
  • All those birds about to arrive on the Gulf coast and new arrivals out west from Mexico should be able to make some good progress north, so birders all over the country should get ready!

Migration may be peaking, but there are still a few more weeks to go, so don't miss out on the fun!

Take Care.

David Aborn
North Chickamauga Creek Conservancy
Chattanooga, TN