Weather and Songbird Migration: Spring 2009

Weather & Songbird Migration

April 1, 2009 *Dear Students:* Well, things are on the move! All that rain we had last week produced some of the first fallouts along the Gulf coast, and once the rain cleared Monday and yesterday, many birds either arrived from the tropics or, if they were already here, made their way north.
	Dr. David Aborn
The biggest fallout occurred along the Alabama coast. A bird bander working down there banded 1,000 birds over the weekend! Some people, myself included, have special permission from the US Fish and Wildlife Service to capture birds in soft nylon nets called mist nets.
We then put a small numbered aluminum band on one of the bird's legs, like an ID bracelet. This individual identification of birds makes possible studies of dispersal and migration, behavior and social structure, life-span and survival rate, reproductive success and population growth. When banded birds are captured, released alive and reported from somewhere else we can reconstruct the movements of the individual bird.	Magnolia Warbler in mist net
In this way we have learned that some species go south in one pathway and return north by another pathway. Some banders use colored leg bands to mark individual birds and study their local movements and behaviors from a distance. Individual identification of birds allows many things to be studied without handling the bird again. Some things that may be studied include territorial behavior, mate fidelity, territory size, and reproductive behavior (which bird builds the nest? Feeds the young? How often?).
Banding allows the determination of the minimum length of time that an individual bird lives. Without an individual marker, there would be no way to determine if the Cardinal that is outside my window is the same bird that I saw last year or not. I once captured an American Redstart here that someone else banded, and it turned out to be 8 years old (the record is 10 years), There is a record of a hummingbird living as long as 12 years!	Banding a Gray Catbird
Once the rain cleared out, there was a big influx of new arrivals. Yesterday on the Texas coast, birders reported large numbers of Rose-breasted Grosbeaks, Ruby-throated Hummingbirds, White-eyed Vireos, Common Yellowthroats, Gray Catbirds, and Orchard Orioles; and smaller numbers of Hooded Warblers, Black-throated-green Warblers, Nashville Warblers, and many other species. Species that had arrived previously took advantage of the good weather to continue their journey, with hundreds to thousands of Tree Swallows reported in Delaware, New York, and Ohio, and the first arrivals of Yellow-throated Warblers and Blue-gray Gnatcatchers in Illinois and Missouri. Out west, migration was slow but steady. There were no big fallouts, but there was a steady stream of flycatchers, warblers, vireos, and orioles in New Mexico, 4 species of warblers, especially Orange-crowned Warblers, in California, and Arizona saw its first Lazuli Bunting of the season.
What to Expect This Week
The weather continues to be active. Take a look:

There is a cold front that is pushing through the eastern US. The winds behind it are not very strong, but the rain will still force birds to land for a day.
When the weather clears they had better get moving quickly because there is another front moving in from the west. This one is stronger, with some good north
winds that will keep birds grounded.
The weather map does not show it, but weather forecasters are saying there will be yet another front moving in over the weekend. All this means that there could be some good birding, if the rain stops long enough for you to get out!
The rain and north winds will mean periods where there could be some more fallouts, and the few clear periods will mean birds will try to make it as far north as they can in a short time.

Migration is really cranking up, so be on the lookout for new birds to show up in your area! Take care.

Take Care.

David Aborn
North Chickamauga Creek Conservancy
Chattanooga, TN