Naturalist Newsletter of March 10, 2008
written in the community of 28 de Junio, in the Central Valley,
8 kms east of Pujiltic, Chiapas, MÉXICO
about 800 meters in elevation, ± LAT. 16° 18'N, LONG. -92° 28'W.
Here any day you can see Tree Swallows swooping about, sometimes 15 or 20 in a disperse flock and sometimes excitedly calling to one another chrip, chrip, chrip...
This week, and not previously since I've been here, about an hour before dusk the Tree Swallows' usual last-minute foraging was augmented by large numbers of Barn Swallows. At any one time you might see ten to twenty Barn Swallows occasionally swooping for bugs but in general they're all heading toward the west.
Is this spring migration? Barn Swallows are only winter visitors here, overwintering from central Mexico to the southern tip of South America. Flying westward here means flying up Chipas's Central Valley to where it's not far from the Pacific coast. Are these birds following the coast to California?
Howell writes: "Winter movements need study." So maybe these notes will someday help someone figure out how our pre-dusk flights fit into the broader scheme of things.