82 Tachycineta thalassina Oct. 20 El Batel, 5100 feet, Sinaloa A large, widely spread flock, of at least 75 individuals, was observed feeding over the cleared areas north of the pass. Appa- rently a migrating flock, after a half hour or so, they left the area. No other swallows have been seen, but Leopold reported a flock several days ago of another species not identified with certainty.