DIET AND FORAGING BEHAVIOR OF VAUXS SWIFTS IN NORTHEASTERN OREGON

The diet of Vaux's Swifts (Chaetura vauxi) during the breeding season consisted primarily of insects in the orders Homoptera (hoppers, aphid s, whiteflies), Diptera (flies), Ephemeroptera (mayflies), and Hymenop tera (ants, parasitic wasps). Diet was determined from 223 food boluse s collected from adults feeding nestlings and represented 24,133 indiv idual insects and spiders. Diet did not differ among five study areas or by time of day. A pair of swifts feeds an average of 5,344 arthropo ds to their nestlings each day, and an average of 154,976 arthropods d uring the nestling growth period. Radio-tagged swifts foraged up to 5. 4 km from the nest. Of actual sightings of radio-tagged birds. 64% wer e foraging over land, 27% were foraging over water, and 9% were travel ing in a straight line.