Snake predation of bird eggs and nestlings is well documented (e.g., Best 1974, Skutch 1976, 1999, Nolan 1978, Finch 1981, Facimore and Fretwell 1980, Rodriguez-Robles 2002), and there are accounts of adult birds being killed by snakes, particularly rat snakes (Elaphe spp.) and Gopher Snakes (Pituophis catenifer), at nest sites (e.g., Blem 1979, Joern and Jackson 1983, Brown and Brown 1996, Stake 2001). Away from nests, rattlesnakes (Crotalus spp.) reportedly have preyed on adult birds ranging in size from the Field Sparrow (Spizella arborea; in Best 1974) to the Northern Bobwhite (Colinus virginianus; Bendire 1895), but more unusual are observations of nonvenomous snakes capturing birds older than fledglings. Skutch (1989) rescued a female Scarlet-rumped Tanager (Ramphocelus passerinii) from the jaws of a 1-m-long unidentified green snake in Costa Rica, and here I report attempts at predation on four passerines and two hummingbirds by the Sonoran Whipsnake (Masticophis bilineatus). Agile and capable of very rapid movement, this frequently arboreal serpent generally inhabits riparian woodlands, rocky bajadas, and madrean woodland in southeastern Arizona (Bezy and Enderson 2003) and southwestern New Mexico (pers. obs); its range in Mexico extends south in canyons and on mountain slopes to Oaxaca. All encounters were at the Bioresearch Ranch (TBR) headquarters, within the Central Peloncillo Research Natural Area, 12 km southeast of Rodeo, Hidalgo County (31° 50' N, 109° 01' W), in the madrean archipelago of mountains in far southwestern New Mexico. The surrounding vegetation consists primarily of madrean evergreen woodland (Brown 1994) at an elevation of 1648 m. A feeding station at the headquarters generally attracts large numbers of birds, and the observed whipsnake attacks occurred near feeders. Following is a brief account of these encounters.