Video identification of predators at Golden-cheeked Warbler nests

We monitored 67 Golden-cheeked Warbler (Dendroica chrysoparia) nests with infrared video cameras and time-lapse recorders to identify predators. Rat snakes (Elaphe spp.) were the most frequent predators, depredating 12 nests and capturing three adult females. A variety of avian predators depredated seven nests, including three American Crows (Corvus brachyrynchos), two Brown-headed Cowbirds (Molothrus ater), one Western Scrub-Jay (Aphelocoma californica), and one Cooper's Hawk (Accipiter cooperii). Fox squirrels (Sciurus niger) depredated four nests and were the only mammalian predators recorded. Post-outcome recordings (i.e., after young fledged or nests failed) revealed western coachwhips (Masticophis flagellum testaceus), mice (Peromyscus sp.), and Greater Roadrunners (Geococcyx californianus) as potential predators, though they were not recorded at active nests. Video proved to be an effective method of monitoring Golden-cheeked Warbler nests, because all but one predator was identified and only two nests (3%) were abandoned.