Enemy recognition by field sparrows

摘要

I examined enemy recognition in Field Sparrows (Spizella pusilla) using models of a brood parasite (Brown-headed Cowbird, Molothrus ater), an avian nest predator (Blue Jay, Cyanocitta cristata), and a nonthreatening control (Fox Sparrow, Passerina iliaca) during two period of the nesting cycle: the first three days of incubation and when chicks were 2-3 d old. As predicted, Field Sparrows responded more frequently to the predator model than to the control model during both periods, and gave stronger responses to the predator model (as measured by the number of "chip" calls) during the nestling period than during incubation.