ABSTRACT
Redwing blackbirds (Agelaius phoeniceus, Mason & Reidinger, 1983a), European starlings (Sturnus vulgaris, Schuler, 1980), house sparrows (Passer domesticus; Greig-Smith & Rowney, 1987), and a variety of other avian species (e.g., Japanese quail, Corturnix japonica: Czaplicki, Borrebach, & Wilcoxin, 1976) learn to avoid visual cues associated with sickness. For redwings, visual stimuli appear relatively more important than taste in avoidence acquisition (Mason & Reidinger, 1983a), and certain colors seem to be more effective conditioned stimuli than others. For example, avoidance generalization is broad for hues of red, but relatively narrow for hues of green (Mason & Reidinger, 1983b). Ecologically, the differential effectiveness of color is predictable, since red is used frequently by animals to advertise unpalatability (aposematic coloration; Terhune, 1977). Green serves this function rarely, if ever, and is more often associated with the cryptic coloration used by palatable prey for concealment from predators (Brower, Cook, & Croze, 1967; Wickler, 1968).
