Reactions of hand-reared and wild-caught predators toward warningly colored, gregarious, and conspicuous prey

Abstract

Recently there has been debate over the importance of innate avoidance of aposematic prey by predators, particularly birds. There is evidence that the predators have innate or unlearned, thus, inherited avoidance against certain colors, but whether there is any innate avoidance against gregariousness or conspicuousness is unclear. Previously predator behavior toward these characters of aposematic prey have been tested in separate experiments. We designed an experiment to separate inheritance toward color, gregariousness, and conspiucuosness. We simultaneously offered the predators warningly colored and nonwarningly colored prey items, both aggregated and solitary, on white (conspicuous) or brown (cryptic) backgrounds. The predators we used were naive (hand raised), wild-caught yearling and adult great tits (Parus major L.). The results confirm previous results regarding the innate avoidance of color. Naive predators seemed to have a genetically or culturally transmitted avoidance of yellow and black prey compared to brown prey. Surprisingly, yearling wild-caught great tits were more selective than adults, which did not show as strong avoidance of yellow and black prey. More importantly, birds did not find gregarious prey more aversive than single prey, which indicates that grouping alone does not serve as an innate avoidance signal. Conspicuousness itself was not aversive to the predators. Our results suggest that the avoidance against a particular color pattern probably has an inherited basis, whereas gregarious and conspicuous characters of prey presumably aid the avoidance learning.