The Degree of Mutual Resemblance and its Effect on Predation in Young Birds

Abstract

AbstractWe presented sets of naive common quails with 6 different sequences of three species of aposematic insects: Cercopis intermedia, Caenocoris nerii, and Eurydema decoratum. All three species had a similar body plan but different marking patterns. Our goal was to determine whether naive predators initially form a sharpely defined image which would stimulate an aversive reaction only in the presence of that signal. In contrast to the discrimination shown by adults of another avian species (SILLÉN‐TULLBERG et al. 1982), these birds usually generalized the warning signals and rejected later, somewhat different, noxious prey after an unpleasant experience. The likelihood of attack declined from 100% with the initial offering of the first species to 37.5% at the first presentation of the second species to 20.8% with the initial offering of the third prey type. We found that overall contact with the aposematic prey decreased significantly (chi‐square test, p < .005) and that eating the test prey ceased completely. Young predators and different predatory species may be less discerning within certain limits or may require a longer time to learn to make fine distinctions than other classes of predators. The processes of generalization may involve stimulus filtration and aides memoires.