Oddity and Specific Searching Image more Important than Conspicuousness in Prey Selection

Abstract

IN an earlier report¹ I presented results from a pilot experiment which suggested that conspicuousness of prey was the most important determinant in prey selection. I now have results from 1,600 laboratory experiments performed with two species of hawks in rigorous experimental conditions, which suggest that oddity and the specific searching image are more important. Many observations and experimental results fit well into the generalization that predators have a tendency to select odd prey, animals that differ in some way from most prey^2,3, although unequivocal evidence is lacking. Predators also show a tendency to continue to select a given type of prey, even though other types may be as readily, or even more easily available, a phenomenon that L. Tinbergen⁴ has termed the “specific searching image”. My experiments are a simultaneous test of three factors which influence prey selection: conspicuousness, oddity, and the specific searching image.