Prey or predator? Body size of an approaching animal affects decisions to attack or escape

摘要: An animal must assess an approaching heterospecific to determine whether it is prey or predator. Because tend be smaller than their predators, foraging responses decrease and escape are predicted increase over a range of approacher size. Sufficiently, small approachers may readily identified as large ones predators. However, more time closer approach required intermediate size, leading predictions that predator/prey evaluations differ among individuals, attacks on the begin from shorter distances for begins at distance larger approachers. In field experiment, we dragged tethered model orthopterans 3 sizes toward 2 lizard species in body As size increased, lizards were likely flee had longer flight initiation distance. decreased, advance bite models began advances distances. At some individuals fled others attacked models. Sceloporus jarrovii, species, was attack less S. virgatus The prediction optimal theory increases with predator due greater risk verified. Our evidence indicates increases, successive transitions occur between rapid assessment prey, uncertainty requiring inspection, identification potential Key words: behavior, distance, Squamata. [Behav Ecol]