The Antipredator Vigilance of Adult and Juvenile Thirteen‐lined Ground Squirrels (Sciuridae: Spermophilus tridecemlineatus): Visual Obstruction and Simulated Hawk Attacks

Abstract

AbstractVisual antipredator vigilance was predicted to increase in the presence of visual obstructions that do not otherwise provide cover. This hypothesis was tested using 13‐lined ground squirrels as they fed in four Plexiglas boxes that varied in the extent and location of visual obstruction. Adults and juveniles of both sexes were studied. Adults reacted to long‐range lateral visual occlusion and total occlusion by withdrawing more often and assuming both more pronounced and lengthy alert postures relative to short‐range lateral occlusion and no occlusion. Juveniles were less vigilant than adults and did not behave differently in the four treatment conditions. There were no sex differences. Simulated hawk attacks on squirrels feeding in the boxes indicate that the greater vigilance of adults led to significantly reduced reaction times compared with juveniles.