Variation in Vigilance in White-tailed Deer (Odocoileus virginianus) in Northeastern Kansas

—This study was designed to test hypotheses regarding vigilance (a state of alertness that allows an animal to detect the presence of predators or other threats) in whitetailed deer (Odocoileus virginianus). Based on findings on other species, we predicted that: (1) increasing group size would result in decreased individual vigilance; (2) juveniles would be less vigilant than adults; and (3) males would be less vigilant than females. Deer were observed from a tower in northeastern Kansas from May through Jul. 2001 at dawn and dusk. In accordance with other species, individual vigilance was negatively correlated with group size and juveniles spent less time vigilant than adults. However, there was no apparent difference in vigilance levels between the sexes in adults. We conclude that deer exploit loose aggregations to maximize foraging time by decreasing individual vigilance (without increasing risk) and that the trade off between vigilance and foraging intensity changes with maturation.