VIGILANCE IN NXAI-PAN SPRINGBOK, ANTIDORCAS-MARSUPIALIS

Vigilance rates were surveyed on juvenile and adult female springbok in 3 positions (close edge, center, and far edge) in herds of 17 to 536 springbok in Nxai Pan N.P., Botswana. Rates were generally low. They decreased as group size increased but were not lower when other grazers joined springbok herds. Edge animals spent roughly twice as much time vigilant as central animals. Juveniles were slightly less vigilant than adults but this may reflect greater movement. Surprisingly, springbok were more vigilant in late mornings than in early mornings or afternoons. Spring bok approaching tree clumps were more vigilant than matched individuals moving in the open. Preliminary data indicate that vigilance is higher at night than during the day and that territorial males have moderate to low levels of vigilance. In general, vigilance varied in ways expected to lower the risk of being taken by ambush predators such as leopards.