Demographic Differences Between an Old and a New Colony of Black-tailed Prairie Dogs (Cynomys ludovicianus)

Abstract
Two colonies of black-tailed prairie dogs (G. ludovicianus) in Wind Cave Natinal Park, South Dakota [USA], were compared during 1979 and 1980 to investigate the effects of the age of the population and the availability of resources on specific demographic parameters. The older colony had little available habitat for expansion. At the younger colony there was a greater proportion of successful pregnancies, the litters were larger, the juveniles grew faster, yearlings were more likely to reproduce, survivorship of adults and juveniles was greater and the density was > 2 times that of the older colony. Individuals at the younger colony showed a distinct feeding preference for vegetation growing at the colony periphery. Because this peripheral vegetation had onlyrecently been modified from surplus habitat, surplus habitat available to the younger colony accounted for the observed demographic differences.