Growth and Dispersal of an Erupting Large Herbivore Population in Northern Canada: The Mackenzie Wood Bison (<i>Bison bison athabascae</i>)

Abstract

In 1973, 18 wood bison (Bison bison athabascae) were introduced to the Mackenzie Bison Sanctuary. The population has grown at a mean exponential rate of r = 0.215 ± 0.007, reaching 1718 bison >= 10 months of age by April 1987. Analysis of annual population growth revealed a maximum exponential rate of r = 0.267 in 1975, followed by a declining rate, reaching a low value of r = 0.013 in 1987. Selection predation on calves was proposed as a mechanism to explain the declining rate of population growth. The area occupied by the population increased at an exponential rate of 0.228 ± 0.017 sq km/yr. The dispersal of mature males followed a pattern described as an innate process, while dispersal of females and juveniles exhibited characteristics of pressure-threshold dispersal.