Colonization of Non-Traditional Range in Dispersing Elk, Cervus elaphus nelsoni, Populations


  • Fred Van Dyke Montana Department of Fish, Wildlife and Parks, Red Lodge, Montana 59068



Elk, Cervus elaphus, dispersal, habitat use, population, Montana


As ungulate populations increase in density on traditional range, resulting increases in intraspecific competition can encourage dispersal of some individuals to new areas. Such areas, although lower in density of conspecifics, might present unfamiliar arrays and types of habitat that could require altered patterns of home range and habitat use by dispersers. However, the specific adaptations employed by dispersers in such circumstances are not well documented or understood. I investigated three cases of range expansion by Elk (Cervus elaphus nelsoni) populations experiencing population growth on traditional ranges in south-central Montana, USA. Each source population produced a group that dispersed to non-traditional areas. Compared to source populations, dispersing groups increased average size of home ranges, changed patterns of use in core areas of home ranges, and used habitats differently than Elk on traditional range. Dispersing groups demonstrated fidelity to new ranges equal to that of source populations, but their seasonal tenure on non-traditional range was strongly linked to environmental conditions, especially rainfall. Dispersal of groups increased the overall range of the population and its range of habitat use. In growing populations of Elk, managers should determine if dispersing groups exist and whether they should be protected to establish new populations in marginal areas or be reduced to limit potential Elk-landowner conflicts.