Dispersal and dispersion of black-tailed deer: models and observations [Odocoileus hemionus, Canada]

• Published in: Journal of mammalogy 1983-01, Vol.64 (2), p.201-209
• Main Authors: Bunnell, F. L., Harestad, A. S.
• Format: Article
• Language: English
• Subjects: Deer; Fawns; Female animals; Male animals; Mammalogy; Mammals; Mating behavior; Modeling; Odocoileus hemionus columbianus; Random walk; Yearlings
• ISSN: 0022-2372; 1545-1542; 1545-1542; 0022-2372
• DOI: 10.2307/1380549

The term dispersal is used to include individual movements out of an area larger than a home range that exhibit no predictable return; many models examining dispersal incorporate time explicitly. Dispersion is defined as the distribution of animals in space, ignoring time since birth. Direction, distance, and age at dispersal were examined for Odocoileus hemionus columbianus on Vancouver Island, B. C., and in western Washington. Empirically, movements >5 km were dispersive. Dispersive movements showed significant directionality as a function of topography; non-dispersive movements showed none. Dispersive movements averaged 15.2 ± 5.1 and 12.2 ± 1.7 km for males and females, respectively; comparable values for non-dispersive movements were 1.8 ± 0.3 and 1.7 ± 0.4 km. Movements greater than 12 km were rare (5 to 10%) and generally were made by males. Dispersal was greatest at 1-2 years of age. The sex and age distribution of dispersing individuals suggested that increased access to mates could explain observed patterns. When models were compared statistically with observations, the latter showed neither attributes of a random walk or diffusion process nor normal distribution about birth sites. Observed patterns suggest two phenotypes-"non-dispersers" and "dispersers."