Journal of Wildlife Management

Understanding spatiotemporal variability in prey accessibility is important for disentangling predator-prey interactions and is relevant to management interventions to reduce predation. Recently, caribou (Rangifer tarandus) in Newfoundland declined by 66%, with calf predation by black bears (Ursus americanus) implicated as a major proximate mechanism of the decline. Most predation occurs when calves are aggregated on calving grounds.

The authors evaluated properties of the Petersen mark-resight technique for estimating the population size of 6 woodland caribou (Rangifer tarandus) herds in Newfoundland. The authors' objective was to determine the robustness and efficiency of a novel marking technique for estimating population size of caribou where sightability bias is marginal. We marked caribou with pressurized oil-alkyde paint applied from a helicopter. Resighting surveys were conducted 2-3 weeks later. Data from 15 radiocollared animals indicated populations were closed and marks were not lost.

In many vertebrates size is one of the most influential and variable individual characteristics and a strong determinant of reproductive success. Body size is generally density dependent and decreases when intraspecific competition increases. Frequent and long distance movements increase energy expenditures and, therefore, may also influence body size, particularly in highly mobile species.