Movement parameters of ungulates and scale-specific

• Main Author: Michael P. Gillingham
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: caribou; Rangifer tarandus
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.331.6544; http://web.unbc.ca/~johnsoch/Publications/Johnson et al. 2002 Movement parameters of ungulates.pdf

1. Most studies of animal movements and habitat selection do not recognize empirically that different components of the environment are important to animals at different scales. Often, availability of habitats is defined at one or more arbitrary spatio-temporal scales, but use of those habitats is constrained to one scale. Identification of scalar movement is the first step in developing models to explain why animals select or move to certain parts of their range. We used a non-linear curve-fitting model of movement rates to identify discontinuities in the scales of movement by woodland caribou Rangifer tarandus caribou collared with global positioning system (GPS) collars. 2. We differentiated intrapatch from interpatch movements, but were unable to distinguish interpatch from migratory-type movements for most combinations of individual caribou by season. Model fit was stronger for winter than summer movements. We suggest that increased patch heterogeneity during the winter resulted in interseason variation in movements and corresponding model fit. 3. Responses by caribou to the environment were scale-dependent. When we applied logistic regressions, land-cover type, energetic costs of movement, and predation risk differentiated the two scales of movement. Intrapatch movements had a lower cost of movement, were associated with cover types where foraging behaviours probably occurred, and were closer to areas of higher predator risk than interpatch movements. 4. Application of the non-linear model will aid in developing mechanism-based approaches to studying resource selection and animal behaviour. Key-words: caribou, GPS, habitat patch, heterogeneity, predation risk.