A multi-scale behavioural approach to understanding the movements of woodland caribou
Dates
Year
2001
Citation
Johnson, Chris Jack, 2001, A multi-scale behavioural approach to understanding the movements of woodland caribou: University of Northern British Columbia (Canada).
Summary
To conserve woodland caribou, resource managers and biologists must understand the processes governing movements and distribution of those animals. I employed a scale-explicit approach to understand some of the mechanisms influencing caribou behaviour. I trailed caribou in forested and alpine habitats and recorded attributes of feeding sites and patches. At larger scales, I used GPS collars to record the movements of caribou. At the scale of the feeding site, caribou cratered at locations with lower snow depths and greater amounts of a variety of terrestrial lichen species. Following increases in snow depth, hardness, and density, caribou in the forest fed more frequently at trees with abundant arboreal lichens. Foraging effort at [...]
Summary
To conserve woodland caribou, resource managers and biologists must understand the processes governing movements and distribution of those animals. I employed a scale-explicit approach to understand some of the mechanisms influencing caribou behaviour. I trailed caribou in forested and alpine habitats and recorded attributes of feeding sites and patches. At larger scales, I used GPS collars to record the movements of caribou. At the scale of the feeding site, caribou cratered at locations with lower snow depths and greater amounts of a variety of terrestrial lichen species. Following increases in snow depth, hardness, and density, caribou in the forest fed more frequently at trees with abundant arboreal lichens. Foraging effort at patches was positively related to two species of terrestrial lichen and decreasing snow depth. In the alpine, no relationship existed between patch selection and abundance of terrestrial lichens or snow conditions. The incongruity between variables important at the feeding site and those important at the patch indicated that foraging decisions of caribou were affected by spatial scale. I converted intervals between GPS locations to movement rates, and used a two-process model to identify the break point between large-scale, inter-patch and small-scale, intra-patch movements. Using those scale criteria, I tested the influence of correlated behaviours, cover type, predation risk, energetic costs of movement, and patch configuration on three scales of selection by caribou: intra-patch, inter-patch, and general habitats (forest, alpine, forest-alpine). Pine-lichen woodlands and wind-swept rocky slopes were the most important cover types selected by caribou at all scales in the forest and alpine, respectively. A lower energetic cost of movement, and selection for lakes and rivers, suggested that during inter-patch movements, caribou often chose routes along valley bottoms. Selection of general habitats was more strongly related to composition than configuration of cover types. Predation risk had no effect at the scale of intra-patch movements, was the greatest for caribou making inter-patch movements, and was lowest for caribou in alpine habitats. Forest managers should maintain large patches of widely distributed pine-lichen woodlands, recognise the limiting effects of deep snow, and employ silvicultural strategies that minimise early seral-stage forests adjacent to caribou movement routes.