Investigation of winter habitat selection by woodland caribou in relation to forage abundance and snow accumulation

摘要

Imprecision and misclassification of land cover types are two issues commonlyencountered in habitat selection studies using satellite land cover classifications andtelemetry data. Here, the utility of broad land cover types is explored in a study of habitatselection by woodland caribou (Rangifer tarandus caribou). Broad land cover types havepotential to reduce the misclassification error associated with finer land cover types,while remaining relevant to the factors influencing habitat selection in the species ofinterest. Lichen abundance and snow accumulation are two factors important inexplaining the selection of land cover types by woodland caribou in winter, and they areused here to predict the probability of occupation by caribou of land cover types in threeregions of the boreal forest in Eastern Canada. Land cover types were initiallycategorized using Landsat EOSD land cover data, and field surveys were conducted tomeasure terrestrial and arboreal lichen abundance in each land cover type. The relativeaccumulation of snow was modeled for land cover types using documented patterns ofsnow distribution in the boreal forest as well as data collected in the Greater Gros MorneEcosystem, Newfoundland, and the C?te-Nord region, Quebec. Subsequently, land covertypes were collapsed into three (dense forest, sparse-open forest, and non forest) thatreflected differences in lichen abundance and snow accumulation while reducingmisclassification errors. Resource selection functions were estimated using logisticregression where GPS and Argos satellite telemetry data existed for caribou in theGreater Gros Morne Ecosystem and Middle Ridge regions of Newfoundland and theC?te-Nord region of Quebec. In all regions, telemetry-monitored caribou selected nonforested areas, where lichen abundance was high and snow accumulation was low, more than expected by chance. The similarities in selection of non-forested areas acrossregions despite variation in landscape composition indicates that there are congruenciesboth in the factors influencing winter habitat selection and in the relative value of landcover types on a given landscape. These findings support the argument that resourceselection functions with parameters based on broadly defined land cover types areapplicable among different regions of caribou occurrence and are therefore a valuabletool for understanding patterns of space use in caribou throughout the boreal forest.