Where to spend the winter? The role of intraspecific competition and climate in determining the selection of wintering areas by migratory caribou

Depicted as predictable movements, migrations can, however, show important interannual variations, making the conservation of migratory species particularly challenging. Plasticity in migratory behaviour allows individuals to adjust their migratory tactics to maximize their fitness. Destination of migration, and therefore migration patterns, may vary according to climatic and environmental conditions encountered during migration or at the arrival site but also according to competition. In Northern-Québec and Labrador, Canada, fall migration patterns of caribou from the Rivière-George (RGH) and the Rivière-aux-Feuilles (RFH) herds have varied greatly during the last decades. Meanwhile, both herds have shown large fluctuations in abundance. We assessed the influence of environmental factors and changes in population size on wintering area selection. Based on 649 fall migrations of 284 females equipped with ARGOS collars, we used a machine-learning algorithm, the random forests, to assess ...