influence du climat et de la prédation sur l'utilisation de l'habitat et la ...

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4.1. A bstract
Because the climate is changing, there are now additional incentives to understand the
strategies that organisms use to cope with thennal heterogeneity. The thermal environment
experi enced by an animal is determined by conditions of air temperature, wind, and radi ation,
and habitat can also medi ate the thermal environment. We mapped microclimates by
estimating energy expenditure in mi crohabitats available to North American porcupines
(Erethizon dorsatum) in the cold Canadi an winter. We th en examined acti vity patterns and
microhabitat use of free-Iiving individuals to determine whether porcupines responded
behaviourally to thennal constraints. The lower critical temperature (Tic) of winter
acclimati zed porcupines in southern Québec lies around -2°C and individuals are exposed,
du ring winter, to operative temperatures (Tc) th at are weil below Tic' According to our
thennal map, porcupines reduced metabolic rate by about 25% when moving from a tree to
their den in cold conditions (Tc