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

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Operative temperature (OC)
Figure 4.4 : Estimated time spent feed ing (mean ± SE) in a day for male (white bars) and
female (dark bars) NOlih American porcupines, Parc National du Bic, Québec, January to
Apri l, 2004-2005. Time spent feeding was estimated for each individual and class of
operative temperature (Tc) and then averaged for males and females for each c\ass of Tc.
4.5. Discussion
Estimated energy expenditure differed across microhabitats for a given Tc and the
re lationship between energy expenditure and microhabitat varied with Tc. ln other words,
ranking of microhabitats from microhabitat offering the best, to microhabitat offering the
worst thermal environment was not the same at co Id and warm Tc. Dens offered the best
protection against cold temperatures. Porcupines altered their patterns of den use and
foraging behaviour according to Te. When Tc decreased, they reduced the time spent outside
of the den, increased the number of activity bouts per day, reduced the duration of activity
bouts, became more diurnal, and increased feeding intensity. Activity patterns also varied
with snow conditions. Olltside of the den, porcupines did not modify their microhabitat lise
according to Te. Rather, they llsed microhabitats according to their activities: they exploited
open microhabitats and top of trees for feeding and covered microhabitats and bottom of trees
for resting. Porcupines also showed sex differences in their patterns of habitat use.