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

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juvenile was moving to escape from us. Juveniles usually didn't move when approached but
we removed al! observations of disturbed or moving juveniles from analyses (n = 8
observations). Our telemetry effort was concentrated in the daytime (90% of locations were
obtained between 9 am and 5 pm). We paid special attention to distribute sampling along the
diurnal cycle evenly across individuals.
Study design
Each time we located an animal, we characterized the habitat where the animal was
hiding and at a paired random location. For both the animal and the random location, we
made one set of measures at the microhabitat scale (within 1 m of the animal or random
location) and one at the local scale (within 15 m of the animal or random location). We first
detennined whether selection for coyer occurred at one or both scales to verify our prediction
1. Because the number of observations was low for some animaIs (mean ± SE: 21 ± 4
observations, range: 2- 47, Table 5.3), we could not determine habitat selection for each
individual. Rather, we determined habitat selection for the population, taking into account the
pseudo-replication in our analyses (following Fortin et al. 2005, see statistical analyses). To
verify our prediction 2, we tested whether the use of coyer depended on meteorological
conditions using data for the population and again taking pseudo-replication into account (see
statistical analyses). Finally, we used mean coyer used by individual juveniles (at both
scales), sex, body mass on 10 June, mean daily movements, and mean distance to the mother
as covariates in survival analyses in order to verify our prediction 3 and test for the effects of
sex, body mass, mobility, and distance to the mother on survival time. Below we detail how
we implemented this study design.
Habitat selection
When we located a juvenile, we first noted whether it was in a den (usually rock dens),
on the ground, or in a tree (at least 30 cm above ground). ]f the juvenile was in a tree, we
recorded the species of the tree and measured its circumference at breast height. Then, we
visually estimated «5%, 5-25%, 25-50%, 50-75%, >75%) the protective coyer (vegetation or
rock, Mysterud & Ostbye 1999) present within 1 m of the porcupine. Finally, we measured
air temperature and wind speed at the animal location using a handheld thermometerwindmeter
(TF A 42.6000.06, TF A Dostmann Ltd Co., Germany). At the local scale (15 m-
radius), we visually estimated «5%, 5-25%, 25-50%, 50-75%, >75%) tree, shrub (any