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

47
Causes of mortality
We assigned a probable cause of mOltality to 46 of the 50 porcupines examined.
Predation (n = 28 [60.9%]) and starvation (n = 13 [28.3%]) were the main causes of
mortality. Tree fal! (n = 3) and road kil! (n = 2) together represented 10.8% of the mortalities.
We detem1ined predator identity for 14 of the 28 predation events observed. Fishers were
responsible for 86% (n = 12) and coyotes for 14% (n = 2) of these predations. The proportion
of mottalities due to predation vs. other causes (starvation, tree fall and road kill combined)
was not constant through time (G = 8.640, df = 3, p = 0.034) and increased from 40% in 2000
and 2002 to 91.7% in 2004 (Fig. 3.3). Causes ofmortality did not differ between age classes
(G = 1.399, df = 3, p = 0.706, Fig. 3.4).
100.0
10 5 19 12
90.0
80.0
~
~ 70.0
1/)
Cl)
:e 60.0
Iii
1::
0 50.0
:::iE
40.0
30.0
20.0
10.0
0.0
2000 2002 2003 2004
Figure 3.3 : Causes of mortality determined for carcasses found during monitoring of a
NOIth American porcupine population in Parc National du Bic, Québec, May 2000-May
2006. Percentage of carcasses dead by starvation, road ki ll, tree fal! and predation are shown
respectively in white, Iight grey, dark grey and black. Sample sizes for each year are
indicated at the top of each bar.