Abstract
AbstractPredator space use influences ecosystem dynamics, and a fundamental goal assumed for a foraging predator is to maximize encounter rate with prey. This can be achieved by disproportionately utilizing areas of high prey density or, where prey are mobile and therefore spatially unpredictable, utilizing patches of their prey's preferred resources. A third, potentially complementary strategy is to increase mobility by using linear features like roads and/or frozen waterways. Here, we used novel population‐level predator utilization distributions (termed “localized density distributions”) in a single‐predator (wolf), two‐prey (moose and caribou) system to evaluate these space‐use hypotheses. The study was conducted in contrasting sections of a large boreal forest area in northern Ontario, Canada, with a spatial gradient of human disturbances and predator and prey densities. Our results indicated that wolves consistently used forest stands preferred by moose, their main prey species in this part of Ontario. Direct use of prey‐rich areas was also significant but restricted to where there was a high local density of moose, whereas use of linear features was pronounced where local moose density was lower. These behaviors suggest that wolf foraging decisions, while consistently influenced by spatially anchored patches of prey forage resources, were also determined by local ecological conditions, specifically prey density. Wolves appeared to utilize prey‐rich areas when regional preferred prey density exceeded a threshold that made this profitable, whereas they disproportionately used linear features that promoted mobility when low prey density made directly tracking prey distribution unprofitable.
Highlights
Predators influence survival, demography, and the spatial distribution of their prey through direct predation and the non-lethal risk of predation (Ripple et al 2014), processes influenced by predator space-use patterns (Kauffman et al 2007, McPhee et al 2012a, Middleton et al 2013)
Deciduous/mixed forest was represented in both top HABITAT models and was strongly positively associated with probability of wolf use (Table 2), suggesting that wolves actively select for this important moose foraging habitat
Disturbed forest, another habitat type preferentially selected by moose, was strongly positively associated at the disturbed site, whereas sparse forest was retained in the top model for the undisturbed site, expressing a weak negative association
Summary
Demography, and the spatial distribution of their prey through direct predation and the non-lethal risk of predation (Ripple et al 2014), processes influenced by predator space-use patterns (Kauffman et al 2007, McPhee et al 2012a, Middleton et al 2013). Mobile prey can be spatially unpredictable, so an alternate strategy is to track areas where prey foraging habitat is abundant (Mitchell and Lima 2002). Termed “leap-frogging” (Sih 2005), the prey habitat hypothesis, predicted by tri-trophic foraging models that allow predators and prey to move and respond to each other’s movements (Iwasa 1982), has rarely been empirically tested (Hammond et al 2007), at large spatial scales (Flaxman and Lou 2009). An enhanced understanding of the processes driving landscape-level predator spatial behavior allows for the advancement of ecological theory (Lima 2002) and is necessary to effectively manage populations increasingly impacted by anthropogenic activities
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