Habitat requirements of weasels Mustela nivalis constrain their impact on prey populations in complex ecosystems of the temperate zone

Abstract

Differences in habitat use by prey and predator may lead to a shift of occupied niches and affect dynamics of their populations. The weasel Mustela nivalis specializes in hunting rodents, therefore habitat preferences of this predator may have important consequences for the population dynamics of its prey. We investigated habitat selection by weasels in the Białowieza Forest in different seasons at the landscape and local scales, and evaluated possible consequences for the population dynamics of their prey. At the landscape scale, weasels preferred open habitats (both dry and wet) and avoided forest. In open areas they selected habitats with higher prey abundance, except during the low-density phase of the vole cycle, when the distribution of these predators was more uniform. Also in winter, the distribution of weasels at the landscape scale was proportional to available resources. In summer, within open dry and wet habitats, weasels preferred areas characterised by dense vegetation, but avoided poor plant cover. In winter, weasels used wet open areas proportionally to availability of habitats when hunting, but in contrast to summer, they rested only in habitats characterized by a lower water level, which offered better thermal conditions. At the local scale, the abundance of voles was a less important factor affecting the distribution of these predators. Although we were not able to provide direct evidence for the existence of refuges for voles, our results show that they may be located within habitat patches, where availability of dense plant cover and physiological constraints limit the activity of weasels. Our results indicate that in complex ecosystems of the temperate zone, characterized by a mosaic pattern of vegetation types and habitat specific dynamics of rodents, impact of weasels on prey populations might be limited.

Testing mechanistic explanations for mammalian predator responses to habitat edges

“…Nevertheless, habitat quality for predators also includes other (complementary) sources than food. Carnivore species with small and slim bodies such as small mustelids have special thermoregulation requirements which significantly alter their habitat choice (Jędrzejewski and Jędrzejewska 1993;Jędrzejewska and Jędrzejewski 1998;Zub et al 2008Zub et al , 2009). In addition, these species are subjected to predation by larger predators (Crooks and Soulé 1999;Korpimäki and Norrdahl 1989;St-Pierre et al 2006).…”

“…This situation is generally predicted in the following cases: (3) resources may be concentrated specifically in an edge structure; or (4) alternatively, if a core habitat contains complementary resources (qualitatively different), predators will profit from the exploitation of the habitat edge due to the spatial proximity of both types of resources ). These complementary resources may include, for example, foraging opportunities in one habitat vs. effective dispersal (i.e., the travel line hypothesis Bider 1968) or vegetation cover for special thermoregulation requirements (e.g., Jędrzejewska and Jędrzejewski 1998;Zub et al 2008Zub et al , 2009 in the second habitat. Finally, (5) predator specialists typical for one habitat may mix with predators typical for the second habitat.…”

The energy cost of voluntary running in weasels,Mustela nivalis

“…Previous work on this weasel population has included measurements of activity patterns (Jedrzejewski et al, 1995;Jedrzejewski et al, 2000), resting energy metabolism (Szafrañska et al, 2007), habitat use (Jedrzejewski and Jedrzejewski, 1998;Zub et al, 2008) and field metabolic rates (Zub et al, 2009), and we followed the handling procedures detailed in those studies. In brief, captured weasels were transported to our laboratory at the Mammal Research Institute in the town of Białowieza, housed in cages that included a shelter with bedding, and provided with water ad libitum and one to two laboratory mice per day (depending on weasel body mass).…”

“…In that context, a potentially important factor is the high hunting efficiency of weasels in the Białowieza area: weasels in this area are often able to capture prey sufficient for their daily energy requirements in 1 to 2h of active hunting (Zub et al, 2011). Field studies show that weasels preferentially use areas with high prey abundance, which increases their hunting efficiency and allows activity time to be minimized (Zub et al, 2008).…”

Experimental evidence that livestock grazing intensity affects cyclic vole population regulation processes

“…Indirect effects of grazing on landscape structure and connectivity might influence macro-parasite prevalence and transmission (Brownstein et al 2005;Halos et al 2010), so that grazing intensity and vole parasitism might be linked. Grazing impact on landscape structure and connectivity might also have influenced predator foraging opportunities, e.g., by increasing avian predation or decreasing risk-averse mustelid foraging behaviour (Zub et al 2008), conceivably leading to a net reduction in delayed density dependence (Bjørnstad et al 1995;Hanski et al 2001). Predation would be expected to have synchronised cycles of adjacent prey populations, as shown in microcosm experiments (Vasseur and Fox 2009) and field experiments involving small mammals (Korpimäki and Krebs 1996;Ims and Andreassen 2000).…”