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Peers, Michael; Majchrzak, Yasmine; Menzies, Allyson; Studd, Emily; Bastille-Rousseau, Guillaume; Boonstra, Rudy; Humphries, Murray; Jung, Thomas; Kenney, Alice; Krebs, Charles; Murray, Dennis; Boutin, Stan 2021-06-16 <p style="text-indent:36.0pt;">Canada lynx (<i>Lynx canadensis</i>) and snowshoe hares (<i>Lepus americanus</i>) form a keystone predator-prey cycle that has large impacts on the North-American boreal forest vertebrate community. Snowshoe hares and lynx are both well-suited for snowy winters, but climate change associated shifts in snow conditions could lower hare survival and alter cyclic dynamics. Using detailed monitoring of snowshoe hare cause-specific mortality, behaviour, and prevailing weather, we demonstrate that hare mortality risk is strongly influenced by variation in snow conditions. Although predation risk from lynx was largely unaffected by snow conditions, coyote (<i>Canis latrans</i>) predation increased in shallow snow. Maximum snow depth in our study area has decreased 33% over the last two decades and predictions based on prolonged shallow snow indicate future hare survival could resemble that seen during population declines. Our results indicate that climate change could disrupt cyclic dynamics in the boreal forest.</p>
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Dryad
Peers, Michael; Konkolics, Sean; Lamb, Clayton; Majchrzak, Yasmine; Menzies, Allyson; Studd, Emily; Boonstra, Rudy; Kenney, Alice; Krebs, Charles; Martinig, April Robin; McCulloch, Baily; Silva, Joseph; Garland, Laura; Boutin, Stan 2020-10-09 <p>1. Scavenging by vertebrates can have important impacts on food web stability and persistence, and can alter the distribution of nutrients throughout the landscape. However, scavenging communities have been understudied in most regions around the globe, and we lack understanding of the biotic drivers of vertebrate scavenging dynamics.</p> <p>2. In this paper, we examined how changes in prey density and carrion biomass caused by population cycles of a primary prey species, the snowshoe hare (<i>Lepus americanus</i>), influence scavenging communities in the northern boreal forest. We further examined the impact of habitat and temperature on scavenging dynamics.</p> <p>3. We monitored the persistence time, time until first scavenger, and number of species scavenging experimentally-placed hare carcasses over four consecutive years in the southwestern Yukon. We simultaneously monitored hare density and carrion biomass to examine their influence relative to temperature, habitat, and seasonal effects. For the primary scavengers, we developed species-specific scavenging models to determine variation on the effects of these factors across species, and determine which species may be driving temporal patterns in the entire community.</p> <p>4. We found that the efficiency of the scavenging community was affected by hare density, with carcass persistence decreasing when snowshoe hare densities declined, mainly due to increased scavenging rates by Canada lynx (<i>Lynx canadensis</i>). However, prey density did not influence the number of species scavenging a given carcass, suggesting prey abundance affects carrion recycling but not necessarily the number of connections in the food web. In addition, scavenging rates increased in warmer temperatures, and there were strong seasonal effects on the richness of the vertebrate scavenging community.</p> <p>5. Our results demonstrate that vertebrate scavenging communities are sensitive to changes in species’ demography and environmental change, and that future assessments of food web dynamics should consider links established through scavenging.</p>

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