Abstract
Cyclic population fluctuations are common in boreal and Arctic species but the causes of these cycles are still debated today. Among these species, lemmings are Arctic rodents that live and reproduce under the snow and whose large cyclical population fluctuations in the high Arctic impact the whole tundra food web. We explore, using lemming population data and snow modeling, whether the hardness of the basal layer of the snowpack, determined by rain-on-snow events (ROS) and wind storms in autumn, can affect brown lemming population dynamics in the Canadian high Arctic. Using a 7-year dataset collected on Bylot Island, Nunavut, Canada over the period 2003–2014, we demonstrate that liquid water input to snow is strongly inversely related with winter population growth (R2 ≥ 0.62) and to a lesser extent to lemming summer densities and winter nest densities (R2 = 0.29–0.39). ROS in autumn can therefore influence the amplitude of brown lemming population fluctuations. Increase in ROS events with climate warming should strongly impact the populations of lemmings and consequently those of the many predators that depend upon them. Snow conditions may be a key factor influencing the cyclic dynamics of Arctic animal populations.
Highlights
Large amplitude cyclic population fluctuations have been documented in several vertebrate species for a long time (Elton 1924; Krebs 2013) and are especially prevalent in boreal and Arctic species (Stenseth 1999; Krebs 2011)
Model runs revealed that all contributions to SWi in autumn were from rain-on-snow events (ROS) events
Our results generally support our hypothesis that the hardness of the basal snow layer, as predicted by the amount of liquid water brought by ROS events in the autumn, negatively affects brown lemming demographic parameters
Summary
Large amplitude cyclic population fluctuations have been documented in several vertebrate species for a long time (Elton 1924; Krebs 2013) and are especially prevalent in boreal and Arctic species (Stenseth 1999; Krebs 2011). Small mammals of the Arctic tundra such as lemmings and voles provide food for a whole suite of avian and mammalian predators such as snowy owls (Bubo scandiacus), ermines (Mustela erminea), long-tailed jaegers (Stercorarius longicaudus), rough-legged hawks (Buteo lagopus), and Arctic foxes (Vulpes lagopus) (Gauthier et al 2013). They constitute a central link in the terrestrial food web (Gilg et al 2003; Krebs 2011). Snow conditions may play a role in the cyclic dynamics of small mammals because they live, feed, and can reproduce under the snow for most of the year (Ims et al 2008; Fauteux et al 2015; Berteaux et al 2017)
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