Response of an arctic predator guild to collapsing lemming cycles

Abstract

Alpine and arctic lemming populations appear to be highly sensitive to climate change, and when faced with warmer and shorter winters, their well-known high-amplitude population cycles may collapse. Being keystone species in tundra ecosystems, changed lemming dynamics may convey significant knock-on effects on trophically linked species. Here, we analyse long-term , community-wide monitoring data from two sites in high-arctic Greenland and document how a collapse in collared lemming cyclicity affects the population dynamics of the predator guild. Dramatic changes were observed in two highly specialized lemming predators: snowy owl and stoat. Following the lemming cycle collapse, snowy owl fledgling production declined by 98 per cent, and there was indication of a severe population decline of stoats at one site. The less specialized long-tailed skua and the generalist arctic fox were more loosely coupled to the lemming dynamics. Still, the lemming collapse had noticeable effects on their reproductive performance. Predator responses differed somewhat between sites in all species and could arise from sitespecific differences in lemming dynamics, intra-guild interactions or subsidies from other resources. Nevertheless, population extinctions and community restructuring of this arctic endemic predator guild are likely if the lemming dynamics are maintained at the current non-cyclic, low-density state.

Climate Events Synchronize the Dynamics of a Resident Vertebrate Community in the High Arctic

“…Warmer and rainier winters may already have contributed to dampened fluctuations in many rodent populations (16,18) and the decline in many caribou and reindeer populations in the northern hemisphere (31). Such changes are, in turn, expected to influence other ecosystem components (17,32), as shown here. The present study therefore represents a bellwether of how future changes in climate and extreme events during winter may contribute to shape ecosystem functioning and stability in the terrestrial Arctic.…”

Serial population extinctions in a small mammal indicate Late Pleistocene ecosystem instability

“…We further suggest that the observed pattern of extirpation and recolonization is not unique to the collared lemming (27) and is likely characteristic of other small mammal species during this period. However, as one of the keystone prey species in the Arctic ecosystem (28), the localized absences of collared lemming reported here would have had significant bottom-up impacts on the glacial steppe-tundra predator community.…”

Effects of changing permafrost and snow conditions on tundra wildlife: critical places and times

“…Indeed, persistent low populations of small mammals, such as those reported in eastern Greenland for the past 15 years, can have a considerable impact on the numerous predators that depend upon lemmings for their survival (Schmidt et al 2012). On Svalbard, the impact of rain-on-snow events on herbivores had a cascading positive impact on the Arctic fox, the only resident predator in this simple food web, due to increased carrion resulting from reindeer mortality (Hansen et al 2013).…”