What has stopped the cycles of sub-Arctic animal populations? Predators or food?

Abstract

The populations of many species of sub-Arctic animals have recently ceased to fluctuate cyclically. The ultimate cause of this would seem to be changes in the weather, and the proximate cause has been credited to less winter snow allowing predators better access to their prey, thus enabling them to prevent surges in the prey's abundance. But there is evidence that this is not so; that, rather, the numbers of predators are limited by the abundance of their prey. Furthermore, there is alternative evidence that suggests that changes in the cyclical availability of food, brought about by changing weather conditions, may be dampening fluctuations in the abundance of these populations. On the wider ecological front, the evidence presented here further supports the commonality of how a shortage of food of a quality that can support breeding, not the action of predators, generally limits the abundance of populations of both prey and predator. © 2011 Gesellschaft für Ökologie.