Predation and Animal Populations : Lessons from Lemmings and Geese

Résumé

Deborah Wilson, recipient of the Lorraine Allison Scholarship for 1997, has designed her doctoral research to answer the following two questions about lemming and goose population dynamics. First, do predators cause the lemming decline? And second, how does the lemming cycle affect predation on goose nest? To this end she experimentally protected an 11-hectare patch of tundra from predators, with a fence to deter large predatory mammals and monofilament fishing line overhead to deter predatory birds. The results of this experiment are reported along with the results of the second part of her study which emphasizes that a decline in abundance of one type of prey may have unexpected deleterious effects not only on its predators but also on other prey species. "These observations may be relevant when outbreaks of disease kill prey animals, or when wildlife managers attempt to remove introduced pest species. To be able to make predictions about the population dynamics of alternative prey, it is necessary to take into account spatial patterns, delayed effects, the foraging behaviour of predators, and interactions among different species of predators."