Can predation cause the 10-year hare cycle?

We relate causes of mortality of snowshoe hares to density of hares over an 8-year period that included a peak in numbers. We then use simulation modeling to examine whether these density-dependent relationships could produce changes in hare density similar to those observed in our study are in Yukon, Canada.Predation during winter was the largest source of mortality for snowshoe hares at Kluane, Yukon during 1978-84. There was a one-year lag in the response of winter predation mortality rate to hare density. There was a two-year lag in the response of winter mortality not caused by predators to hare density.A simple simulation model with density-dependent predation produced 8-11 year cycles only within a narrow range of parameters that are inconsistent with data from the Kluane region. However, a simulation model that predicted winter mortality rates using a delayed density-dependent numerical response and a Type II functional response by predators, produced 8-11 year cycles within the range of parameter values measured in our study. Yet another simulation model that predicted both summer and winter mortality rates using a delayed density-dependent numerical response and a Type II functional response by predators, did not produce 8-11 year cycles within the range of parameter values measured in our study. Lack of data on juvenile mortality may be one reason for this result.