Density Cycles in an Island Population of Deer Mice, Peromyscus maniculatus

Abstract

We report on eight years of data for a population of deer mice on Santa Barbara Island, California which reaches exceptionally high densities and fluctuates markedly in an apparent three- to four-year cycle. The cyclic increase follows winters with high rainfall, and the decline may be similarly associated with low rainfall winters. The peak and early decline is marked by nearly complete cessation of breeding, along with heavy predation by barn owls (Tyto alba), whose numbers track those of the deer mice