Physiological correlations of population density in the eastern chipmunk (Tamias striatus) and the white-footed mouse (Peromyscus leucopus)

Populations of various densities of eastern, chipmunks (Tamias striatus lysteri (Richardson) and white-footed mice (Peromyscus leucopus noveboracensis (Fischer) were formed by the introduction of wild-trapped animals onto islands of different size on Heney (Little Whitefish) Lake, Quebec.The animals were subsequently recaptured and various indicators of adrenocortical activity, including levels of circulating eosinophils and plasma corticostcroids, were measured. The evidence indicated that activation of the adrenal cortex is directly correlated with population density in T. striatus but not in P. leucopus.The conclusions are discussed in relation to current theories on the regulation of mammalian population including J. J. Christian's hypothetical behavioural–physiological control mechanism.