Effects of weather variability on population dynamics of white-footed mice (Peromyscus leucopus) and eastern chipmunks (Tamias striatus)

Abstract

Research on the potential causes of population fluctuations in small mammals generally has focused more on biotic than abiotic factors. In this study, we asked whether the rate of population change of 2 widespread small rodents in deciduous forests of North America are associated with a set of weather events expected to affect the rodents either directly or indirectly. We analyzed a long-term (1995–2016) livetrapping data set from 6 field plots in southeastern New York, estimated rates of population change for white-footed mice and eastern chipmunks, and asked whether these rates are associated with any of a set of 5 weather variables selected a priori. Rates of population change of white-footed mice (Peromyscus leucopus), but not of chipmunks (Tamias striatus), were significantly lower during hurricane than non-hurricane years and in summers with drought than in non-drought summers. Reduced population growth of white-footed mice occurred during the same or subsequent season but we detected no longer-term effects. Neither species was affected by autumn precipitation, summer heat waves, or winter cold. Hurricane- and drought-induced changes in abundance of white-footed mice could affect their short-term interactions with prey (e.g., gypsy moth pupae, tree seeds, and songbird eggs) and parasites (e.g., ticks and zoonotic pathogens).