Influences of weather and moonlight on activity patterns of small mammals:a biogeographical perspective

We analyzed 15 years of trapping data on prairie voles (Microtus ochrogaste r) and cotton rats (Sigmodon hispidus) to elucidate behavioural responses t o weather by season and time of day. Use of such a long-term data set is ra re and ameliorates many of the problems with short-term data sets typically used for such analysis. The trapping was conducted in the east-central par t of Kansas (U.S.A.), near the southern edge of the distribution of prairie voles and the northern edge of the distribution of cotton rats. These dist ributions provide the framework for differing hypotheses as to responsivene ss of individuals of the two species to weather phenomena as indicated by t he probability of capture. Probability of capture was statistically signifi cantly affected by weather, most frequently by precipitation and temperatur e. Effects varied with season and between species, and were generally consi stent with hypotheses based on the northern (boreal and temperate) history of prairie voles and southern (subtropical and temperate) history of cotton rats and with predation-avoidance hypotheses. Variation in the probabiliti es of capture of cotton rats was more associated with weather, especially i n the colder seasons, than was variation in the probabilities of capture of prairie voles. In summer, capture rates of prairie voles were more suscept ible to weather than were those of cotton rats.