| Global warming as a result of increased concentrations of greenhouse gases in the lower atmosphere and decreased ozone levels in the upper atmosphere has been predicted for the coming decades. Changes we may experience as a result of such climatic phenomena as global warming have profound implications for human society and other life on earth. Kansas, as well as the rest of the Great Plains region of the United States may experience some of the more drastic effects associated with global climatic change. I examined two long-term (1975-1993 and 1986-1992) sets of small-mammal population data, and investigated the responses of individuals and populations to weather and to climatic trends.; Cotton rats (Sigmodon hispidus) and prairie voles (Microtus ochrogaster) are sympatric and ecologically similar in eastern Kansas. However, Kansas represents the southern range of prairie voles and the northern range of cotton rats. Thus, the two species may be better adapted to more northerly and more southerly climes, and I expected them to respond differently to the extreme weather conditions of Kansas.; Probabilities of capture of both species varied with weather, in keeping with hypotheses of minimization of physiological stress and predation risk. Populations of both species responded similarly to extreme climatic trends, but were affected to different degrees. As a result, warming climates may extend the reproductive season for cotton rats, and reduce population growth rates of voles in summer, thus altering the small-mammal community composition.; Under extreme drought conditions, cotton rats use shrinkage cracks in the soil as refuges, whereas prairie voles largely ignore them. This behavior may affect species-specific survival rates, and further contribute to the higher relative abundance of cotton rats in the community.; Finally, timing of trapping is not particularly important when assessing probabilities of capture. If researchers wish to avoid extreme weather by varying their trapping schedules slightly, variation in weather will not be much different except as regards temperature, and differences in variation of probabilities of capture between set and flexible protocols will be slight. I also noted that population estimates based on removal trapping may be severely biased due to daily changes in probabilities of capture due to weather. |
