关键词: 数量统计, 食物资源, 橙腹田鼠, 草原田鼠, 附加食物

Abstract: We studied responses of populations of Microtus ochrogaster and M. pennsylvanicus in east-central Illinois,USA to supplemental food in intermediate (bluegrass)and low (tallgrass prairie) food habitats. Whereas amplitudes of fluctuation of M . ochrogaster were higher in supplementally fed than in control sites in intermediate food habitat,mean population densities and patterns of fluctuation did not differ between the two sites in either habitat. Mean population densities of M. pennsylvanicus were higher in supplementally fed than in control sites only in low food tallgrass habitat. Supplemental food did not positively influence survival or maturation rates of M. ochrogaster in either habitat;the proportion of eproductively active adult females and adult male body mass were higher only in supplementally fed sites in intermediate food habitat. Supplemental food did not influence any variable of M. pennsylvanicus in bluegrass,nor survival in tallgrass,whereas maturation rates were shortened and proportion reproductively active females,immigration,and male body mass were greater in supplementally fed low food habitat. We conclude that food resources play only a minor role in driving the dynamics of populations of M . ochrogaster and M. pennsylvanicus.

Key words: Demography, Food resources, Microtus ochrogaster, Microtus pennsylvanicus, Supplemental feeding