鼠类种群动态:食物资源影响力的实验评估

本研究在美国伊利诺斯州中东部测定了中等食物质量(莓系属的牧草)和低食物质量(高杆草牧场)栖息地内橙腹田鼠(Microtusochrogaster)和草原田鼠(M.pennsylvanicus)种群对附加食物的响应。在中等食物质量栖息地内投放附加食物,橙腹田鼠种群的波动幅度高于对照样地,但同类型食物质量栖息地内,种群平均密度和波动模式无显著的差异。仅在低等食物质量的高杆草栖息地内,投放附加食物可导致草原田鼠的种群密度高于对照样地。附加食物不直接影响两种栖息地内橙腹田鼠的成活率或成熟率,在中等食物质量栖息地中投放附加食物,繁殖活跃的成熟雌性个体比例及雄性成体的体重高于对照。附加食物不影响莓系属牧草内草原田鼠,也不能影响该动物在高杆草环境中的存活率。然而,投放附加食物,可缩短低等食物质量栖息地内草原田鼠的成熟期,提高繁殖活跃雌性的比例和迁入个体比例,增加并引起雄性个体体重增加。据此,本研究证明食物资源在橙腹田鼠和草原田鼠种群动态中只起极小的作用。

Dynamics of vole populations: an experimental evaluation of the influence of food resources

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 reproductively 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.