Manuscript - Home range dynamics of sympatric vole populations: influence of food resources, population density, interspecific competition, and mating system

摘要

We studied variation in home range size in fluctuating populations ofMicrotus ochrogaster and M. pennsylvanicus in alfalfa, bluegrass andtallgrass habitats over a 25-year period in east-central Illinois. Thethree habitats differed in food availability and vegetative cover.Home range indices of both species were complexly related to abundanceof food resources. Home ranges of M. ochrogaster were smallest in thehigh food habitat (alfalfa), largest in the low food habitat(tallgrass) and intermediate in medium food habitat (bluegrass). M.pennsylvanicus home ranges were largest in the low food habitat, butdid not differ between the high and intermediate food habitats. M.ochrogaster did not have smaller home ranges in supplementally fedmedium and low food habitats; those of M. pennsylvanicus were smalleronly in the low food habitat. Home ranges of M. ochrogaster werecompressed only at population densities above 100/ha, irrespective offood levels; those of M. pennsylvanicus were smaller at high densitiesonly in medium and low food habitats. Presence of the other speciesdid not influence size of home ranges of either species. Withinhabitatseasonal variation in home range indices indicated aconfounding response to cover (prey risk) and food. Home ranges of allage classes of M. pennsylvanicus were larger than those of M.ochrogaster in all three habitats. There was no obvious relationshipbetween home range sizes of adult males and females in relation to themating system of each species. For both species in all three habitats,home ranges of adult males were larger than those of adult females.