Which population density affects home ranges ofco-occurring rodents?

Animal space use patterns can be affected by the intra- and interspecific density of individuals competing for resources,with home ranges generally decreasing with increasing population density. By applying spatially explicit capture-recapturemodels implemented in the R package secr, we study whether home ranges of co-occurring yellow-necked mice, Apodemusflavicollis, and bank voles, Myodes glareolus, are related to population density of (a) conspecifics (intraspecific density), (b)the other sympatric species, A. flavicollis or M. glareolus (interspecific density), or (c) total rodent density (A. flavicollis plusM. glareolus). Home ranges of both species were negatively related to intraspecific population density, and were not related tointerspecific density or total rodent density. Given that rodents tend to reduce home ranges if resources are abundant, this patternmay merely result from the higher abundance of resources generally associated with high density populations, if the two specieswere responding to different subsets of resources. However, intraspecific density could directly reduce home ranges, becauseconspecifics are more likely to interfere with each other due to the overlapping of space use patterns. Therefore, results suggestcomplementary space or resource use patterns between species, with consequent weak competition and niche differentiation.Across several years and population densities, home ranges of the two co-occurring rodents thus appear to be affected byconspecifics only, suggesting that the two species may coexist in the study area owing to limited space or resource use overlap.© 2018 Gesellschaft f¨ur¨Okologie. Published by Elsevier GmbH. All rights reserved.