Ecological coexistence of low-density populations of Apodemus sylvaticus and A. flavicollis (Mammalia: Rodentia)

The population size (estimated by POPAN method) and potential interspecific competition and spatial distribution in relation to vegetation features were studied in two sympatric and syntopic rodent species, Apodemus sylvaticus and Apodemus flavicollis. The study was performed by capture-mark-recapture study within a trap grid, at two adjacent forest sites in Mediterranean central Italy. We found that the population sizes of the two rodent species were comparatively lower than those recorded in conspecifics from other central Italian areas, and that the potential for interspecific competition was low at both sites, as revealed by the lack of negative correlations between the relative abundances of the two species after Monte Carlo analyses. The number of captures of both rodent species was not correlated to either the number of trees in each grid cell or the sum of tree diameters. The general implications of the obtained results are discussed.