Density dependence in within-habitat spatial distribution: contrasting patterns for a rodent and a marsupial in southeastern Brazil

We investigated the relationship between population densities of two species of small mammals and the degree of aggregation in their spatial distributions within a habitat at the Restinga de Barra de Maric , in Rio de Janeiro State. The distribution of the redent Akodon cursor was more clumped at low than at high densities. On the other hand, the aggregation of the marsupial Philander opossum was independent of its abundance. Population density must be included as a variable in quantitative analyses of habitat preferences of those species which, like A. cursor but not P. opossum, show different degrees of habitat selectivity at different population densities.