Population characteristics of Akodon montensis (Sigmodontinae) in response to habitat degradation and food availability.

Abstract

Small mammal populations can be affected by habitat degradation, causing changes in their abundance, density and movement. Akodon montensis, a persistent host for Orthohantavirus, is a common rodent species in primary and secondary forest habitats and is considered a generalist species. This paper analyzes how habitat degradation and resource availability affect the population characteristics of the species. Six plots were classified into three levels of degradation, with sampling conducted in June and November 2015. After the June sampling, three plots were selected for the increase of food resources for three months, to assess how this factor affects the population. Abundance was estimated with the capture-mark-recapture method and density was estimated by dividing abundance by the effective sampling area. Home range was calculated using the Minimum Convex Polygon method, and the Maximum Distance Traveled as the longest average movement between two sampling stations where an individual was encountered. More degraded habitats supported lower average density and abundance of A. montensis compared to less degraded habitats. Increasing food availability led to increases in abundance in the more degraded habitats and decreases in the least degraded. Changes in home range were most evident, decreasing in the least degraded plots after the increase in resources. The sex ratio did not differ from equity in any plot, nor with respect to any of the factors studied. Population characteristics of the species are determined by several factors, including habitat quality and food distribution and abundance. If changes occur in these factors (either artificially or naturally) then movement, abundance and population density are affected in response to such changes. Although some results were not statistically significant, an apparent interaction was observed between habitat quality and resource availability, thereby influencing the abundance and density of A. montensis.