Environmental variables and reproductive activity in small rodents of pampean agroecosystems

Under the hypothesis that the reproductive activity of a rodent species is influenced by conditions of the environment and by coexistent rodents, we assessed the relationship between environmental variables and reproductive activity of rodents at two spatial scales, field borders and trap sites, during the breeding period (spring, summer and autumn seasons) in pampean agroecosystems of Argentina. We distinguished between active and inactive sites, based on female reproductive condition. We conducted several statistical analyses to compare between active/inactive borders and trap sites for vegetation-rodent and rodent-rodent associations. The environmental variables useful for distinguishing active sites from inactive ones were different for each rodent species. Whereas vegetation cover, at the two habitat scales analyzed, seemed to be important for Akodon azarae, the crop types adjacent to borders seemed to be significant for Calomys musculinus to differentiate active/inactive sites. In the case of Calomys venustus, we could not identify one variable that reflected differences between border types. These associations would be related to the use that each rodent species makes of border and cropfield habitats, together with the resources they need at each moment of the breeding period.