Seasonal variations in microhabitat use and feeding habits of the pampas mouse Akodon azarae in agroecosystems of central Argentina

Abstract

We studied microhabitat use and food habits of the pampas mouse Akodon azarae (Fischer, 1829), in agroecosystems of central Argentina. In summer (breeding season), A. azarae inhabited both cropfields and their weedy borders. Sexually active females were caught at microhabitats with 31% more green cover than inactive ones. The percentage of invertebrates in the stomach contents of females was 104% greater than in males. In winter (non-breeding season), individuals were restricted to the borders, selecting sites with high levels of forbs and green cover. There were no significant differences between the sexes, either in microhabitat use or in food habits. We propose that reproduction of females is influenced by green cover, and that a decrease of this resource may reduce breeding activity of females in the borders after most plants enter senescence. Females would feed on insects as a source of proteins, which are required for reproduction. In winter, when the population is sexually inactive, individuals of both sexes have similar requirements and occupy the most suitable sites available within a low-quality habitat. We conclude that seasonal variations in microhabitat use and food habits of A. azarae are mainly influenced by changes in resource availability and reproductive status of individuals.