Microhabitat use and density of sigmodontine rodents in Spartina densiflora freschwater marshes, Argentina

BONAVENTURA, S. M.; VERONICA ANDREA PANCOTTO; MADANES, N.; VICARI, R.

MAMMALIA

WALTER DE GRUYTER & CO

Año: 2003 vol. 67 p. 367 - 377

0025-1461

We analyzed the influence of habitat heterogeneity and population density on the microhabitat use of four sigmodontine rodents: Akodon azarae, Oligoryzomys flavescens, Scapteromys tumidus and Oxymycterus rufus. Rodents were livetrapped over a period of 2 years in 9,600 m2 rectangular grid (24 trap stations). In the first year, abundance, residence and reproduction of rodents were associated with elevated flood-protected microhabitats, both with high plant cover (A. azarae, O. flavescens and S. tumidus) and intermediate plant cover (O. rufus). Morphological swimming adaptations may account the abundance and large number of resident and reproductive individuals of S. tumidus in flooded microhabitats with low plant cover. During the second year, no differences in microhabitat use were found among rodent species. We suggest that the observed interannual changes in rodent microhabitat use are a consequence of increased intra- and interspecific interactions  associated with the increased abundance of A. azarae and O. flavescens during the second year. Variations in microhabitat use are not independent of weather conditions. Thus, the increased abundances of A. azarae and O. flavescens were associated with the warm autumn-winter and the rainy spring-summer periods of the second year. The decreased abundance of S. tumidus may have resulted from the dry spring-summer period of the first year.