ECOLOGICAL STRATEGIES OF THE DESERT MOUSE OPOSSUM, THYLAMYS PALLIDIOR, IN THE MONTE DESERT, ARGENTINA

ALBANESE, MARIA SOLEDAD; DACAR, MARÍA ANA; OJEDA, RICARDO A

Mendoza, Argentina

Congreso; Xth International Mammalogical Congress; 2009

International Federation of Mammalogists

ECOLOGICAL STRATEGIES OF THE DESERT MOUSE OPOSSUM, THYLAMYS PALLIDIOR, IN THE MONTE DESERT, ARGENTINA M. Soledad Albanese*, M. Ana Dacar, and Ricardo A. Ojeda Grupo de Investigaciones de la Biodiversidad, IADIZA, CONICET, CCT. CC 507, 5500 Mendoza, Argentina; salbanese@mendoza-conicet.gov.ar The desert mouse opossum is a small marsupial inhabiting the aridlands of South America with the largest distribution in the genus. Knowledge about its ecology is scarce being this the first ecological study of a marsupial in the Monte. The objective of our research was to characterize three aspects of its ecology (population structure, habitat use and diet) in a seasonal and heterogeneous environment. During 2005-2007 we sampled four seasons and three habitat types (Prosopis woodland, Larrea shrubland and sand dunes) in the MaB Ñacuñan Reserve, Mendoza. In each habitat we set up 6 grids (36 Sherman ground traps+10 tree traps) the first year and 4 grids the second year. Individuals were measured, marked and released at the capture site. Habitat use was analyzed at three spatial scales (habitat, grid, and patch). We captured 118 mouse-opossums (capture effort: 27600 trap-nights). Our results showed that abundance and reproduction were strongly seasonal and influence by rainfall. We also found evidence of possible semelparity. Habitat utilization varied seasonally; during wet season mouse opossum used the habitat indistinctly, whereas during dry season selected areas with low complexity and high grass cover. This utilization pattern was better explained by the spatial scale of grid (1 ha). The diet is composed by arthropods (71.5%), and unlike Australian desert small marsupials, T.pallidior feeds also on leaves (22.44%), fruits (3.13%) and seeds (2.3%) showing a generalist feeding strategy. This composition does not vary between seasons, sex or age classes. Except for its diet, this species showed strong seasonality in many aspects of its natural history. These strategies, coupled with physiological adaptations, allow the desert mouse opossum to cope with rigorous conditions that characterize the Monte desert. (Supported by PICT-AGENCIA 11768-25778-PIP CONICET-5944).