Behaviors of captive short-tailed opossums, Monodelphis dimidiata (Wagner,1847) (Didelphimorphia, Didelphidae).

We studied captive behavior of Monodelphis dimidiata, a small, grassland-in habiting opossum occurring in Argentina, Uruguay, and southern Brazil. Alth ough primarily terrestrial, it can also climb, but is a poor jumper. Groomi ng behaviors are similar to those of other opossums. Food detection seems t o be primarily by olfaction, with vision and audition being used only suppl ementarily. M. dimidiata exhibits a suite of specialized predatory behaviou ral patterns for dealing with various prey, such as dehairing hairy caterpi llars, crunching the head of arthropods, and killing mice by means of a nec k bite. As do other opossums, M. dimidiata carries nesting material with it s tail. M. dimidiata has a similar vocal repertoire to those of other membe rs of the family, including clicking sounds, screeches and growls. Compared with other opossums, M. dimidiata seems to be quite tolerant of conspecifi cs, except in interactions involving adult males. The intolerance between a dult males and the extreme sexual dimorphism observed in the species may be related to the particular life history shown by M. dimidiata : a semelparo us annual pattern.