Short-tailed opossums live mainly on the ground, being less well adapted for climbing than other opossums (5) (7). Thought to be most active at dusk and dawn (1) (4), the shrewish short-tailed opossum feeds mainly on insects, although it will also take some fruits and small vertebrates (8). Like other opossums, it is likely to be a solitary animal (5).
Although little information is available on the breeding behaviour of this species (6), it is likely that, as in other Monodelphis species, breeding occurs throughout the year (7). As is typical in marsupials, the young are born early and poorly developed, with most development taking place after birth, during a prolonged lactation period (5). Unlike many marsupials, the female shrewish short-tailed opossum does not possess a pouch to protect the young as they develop (2) (5) (6). Instead, the young cling to the mother’s mammae (nipples), and later on may ride on her back and flanks (7). Interestingly, the female shrewish short-tailed opossum has the largest number of mammae of any mammal (up to 27). This, together with the extreme sexual dimorphism and the high number of immature individuals that have been collected, suggests that the species is semelparous, meaning it breeds only once, producing a single, large litter of offspring, and then dies, possibly all within its first year of life (3).