Sex differences in aggressive behavior in a marsupial,the gray short-tailed opossum (Monodelphis domestica)

In male and female gray short-tailed opossums (Monodelphis domestica), same-sex interactions were characterized by high levels of threat behavior (open-mouth postures and screeching vocalizations). Actual fighting behavior (biting, locking, and tumbling) was seen almost exclusively in male-male interactions. In male-female interactions, females showed high levels of threat behavior and males showed little aggressive behavior of any kind. Clicking vocalizations, submissive behavior in marsupials, were displayed almost exclusively by males. These findings are discussed with respect to the uses of auditory and olfactory communication in marsupials.