Behaviuoral changes associated with the population cycle of Antechinus stuartii (Marsupialia)

Abstract

The behaviour of field populations of A. stuartii was monitored in relation to their demography by diad testing. Marked and unmarked pairs were tested in a field observation cage. Two measures of activity and the frequency of 10 behaviour categories were recorded for each test. Stepwise multiple regression analysis showed the sex of the animal and time of year to be the best predictors of aggression parameters. The frequencies of behaviour categories suggest that males and females behave quite differently. Males show a trend of increasing aggressiveness over the annual cycle whereas females do not. Repeated laboratory testing of males in 'mating condition' exacerbates aggression as their weight and general appearance deteriorate. It is suggested that the externally synchronized life cycle programs the aggression increase, and this causes physical deterioration, rather than the reverse.