Some seasonal changes in Antechinus flavipes (Marsupialia : Dayuridae)

Abstract

Seasonal changes in some basic bioenergetic functions were investigated in the marsupial mouse A. flavipes by comparing normal males with females and castrated males. The activity and body weight of intact males increased to a peak in late June, at the same time metabolic rate increased. After the period of maximum testis development from late June to the end of July the activity of males declined, as did body weight and scrota1 width. The pelage of intact males also deteriorated, while the female and castrated males remained sleek and maintained weight. The metabolic rate of intact males also declined after the breeding season, whereas that of the castrated males remained constant. Despite a decline in body weight, intact males showed an increase in energy consumption in July which remained high in August and September; faecal energy loss was lower in September than July. Energy consumption in castrated males did not increase until September, faecal energy loss did not change during the year. The differences observed among intact males, castrated males and females suggests that the male sex hormone system influences the metabolic and hormonal changes associated with male mortality.