Body temperature rhythms and activity in reproductive Antechinus (Marsupialia).

To determine whether locomotor activity and body temperature (Tb) rhythms change during the mating season of male Antechinus stuartii and whether that could contribute to postmating die-off, we measured both variables in individuals kept in the laboratory under natural photoperiod. Before the mating season Antechinus were mainly nocturnal. However, during the mating period (end of August) males showed a markedly elevated activity level and some animals extended their activity period well into the light phase. After about 2 weeks, normal activity patterns were restored. Activity was always accompanied by elevated TbS, whereas resting phases were characterized by low TbS. During the mating season the average daily Tb was increased because animals maintained high TbS for longer time periods and because the resting Tb was also elevated. The rise of both Tb and locomotor activity during the mating season indicate an enhanced energy expenditure even when agonistic encounters between males and mating are excluded. However, under laboratory conditions without severe cold stress, food ad lib, and without social interaction males were able to avert postmating die-off.