BODY-TEMPERATURE RHYTHMS AND ACTIVITY IN REPRODUCTIVE ANTECHINUS (MARSUPIALIA)

To determine whether locomotor activity and body temperature (T-b) rhy thms change during the mating season of male Antechinus stuartii and w hether that could contribute to postmating die-off, we measured both v ariables in individuals kept in the laboratory under natural photoperi od. Before the mating season Antechinus were mainly nocturnal. However , during the mating period (end of August) males showed a markedly ele vated activity level and some animals extended their activity period w ell into the light phase. After about 2 weeks, normal activity pattern s were restored. Activity was always accompanied by elevated T(b)s, wh ereas resting phases were characterized by low T(b)s. During the matin g season the average daily T-b was increased because animals maintaine d high T(b)s for longer time periods and because the resting T-b was a lso elevated. The rise of both T-b and locomotor activity during the m ating season indicate an enhanced energy expenditure even when agonist ic encounters between males and mating are excluded. However, under la boratory conditions without severe cold stress, food ad lib, and witho ut social interaction males were able to avert postmating die-off.