Torpor and reproduction in mammals are widely viewed as mutually exclusive processes. For most mammals, different energetic and hormonal demands appear to require a temporal sequence of torpor and reproduction within the yearly schedule. Torpor is charecterised by a pronounced fall in body temperature and metabolic rate, which results in an overall reduction of energy expenditure (Geiser and Ruf 1995) and in most mammals occurs during the non-reproductive season (Goldman et al. 1986; Barnes 1996). Reproduction, on the other hand, requires an increase of energy expenditure for acquiring, processing and transfer of nutrients to the growing offspring (Hoffman 1964; Goldman et al. 1986; Thompson and Nicoll 1986; Kenagy et al. 1989; Barnes 1996).