Reproduction and growth in house mice from cold, hot and thermally moderate environments

The house mouse ('Mus domesticus') is found throughout Australia, and is successful in a wide range of climates. We examined the reproductive success and growth rate of young in differing thermal regimes (13°C, 'cold'; 22°C, 'control'; and 30°C, 'hot') in a laboratory colony of house mice derived from wild stock from Mudgee, New South Wales. Female mice in all groups did not always have a post-partum litter following the birth of their first litter, although post-partum litters were born in subsequent pairings. Litter sizes did not differ between treatment groups, although more young were born from post-partum matings. Young from the 'hot' group were smaller than for other groups, and their growth rates were slower. The observations on post-partum activity, and the differences in growth rates, may be of significance in explaining the sudden plague activities of mice in some parts of Australia.