Population biology of house mice (Mus musculus L.) on sub-Antarctic Marion Island

Abstract

Based on mark-recapture models, house mouse densities on sub-Antarctic Marion Island changed seasonally (up to 10-fold) and differed between habitats. Peak densities occurred towards the end of summer (May). On both the hummocky beach and vegetated lava study grids, densities at the end of summer were significantly higher than those recorded during 1979/80. During the rest of the year densities were significantly lower on these study grids than those recorded during 1979/80. Length of the breeding season (6,5 months) and mean litter size (7,24 ± 1,7) were of the same order as those recorded during 1979/80, as were age and sex specific mortality patterns. The incidence of pregnancy (7,27 litters/season) was higher (not significant) than that recorded during 1979/80. Prenatal mortality was positively correlated with ovulation rate. Differences in annual trends may result from yearly changes in environmental conditions and do not support speculation that these may have resulted from medium-term changes in climatic conditions in the sub-Antarctic.