Seasonal changes in age class structure and reproductive status of house mice on Marion Island (sub-Antarctic)

摘要: Feral house mice on sub-Antarctic Marion Island become reproductively active (males scrotal, females with perforate vaginas or pregnant) at an age >60 days and breed until death, which may occur more than 13 months. Breeding is strongly seasonal; pregnant lactating were found only from October to May. A substantial proportion of old enough in one summer overwinters form a significant component the breeding population following but it unlikely that any survive second winter. The onset closely synchronized increasing day length occurs about 2 months before mean temperature ground surface starts increase significantly. Cessation associated declining temperatures late summer. For both males females, best correlation between reproductive activity parameters measured was average maximum 1 cm above ground. Competition for macroinvertebrate prey increases sharply early winter due high mouse numbers. season 1991/1992 1992/1993 least longer 1979/1980, because started earlier, stopped later, 1991/1993. later cessation 1991/1993 despite fact there greater competition prey, air during lower, 1979/1980.