Demography in Island and Mainland Populations of the Feral House Mouse, Mus musculus molossinus

Abstract

The reproduction and longevity of the feral house mouse, Mus musculus molossinus, were compared between an island (Saku Island, Mikawa Bay, Aichi Prefecture) and the mainland (Kasugai and Nagoya Cities, Aichi Prefecture) . As compared with the mainland populations, the island mice showed the following characteristics: 1) No spring reproduction. 2) Delayed maturation of females; in particular, females born after January would not produce young until the following autumn. 3) Low proportion of fertile males and pregnant or lactating females. 4) Skewness toward old ages of females participating in reproduction; this is especially conspicuous in autumn. 5) A similarity in number of embryos. 6) Great longevity of adults. 7) About equal mortality in young (the age group 0) . 8) Light wounding. Most of these parameters indicate that the island mice are K-selected, which selection seems to favor lower reproduction and greater longevity for Saku Island mice.