Spatio-temporal patterns of introduced mice and invertebrates on Antipodes Island

Abstract

House mice (Mus musculus) are a widespread introduced species with major but often overlooked impacts on ecosystems, proportionally greater when they are the only introduced mammal present. Studies conducted on the ecology of mice on Antipodes Island, where they are the only introduced mammal, are presented and compared to previous work over the past four decades. Mice live-trapped on grids were more abundant in dense coastal tussock (147 mice/ha) compared to inland plateau grasslands (59 mice/ha), with a significant effect of age, but not sex, on both capture probability and range size. Body-size of mice has not changed over four decades, providing no evidence of gigantism, which on other Southern Ocean islands has been speculated to increase the predation risk to birds. Over 2,405 invertebrates from fourteen Orders were identified from pitfall traps and litter samples across five sites. Differences in invertebrate communities and taxonomic units attributable to habitat and altitude were detected among sites in both pitfall and litter samples on Antipodes Island. Differences in invertebrate communities were detected from litter samples on a neighbouring mouse-free island, with significantly greater abundance of large Amphipods and Collembola, but fewer Spiders. These data on introduced mouse ecology and invertebrate distribution on Antipodes Island contribute to the body of knowledge on Southern Ocean islands.