Mice were likely introduced to South Georgia by early sealing expeditions and are known from two areas on south-western coast. Elsewhere, mice are known have significant impacts on ecosystems including predating birds and eggs, inhibiting plant regeneration by eating seeds and seedlings and affecting soil processes by predating invertebrates. Although, population densities on South Georgia are likely to be low, and the impacts limited, with on-going climate change there is potential for populations to grow and spread, potentially causing significant harm to native species.
As part of the South Georgia Heritage Trust project to eradicate rats from the island, as part of the phase II operation, an attempt was made to eradicate mice. To take into account the biology and feeding ecology of mice, the bait pellet size, active ingredient concentration and density at which it was spread was tailored for maximum chances of success. The baited area was over 49 ha, meaning this is the largest mouse eradication ever attempted.
Relevant documents including information on field trials and mouse ID can be found here.