Strategies for detection of house mice on a recently invaded island

Invasive rodents pose a grave and persistent threat to New Zealand’s native biodiversity. Rodent eradication is a successful conservation tool on islands. However, eradications may fail, and there is always potential for reinvasion. It is therefore essential that effective systems are in place for the early detection of rodents in the case of eradication failure or reincursion. We used data from a small New Zealand island experimentally colonised with house mice (Mus musculus) to investigate the effectiveness of selected mammal surveillance practices, including detection device choice, duration of deployment period, and device placement. The effect of population density on mouse detectability was assessed using population abundance estimates made regularly throughout the experimental island colonisation. We found that commonly used detection practices were highly effective for the detection of mice, even at low population density.