surveillance

Managers of ecosanctuaries often need to make decisions in the face of uncertainty. Model-based tools which aim to assist this process, for example proof-of-absence models, are underpinned by assumptions about the behaviour of target animals, including their spatial movements. In some cases, however, there are few empirical data to draw on to inform these models. The movement behaviour of individual pests in low-density environments, as well as the dispersal of juveniles away from their natal location, is poorly understood for many species, including the ship rat (Rattus rattus).

Dispersal is a fundamentally important aspect of animal behaviour, but empirical data describing it are lacking for many species. Here, we report on a field study aimed at measuring post-weaning movement distances of juvenile ship rats (Rattus rattus) and their mother away from a known natal nest site in an area with low conspecific population density. The movement behaviour of invasive species at low density is of particular interest, as it can inform design of surveillance arrays to detect incursion into predator-free areas.

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.