Invasive ship rats (Rattus rattus) pose a threat to the biota of Goat Island (9.3 ha), New Zealand. In June 2016 we installed 10 Goodnature A24 CO2 powered self-resetting rat and stoat traps equipped with digital strike counters (Goodnature Ltd., Wellington, NZ) to control rat numbers on the island. The self-resetting traps were monitored with motion-activated cameras to develop a measure of rat abundance from camera traps. All devices were checked on 10 occasions from August 2016 to October 2017. The videos revealed high rat activity on the island, which reduced over time.
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.
Squamata are one of the most threatened groups among island vertebrates, facing high pressure from exotic species. However, the contribution of small terrestrial reptiles in invasive rodents’ diet remains poorly investigated, partly because of the lack of tools for accurately identifying chewed prey fragments in gut contents. The New Caledonia archipelago (South Pacific) hosts an exceptional terrestrial squamata fauna (105 species, 91.6% endemic) that are faced with many invasive species (rodents, feral cats, feral pigs, ants) and strong human pressures.
Big South Cape Island (Taukihepa) is a 1040 ha island, 1.5 km from the southwest coast of Stewart Island/Rakiura, New Zealand. This island was rat-free until the incursion of ship rats (Rattus rattus) in, or shortly before, 1963, suspected to have been accidentally introduced via local fishing boats that moored at the island with ropes to the shore, and were used to transport the mutton birders to the island.