The introduction of mammalian predators, particularly stoats (Mustela erminea), to New Zealand led to the decline in whio (Hymenolaimus malacorhynchos), an endemic riverine duck. Stoat control for whio in the South Island has focused on valley floor trapping along waterway margins but increasing survival and productivity for whio using this method is complicated by irruptive predator dynamics caused by occasional masting of beech species (Nothofagaceae).
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.