The endemic fauna of New Zealand evolved in the absence of mammalian predators and their introduction has been devastating. Large-scale aerial applications of cereal baits containing sodium fluoroacetate (1080) are routinely used to control these pests. During one such operation in the Blue Mountains, West Otago, trail cameras were used to monitor the impact of the application on mammalian predators.
Studies of waterfowl productivity at the Pukepuke Lagoon Wildlife Management Reserve have shown high mortality amongst young ducklings. This has been found in other studies in which it has often been attributed to predation. (Evans and Wolfe 1967, Balser et al. 1968, Urban 1970, Schranck 1972). Areas of pasture, cut-over pine forest, and dunes outside the reserve were also included in the trapping area.
In Britain, the use of "second-generation'' rodenticides has become widespread on agricultural premises. The high toxicity and relatively long half-lives of these compounds has raised concerns over potential secondary exposure and poisoning of non-target predators. Over the last 15 years, exposure has been extensively documented in the barn owl Tyto alba but relatively little is known about mammalian terrestrial predators.
A poison baiting operation at Trounson Kauri Park in Northland, New Zealand using first 1080 and then brodifacoum targeted possums (Trichosurus vulpecula) and rodents (Rattus rattus, Rattus norvegicus and Mus musculus). Predatory mammals were monitored by radio telemetry during the operation. All six feral cats (Felis catus), the single stoat (Mustela erminea) and the single ferret (Mustela furo) being monitored at the beginning of the operation died of secondary poisoning following the 1080 operation.
Populations of four species of carnivores were sampled over the five years 1983-87 at Pureora Forest Park, by regular three- monthly Fenn trap index lines supplemented with occasional control campaigns by shooting and additional traps. Stoats were the most frequently collected (63 captures), followed by weasels (18), cats (15) and ferrets (13). Stoats ranged throughout the mosaic of forest types but especially the older exotic blocks, hunting rabbits, rats, possums and birds. The mean age of 55 stoats trapped was 15 months, and their maximum life span about 5 years.
We studied the ecology of a high-density population of stoats in Fiordland, New Zealand, in the summer and autumn of 1990-91 following a Nothofagus seeding in 1990. Results are compared with findings from the same area in 1991-92, a period of lower stoat density. In the high-density year, minimum home ranges (revealed by radio-tracking) of four females averaged 69 ha and those of three males 93 ha; range lengths averaged 1.3 km and 2.5 km respectively. Neither difference was statistically significant.