Potential of repellents for control of predation by mustelids, rats and possums in New Zealand B. Kay Clapperton 56 Margaret Avenue, Havelock North 4130, New Zealand Email:
[email protected] ~~~~~~~~~~~~~~~~~~~~ Dr B K Clapperton Wildlife Scientist & Editor Abstract To achieve widespread control of rats (Rattus rattus, R. norvegicus), stoats (Mustela erminea) and other mustelids, and brushtail possums (Trichosurus vulpecula) in New Zealand, we need to utilise as many combinations of control strategies as possible. Repellents could be used in island/border protection, push-pull strategies for protection of specific sites, to re-direct foraging behaviour or even in mating disruption. I review the recent literature to identify potential primary and secondary chemical repellents and briefly assess the options for auditory, visual and mechanical repellent devices. Chemical repellents include predator odours from urine, body and fur, as well as alarm pheromones and specific glandular secretions. While these odours can induce defensive behaviours, odours from familiar predators have not been shown to be effective repellents in field applications. It is not clear whether this lack of response is concentration- dependent. Odours from non-familiar as well as familiar predator sources may be worth investigating, including fear-inducing urinary compounds from large felines and mustelids. Identified active components of predator odours, including 2,5-dihydro-2,4,5-trimethylthiazoline, pyrazines, pyridines, 2-phenylethylamine, butanoic and butyric acids should be assessed as repellents for pest species in New Zealand, as should 4-methylpentanal and hexanal from rat alarm pheromones. Repellents can also be sourced from plant secondary metabolites and innately irritant or obnoxious odours.