Proceedings of the Vertebrate Pest Conference

The brushtail possum, a marsupial native to Australia, was widely introduced in New Zealand (NZ) to develop a fur industry. Before the settlement of humans in NZ, there were no terrestrial mammals; therefore, the local species evolved without mammalian predators. This resulted in native species populations declining at alarming rates and many possibly facing extinction on the NZ mainland, especially large-bodied endemic birds. In response to this problem, private investors (supported by the NZ government) developed an initiative to eradicate key mammal predators (possums, rats, and stoats) on the NZ mainland by 2050 (PFNZ2050). As a result, control efforts have significantly expanded over the past decade, and there are now 17 PFNZ2050 landscape projects covering 757,000 ha. Research has looked at combining audio, visual and social lures to improve control efforts for possums. Early results indicate that a combination of lures increases both encounter and interaction rates around control devices. In particular, the combination of audio and visual lures was consistently the top performer in both captive and small-scale field trials. Large-scale field trials are currently underway to confirm these initial results, investigating the effectiveness of combination lures paired with multi-kill AT220 possum traps. Additionally, the lures are being assessed at different times of the year and with varying possum densities. With the drive to PFNZ2050, pest mammal monitoring has markedly increased as researchers attempt to evaluate competing management control strategies. Traditionally, this has relied on single-use plastic monitoring devices such as chewcards and tracking tunnels. An investigation of pest-animal interaction with chewcards indicates that approximately 12% of plastic deployed ends up as microplastic pollution. Another NZ government initiative seeks to ban all single-use plastics, and research is currently investigating the efficacy of non-plastic (biodegradable) alternatives. This research also includes a cost-effectiveness analysis and the reliability of identifying animal bite marks on both plastic and non-plastic chewcards.