Implications of visitations by Shore Skinks Oligosoma smithi to bait stations containing brodifacoum in a dune system in New Zealand

Abstract

Brodifacoum is a highly toxic, second-generation anticoagulant developed for the control of rodent pests. However, information regarding the impacts of brodifacoum on non-target wildlife has been largely collected opportunistically and is generally avian biased. Reviews of non-target impacts of brodifacoum routinely regard reptiles and amphibians as low risk, despite there being no formal evidence supporting this assumption. Recent evidence suggests that some native lizard species will consume cereal baits in addition to toxin-loaded invertebrates. As part of a wider study, we quantified visitation rates to brodifacoum bait stations by Shore Skinks Oligosoma smithi, and recorded the first observation of this species consuming toxic bait. Bait stations (n = 56) recorded up to 81.5% tracking incidence by Shore Skinks across one of two pest-controlled grids. Skinks were occasionally observed inside bait stations feeding on invertebrates. Of the 805 skinks caught in pitfall traps over the 6 month period, none showed clinical or behavioural signs of anticoagulant toxicosis. Further research into the acute toxicity and chronic sub-lethal impacts of pesticides on herpetofauna is required before potential impacts on these fauna can be dismissed.