Know your enemy? Conservation management causes loss of antipredator behaviour to novel predators in New Zealand robins

Abstract

While studies of animal behaviour have performed a key role in informing conservation management of threatened species, antipredator behaviours are rarely considered in conservation decision making. This study assessed the impact of the translocation of an endemic New Zealand bird to a predator-free ecosanctuary on its antipredator behaviour. We compared antipredator responses of South Island robins, Petroica australis australis, found inside the ecosanctuary with those of robins inhabiting local predator-dense forests, using taxidermy models of a rat, Rattus norvegicus, and stoat, Mustela erminea. Although mammalian predators are relatively novel in New Zealand, some endemic species such as South Island robins recognize them and show antipredator behaviours. We determined the rate of loss of behaviours after release into the ecosanctuary since founders were translocated from predator-dense environments. Robins inhabiting the ecosanctuary exhibited lower intensities of antipredator behaviour towards the model rat than robins in predator-dense areas within at least 3 years after translocation, a shorter period than previously suggested. A recent stoat incursion in the sanctuary provided the opportunity to discern whether robins regained predator-specific antipredator behaviours or displayed heightened generic vigilance to all novel predators. The more intense antipredator responses recorded towards the model stoat than the model rat within the ecosanctuary indicated that the robins had regained their behaviours towards stoats but had not generalized the predatory features of the stoat to the rat. Our study raises concerns regarding the viability of sanctuary populations as sources for future translocations into areas with predators. We recommend antipredator training to improve species survival.