Testing the efficacy of typical urban pest mammal control in two BACI experiments

Introduced mammalian predators have had dramatic impacts on the ecosystems of oceanic islands. While conservation strategies have been developed to suppress or eradicate them in a wide range of unpopulated habitats, their management in human-dominated landscapes is less advanced. Here, we assess the efficacy of urban predator control using two years (four sessions) of mammal monitoring data in before-after control-impact (BACI) experiments in Ōtepoti Dunedin and Kirikiriroa Hamilton. Results of the two BACI experiments provided no evidence for an effect of intensified predator control on rat, mouse, or possum abundance. Short experimental timeframes and low rat numbers in the before condition (especially for rats at non-treatment sites) may have made it difficult to identify effects. Further research is required to understand relationships between urban predator control and pest mammal abundance, and how control may be optimised to maximise cost-effectiveness.