Living in the Shadow of an Apex Predator: Asymmetrical Impacts on Ground Beetle (Coleoptera: Carabidae) Community Structure by Tuatara on Takapourewa, New Zealand

In Aotearoa/New Zealand, islands often act as refuges for rare invertebrate species, due to their lack of introduced predators. However, loss of invertebrate habitat and changes in densities of native predators can drive changes in community composition. On Takapourewa/Stephens Island, an island in Cook Strait, tuatara, a predatory reptile, have their highest densities in Aotearoa/New Zealand. Here, a tuatara exclusion fence built to protect native frogs also presents an opportunity to investigate effects on the ground beetle community. I trialled two different monitoring methods (use of artificial cover objects and pitfall traps) over 1 year to investigate best practice for monitoring ground beetles on Takapourewa. I used mark‐recapture methodology each month to assess the optimal timing for monitoring of two endangered ground beetles. I found that artificial cover objects were superior to pitfall traps for monitoring the ground beetle community. My surveys found significant impacts on both endangered species from tuatara. Asymmetrical predation of the ground beetle species suggests that differences in prey mobility have led to a change in carabid community composition. The fenced reserve intended to protect native frogs also acts as an effective conservation tool for rare ground beetles.