Determining burrow occupancy, fledging success and land‐based threats to mainland and near‐shore island sooty shearwater (Puffinus griseus) colonies

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Abstract
A specialised infra‐red camera “burrowscope” was used to determine the burrow occupancy rate of sooty shearwaters at three Nugget Point colonies, two Taiaroa Head colonies and one Tuhawaiki Island colony in 1992/93, and the results compared to those given by less reliable methods. At three Nugget Point colonies, fledging success ranged from 0–41%. One of these colonies also suffered high mortality of adults, most likely attributable to mammalian predation, during the nest preparation and egg‐laying period. At the Taiaroa Head and Tuhawaiki Island colonies, low predator abundance may have been an important factor contributing to the high fledging success (64–100%). Several years of monitoring reproductive and survival parameters are needed to verify the status of mainland colonies and the impacts of various possible threats to their survival and productivity.