Investigator disturbance does not reduce annual breeding success or lifetime reproductive success in a vulnerable long-lived species, the yellow-eyed penguin

Well-studied, long-lived species, such as seabirds, can be exposed to decades of investigator interventions, and if the species is of conservation concern, intensive monitoring and management as well. Most evaluations of impacts of investigator disturbance have been relatively short-term. We evaluated both short- and long-term impacts of investigator disturbance on the yellow-eyed penguin (Megadyptes antipodes) by focusing on both the breeding season during which the impact occurred and lifetime reproductive success (LRS). In long-lived species, reproductive decisions are often trade-offs between current and future reproductive success, and lifetime reproductive success (LRS) can be influenced by many life- history and environmental parameters, including investigator disturbance. Yellow-eyed penguins, a long-lived seabird that has been intensively studied on the Otago Peninsula of South Island, New Zealand for three decades, are known to be vulnerable to human intrusion. Research and monitoring has required banding and band maintenance, handling, blood sampling, stomach flushing, and device deployment. We found no negative effects associated with any investigator disturbance type on breeding success or LRS. Monitoring disturbances (egg, chick and adult handling, band maintenance) that occurred during the egg and chick phases showed a positive association with breeding success and LRS, probably because the longer a nest survived the more likely eggs, chicks, or adults would be handled. There appeared to be a core of resilient individuals with long lifespans and high LRS that may buffer the population despite being exposed to many investigator disturbance events.