INVESTIGATING FACTORS DRIVING BREEDING SUCCESS, PHENOLOGY, BREEDING DISPERSAL, AND PAIR-BREEDING DYNAMICS OF THE TOUTOUWAI (NORTH ISLAND ROBIN; PETROICA LONGIPES)

The survival of any species requires robust and productive breeding within populations. Understanding the breeding biology of at-risk species can not only inform conservation management options, but also contextualise our understanding of fundamental biological processes and their evolution, such as phenology. Long-term study populations enable the investigation of such processes, that may occur or fluctuate over time. In this study, I investigate several aspects of the breeding biology of toutouwai (North Island robin; Petroica longipes), using 10 years of population monitoring data from a subsection of the Zealandia Ecosanctuary population. Specifically, I investigate 1) the relationship between weather and breeding season phenology, 2) pair-bond dynamics in the context of breeding success, 3) breeding dispersal dynamics in the context of breeding success and pair-retention, 4) spatial and temporal patterns of breeding success, and 5) potential factors driving breeding outcomes. In this population of toutouwai, breeding season duration is limited by low temperatures and low rainfall. Between breeding seasons, pair retention is much lower than within seasons, and likely driven by winter mortality and dispersal. The outcome of a nest has no significant relationship with the likelihood of subsequent divorce, though there is a tendency for failure to encourage divorce both between and within breeding seasons. Spatially, there were clear differences in breeding success across space. Temporally, success peaked in the middle of the breeding season for both nestling and fledgling-provisioning phases. Long-term, breeding phase outcomes did not change across the duration of the long-term study. Finally, when investigating a range of life history and environmental parameters that may influence breeding phase outcomes, no significant factors were identified. Reassuringly, the absence of any driving factors suggests that toutouwai in this population breed stably and productively. However, the potential influence of these factors should not be taken for granted with respect to other toutouwai populations. For example, the constraints weather places on breeding activity may be indicative of limitations on breeding success at thresholds simply not observed in the Zealandia Ecosanctuary region. Overall, this study captured novel insights into the breeding phenology, breeding dispersal, and spatial and temporal trends in breeding success in toutouwai, with the potential to inform conservation management practices.