The white-chinned petrel Procellaria aequinoctialis is one of the most frequently observed seabird species captured in fisheries bycatch, yet some populations remain virtually unstudied. In the New Zealand region, the priority programmes to fill key information gaps included surveying, tracking and collecting demographic data from white-chinned petrels in the Auckland Islands.
Survey of the Campbell Island population and clarification of taxonomic uncertainty in the New Zealand region were secondary aims. The scope of this report is to summarise research findings, with focus on New Zealand populations of white-chinned petrels.
An estimated 186,000 (95% CI: 131,000–248,000) white-chinned petrel pairs breed in the Auckland Islands, and the Campbell Island group supports around 22,000 (15,000–29,000) breeding pairs. The New Zealand region supports almost a third of white-chinned petrels globally, but population trends remain unknown. We establish population baselines that can be repeated for trend estimation.
A tracking programme in the Auckland Islands has retrieved 40 geolocators from white-chinned petrels, which were analysed together with tracking data from all major island populations. NZ populations do not overlap at sea with populations from South Atlantic or Indian Ocean islands. Antipodes and Auckland populations have some marine areas of overlap, but also have large areas specific to birds from a single island.
Global density estimates for white-chinned petrels show key global density hotspots (off South America, New Zealand, and southern Africa). A study was initiated to collect demographic data from white-chinned petrels at Adams Island, Auckland Islands. Four years of data have since been collected.
Genomic data revealed genetic structure in white-chinned petrels at very fine scale (among islands) and at broad oceanic scales (between Atlantic and Indian Ocean regions) that was not detected previously. Three ocean-basin scale evolutionarily significant units, ESUs, were identified. The NZ ESU contains Antipodes, Auckland and Campbell island populations. Some NZ island populations are sufficiently unique from others in the region to link mortality in a specific fishery to a given island.