Rangitāhua Kermadec Islands
Raoul Island is by far the largest of the Kermadec Group (2943ha), the next largest is Macauley Island (306ha). The most recent estimates place the seabird population of the group at 10-15 million birds, with the vast proportion of them breeding on Macauley, Curtis, Cheeseman and the Herald Island. The number of seabirds breeding on Raoul prior to first human arrivals is difficult to estimate with respect to both taxonomic diversity and total population size. It is most likely seabird populations would have been considerably larger than the estimates (c. 1.5 million birds) made in the early 20th Century. It is certain, however, that by the end of the 20th Century the island was almost totally devoid of seabirds owing to predation, harvesting and habitat loss following human arrival. Only sooty terns, a few white terns and red-tailed tropicbirds remained. The vast numbers of petrels and shearwaters were gone.
A long-term government commitment to pest-animal control has seen a reversal of these massive losses. First, goats were eliminated during 1972-1984, then Norway rats and feral cats were eradicated by DOC beginning in 2003. In the twenty years since, three species that formerly bred on the island have become established – black-winged petrel (breeding first confirmed 2006), Kermadec petrel (winter-breeding) (2007), wedge-tailed shearwater (2008) – along with two for which there are no historical records – Kermadec little shearwater (2015) and Kermadec storm-petrel (2017). Currently seabird species diversity stands at eight species, at the rate of one species per three years, although populations are still a fraction of those formerly breeding on the island. The key determinant in the recovery is the proximity of source populations on the Herald Islands, the closest only 2kms from Raoul Island, with Raoul providing fertile ground for recolonisation.
To witness the spectacle of seabirds massing over Macauley Island and the diminutive Meyer and Herald Islands close to Raoul is to appreciate why some islands, especially those that are truly oceanic and where seabirds dominate their ecology, can best be regarded as ‘seabird islands’. Seabirds provide conduits that link marine and terrestrial ecosystems, and seabird islands have many distinct emergent community and ecosystem properties.
The Seabird Trust is currently contributing to Te Mana o Rangitāhua, a collaborative project led by Ngāti Kuri who hold mana whenua over the islands, and the Auckland Museum. It is a holistic approach to transform ecosystem wellbeing, a five-year partnership with additional partners from several institutions and agencies.