Te Papa’s curator of terrestrial vertebrates Dr Colin Miskelly recently visited the Poor Knights Islands Nature Reserve, off the Northland coast, as part of a research team tracking the at-sea movements of Buller’s shearwaters. The project is led by Graeme Taylor of the Department of Conservation, and is intended to identify the marine environments used by these elegant seabirds, both when raising young and when on migration. Buller’s shearwaters breed only on the Poor Knights Islands, and migrate to the North Pacific after breeding.
The Poor Knights Islands are one of New Zealand’s least modified island groups. They are best known as New Zealand’s premier diving location, with the waters around the islands protected as a marine reserve. Few people, however, get the opportunity to step ashore, as the islands are protected as nature reserves, with access by permit only.
We visited Aorangi Island to study Buller’s shearwater (rako), a burrow-nesting seabird that breeds only on the Poor Knights Islands, but that migrates over much of the Pacific Ocean. Graeme Taylor and his co-workers had attached geolocation tags to the legs of about 30 shearwaters on previous visits, and our main task was to recapture these birds, so that the data could be downloaded from the tags to reveal where the birds had been. We also established permanent burrow plots on the island, as part of a project to estimate the size of the population.
Our visit was timed to be a few days after peak hatching of the Buller’s shearwaters’ eggs, when we hoped that both adults would be making frequent night-time visits to feed their single chick. The chicks are covered with dense down, and are left alone in their burrows when only a few days old, while both adults return to the sea to feed.
Several other seabird species also breed in burrows on the Poor Knights Islands, but most of these (including little penguin, fairy prion, fluttering shearwater, little shearwater and diving petrel) had finished rearing their young and had returned to sea. One exception was the rare Pycroft’s petrel, which we heard most nights. They also breed on a few other island groups off northern New Zealand, particularly in the Mercury Island group.
While Buller’s shearwaters dominated both the seabird and the nocturnal bird fauna, bellbirds (korimako) were by far the most common landbird, filling the forest with song from about 6 am each day. The bellbirds on the Poor Knights are considered a distinct subspecies from bellbirds elsewhere in New Zealand, differing slightly in colouration and measurements. Bellbirds are so abundant on the Poor Knights Islands that they exclude most other forest birds. We saw only a single fantail, and no tui, silvereyes, grey warblers or tomtits. It is likely that the bellbirds also prevent moreporks from establishing, as bellbirds mob moreporks, and there would be nowhere on the island for the owls to hide in the daytime.
After bellbirds, the most abundant landbirds on the island were red-crowned parakeets (kakariki), plus there were a few New Zealand pigeons (kukupa / kereru) feeding on ripe karaka fruit, and kingfishers (kotare) feeding on lizards, insects and crabs. Perhaps the most interesting of the landbirds was the secretive spotless crake (puweto). These small rails live in dense wetlands on the mainland, and so are rarely seen. In the absence of predators they venture into more open habitats, occurring under open forest on the Poor Knights Islands.
Life through a burrowscope lens (Part 2) – subterranean Poor Knights Islands
Night life on the Poor Knights Islands
Reptiles of the Poor Knights Islands
Critters of the Poor Knights Islands