Life through a burrowscope lens (Part 2) – subterranean Poor Knights Islands

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. They breed in rock crevices or in burrows that they excavate in soil. Here, Colin describes some of the wildlife they share their subterranean homes with.

An adult Buller's shearwater on Aorangi Island, Poor Knights Islands Nature Reserve. Image: Colin Miskelly, Te Papa — An adult Buller’s shearwater on Aorangi Island, Poor Knights Islands Nature Reserve. Image: Colin Miskelly, Te Papa

A burrowscope is a field-hardened endoscope on steroids, used to view the interior of burrows. It can be used to determine whether a burrow is occupied or vacant, to identify what species is in a burrow, and to provide information on breeding success. At least seven species of seabirds excavate or breed in burrows and rock crevices on the Poor Knights Islands, and many other animals also inhabit the thousands of burrows there.

Buller's shearwater burrows on Oneho hill, Aorangi Island, Poor Knights Islands Nature Reserve. Image: Colin Miskelly, Te Papa — Buller’s shearwater burrows on Oneho hill, Aorangi Island, Poor Knights Islands Nature Reserve. Image: Colin Miskelly, Te Papa

The following images show some of the secrets of underground life on this pest-free nature reserve. During our visit (late January to early February), most of the breeding seabird species had finished breeding, but the Buller’s shearwaters had recently hatched their eggs.

An adult Buller's shearwater inside its burrow, viewed through a burrowscope. Image: Colin Miskelly, Te Papa — An adult Buller’s shearwater inside its burrow, viewed through a burrowscope. Image: Colin Miskelly, Te Papa

Buller’s shearwater egg viewed through a burrowscope. Image: Colin Miskelly, Te Papa

Buller’s shearwater chick inside its burrow, viewed through a burrowscope. Image: Colin Miskelly, Te Papa

Several species of reptiles live in burrows on the Poor Knights Islands, including tuatara, which occasionally kill and eat shearwater chicks. The smaller skinks and geckos usually move rapidly away from the light cast by the burrowscope, and rarely pose long enough for a photograph to be taken.

Tuatara inside a shearwater burrow on Aorangi Island, as viewed through a burrowscope. Image: Colin Miskelly, Te Papa

A marbled skink (the dark shape on the right) inside a shearwater burrow on Aorangi Island, as viewed through a burrowscope. Image: Colin Miskelly, Te Papa

Duvaucel's gecko inside a shearwater burrow on Aorangi Island, as viewed through a burrowscope. Image: Colin Miskelly, Te Papa — Duvaucel’s gecko inside a shearwater burrow on Aorangi Island, as viewed through a burrowscope. Image: Colin Miskelly, Te Papa

Flax snails hide in seabird burrows and under rocks during the day, emerging on damp nights to graze on fallen leaves.

Flax snail (Placostylus hongii) inside a shearwater burrow on Aorangi Island, as viewed through a burrowscope. Image: Colin Miskelly, Te Papa — Flax snail (*Placostylus hongii*) inside a shearwater burrow on Aorangi Island, as viewed through a burrowscope. Image: Colin Miskelly, Te Papa

In addition to many seabird species, some landbirds also nest in burrows. We found a kingfisher nest in a low bank, with the entrance only 20 cm above the forest floor. The two large chicks inside froze statue-like when the burrowscope was inserted into their hole.