The Kermadec storm petrel has been an enigma, only partly solved when a small breeding colony was discovered on the small and inaccessible Haszard Island in the Kermadec group in August 2006.

About 1890, storm petrels were said to be common at sea around the islands, and in 1907 two corpses were washed ashore on Raoul Island. In November 1925, 15 birds were shot at sea around the islands and from these the species was recognised as distinct and named. They were not recorded again until the 1960s and seen more frequently during the 1980s. Most of these records are close the Kermadec Islands but a group of 4 was seen 480 km off the Australian coast.

The inability to locate the breeding site led to the suggestion that they might be unusual Australian white-faced storm petrels rather than a distinct form, but the discovery of a colony of these distinctive birds has settled these doubts.

Identification

Kermadec storm petrels look like and fly like a white-faced storm petrel, differing only in their rump colour. They are grey above with dark-grey flight feathers and tail; the under-surfaces are white, and there is a broad white stripe above the eye. The bill and legs are black with yellow webs on the feet. Their main distinguishing mark is a prominent white, rather than grey, rump, a nearly square cut rather than forked tail when folded,  and there a little less grey on the sides of the breast. When feeding they move with the same high bounding hops as the white-faced storm petrel.

Voice: unknown

Similar species: the most distinctive field mark on Kermadec storm petrels, is the contrasting white rump, which the other ‘grey-backed’ storm petrels do not share. The white breast and front, and the bounding flight pattern further distinguish it from all other storm petrels except the white-faced storm petrel.

Distribution and habitat

Kermadec storm petrels are known to breed only on Haszard Island, offshore from Macauley Island, in the southern Kermadec Islands. Here, they burrow in friable soil under herbs and sedges.

At sea, Kermadec storm petrels are seen most often close to the island group, with other records up to 750 km from their breeding islands toward the Tasman Sea and New Zealand. There is also a single record off the Australian coast 2,500 km away. All records fall between May and November, and so it is likely that the birds migrate away from the Kermadec Islands for the rest of the year.

Population

Perhaps 100-300 pairs.

Threats and conservation

Most of the larger islands in the Kermadec group have had rats, cats and pigs, and these predators are the likely reasons why Kermadec storm petrels are now restricted to a small colony on an inaccessible rock. With the removal of all of these animals by the Department of Conservation it is hoped that Kermadec storm petrels can recolonise former breeding sites and numbers will increase again. At present their main threat seems likely to be the disturbance of nests and nesting birds by the larger and vastly more numerous black-winged petrels, little shearwaters and wedge-tailed shearwaters when they dig their nesting burrows.

Breeding         

Kermadec storm petrels are likely to breed as monogamous pairs in colonies. Their single egg is laid in August in a burrow in gritty soil.

Behaviour and ecology

Most of the records of Kermadec storm petrels at sea are close to seamount chains in deep water, and so they are probably highly pelagic birds favouring areas of upwelling like other storm petrels. In general their habits are likely to be similar to those of the closely related white-faced storm petrel.

Food

Unknown

References

Gaskin, C.P. 2011. Seabirds of the Kermadec region: their natural history and conservation. Science for Conservation 316, Department of Conservation, Wellington.

Imber, M.J.; Stephenson, B.M. 2008. Sightings and capture of Kermadec storm petrels (Pelagodroma marina albiclunis), off Haszard Island and the Meyer Islets, Kermadec Islands, in 2004. Notornis 55: 166-170.

Recommended citation

Southey, I. 2013. Kermadec storm petrel. In Miskelly, C.M. (ed.) New Zealand Birds Online. www.nzbirdsonline.org.nz