Cook's Petrel on the Barrier
Not such a good island to nest on...
by John Ogden

On April 12th I got a call from Amelia Geary at the Department of Conservation. Amelia is the new Biodiversity Ranger, replacing Halema. A Cook’s Petrel with some downy back feathers – thus a juvenile which must have been born on the island – had been reported from Okupu, where it had stunned itself flying into Julie Bowers-Rakatu’s glass door. Julie had it in a box at Claris store and did I want to see it? I said yes. Sure enough it was exactly as reported. I took some photos – that’s it above being held by Amelia. Once fed with micro-waved pilchard it seemed happy enough so it went back into its box to be released at Okupu on dark.

Back in 2008 (Environmental News 13) we reported Cook’s petrels being killed, probably by a cat, at Tryphena. Once on the ground these seabirds are not very agile, and make easy prey for cats. Cook’s Petrels are increasing on Little Barrier following feral cat and rat eradication there in 2004, and the increasing number of dead ones on Great Barrier (See Graph above) might represent new colonists attempting to breed. Although there are still a few Cook’s petrels nesting on Hirakimata (Mt. Hobson) and elsewhere, Julie’s juvenile is the first real evidence of fledging on Great Barrier for some years. Cook’s petrels nest in burrows, which they visit only after dark; they can often be heard (“ke ke kek, ke ke kek”) in summer as they fly over the island at night on their way to their main nesting colony on Little Barrier. Despite the increase on Little Barrier, overall the species is regarded as ‘declining’. The Little Barrier evidence clearly shows that rats were the main cause of the decline there. Biz Bell reports that in 2009-10, four Cook’s petrel chicks in burrows on Hirakimata were all dragged out and eaten by rats in one night. That is the sad reality of continuing biodiversity loss on this island.