Homes for petrels - November 3rd

The most important part of Abi and Briggs’ work during this visit to Rangatira is opening up the Chatham petrel burrows. These birds are not doing so well, with only a few hundred pairs nesting on this island and a few more on Chatham Island itself. To keep tabs on the population, each Chatham petrel nest on Rangatira has been identified and replaced with an artificial burrow, with a pipe for the entrance and a wooden box to nest in.

The petrels arrive late in the season, and often in the past, they would arrive to find their burrows had been taken by broad-billed prions, which are slightly bigger and much more aggressive birds – easily capable of killing a Chatham petrel. DOC rangers block off the entrances to the petrel burrows until a week before the petrels are due to arrive on the island.

The entrance to each nest box is also covered with a neoprene “excluder,” with a small slit in it. Seabirds become “imprinted” on their burrows – which means they remember their exact location, even though they may be away at sea for years before coming back to breed. They somehow manage to drop through the forest canopy just a few metres from their burrows every time. I’ve been told that Taiko, another endangered petrel, has such amazing night navigation that it can sweep straight in from the sea and in through the door of its nest without pause, just folding its wings in at the last second. The excluder doesn’t stop the bird’s entry to the burrow; it just makes it more difficult so that only the birds who own that nest, who have imprinted on that particular burrow, will try to push through. The prions are just looking for an easy place to lay their eggs – they like to avoid digging new burrows - and when faced with the excluder they will not try hard enough to get inside.

Abi and Briggs spend days unblocking the petrel burrows and cleaning out last year’s nesting material – plus hundreds of wetas, and the odd really big spider. When you bring wetas into daylight, they have a nasty habit of leaping for nearest dark spot, diving down sleeves, collars, into packs or straight back into the nest box. Last job of the day? Finding all the six-legged passengers that have hidden themselves in your pockets, socks, hood and hair! Don’t bring them into the hut!

To learn more about the Department of Conservation's work with the Chatham petrel follow this link: http://www.doc.govt.nz/conservation/native-animals/birds/sea-and-shore-birds/chatham-petrel-ranguru/