A Cunning Trick May Fool Offspring

Forest and Bird, Issue 312, 1 May 2004, Page 8

A Cunning Trick May Fool Offspring

Origin Natural History Unit

—DAVE HANSFORD,

pioneering exercise in low-down deceit is approaching a moment of truth on Mana Island off the Wellington west coast. Fairy prion chicks from Stephens Island/Takapourewa in Cook Strait are being encouraged to think Mana Island is really their home. The theory is simple enough: take prion chicks from their burrows on Takapourewa before they’ve had a chance to call it home. Then fly them by helicopter to Mana, a Department of Conservation sanctuary off the Plimmerton coast north of Wellington, and place them in artificial burrows. Feed them, then hope that by the time they fly the nest, they've adopted it as their birthplace. At transfer time, the small

crowd is struck silent as the echo of Anaru Paul’s haka fades among the low hills of Mana Island. The only sound is a scuffling from one of the cardboard cat boxes at his feet. Inside are fairy prion chicks, perhaps six-weeks-old, plucked by Anaru Paul and some doughty helpers from natal burrows on the steep brown cliffs of Stephens Island. To that end Colin Miskelly, a DoC technical support manager, has left nothing to chance — right down to a handful of original nest material from Takapourewa being placed in each of the artificial burrows to give all the right olfactory cues. The prions are just the first intake in a long list of original inhabitants — birds, reptiles, insects — that DoC wants to

bring home to Mana as part of an ecological restoration plan. ‘Just how the chicks imprint on their home site is still fuzzy science, says Colin Miskelly. ‘It could be the landscape, the wind direction, smell or even magnetic fields. Experiments have shown (by the low-tech expedient of placing a matchstick at the mouth of each burrow) that nearly half of the chicks on Mana leave the burrow the very first time they venture to its entrance. Once they lift off into the Cook Strait northerly, their feet won't touch dry land for two or three years. The first batch of prion chicks — 40 of them — was brought to Mana in 2002. That means the acid test of Miskelly’s theory will be conducted this winter — around July or August — when he'll be anxiously scanning the skies for signs of his brood returning. ‘We’ve kept the bubbly on ice till then, he says. Just in case they still need some help, he’s placed an array of weatherproof loudspeakers along the cliff, playing the welcoming calls of their kind. Meanwhile, every day, a small army of surrogate parents put

water and sardines (Brunswick, not Chilean — they tested them both) in a blender and mix up a fetid, oily puree. Then they extract each of the 100 chicks, weigh them, and measure them, before syringing the ‘sardine smoothie’ into the chicks. Then they’re weighed again, to establish just how much food they’ve taken on board, and reconsigned to the darkness of the burrow. For Colin Miskelly, scaling vertical cliffs and rummaging in reeking nest burrows crawling with fleas is a kind of investment in the future. Fairy prions aren't endangered (there are an estimated one million pairs of them on Takapourewa alone) but that’s just the point. Colin Miskelly wants to practice these techniques on more common birds first before applying them to some of our critically threatened seabirds, like the Chatham Island taiko or magenta petrel (down to 15 breeding pairs), and the Chatham petrel. (See page 32 this issue.) If it works, this curious blend of animal psychology, husbandry and deception will be a world first.