Coming Home to Roost

Forest and Bird, Issue 310, 1 November 2003, Page 38

Coming Home to Roost

DAVE HANSFORD

finds native birdlife is soreading beyond the Karori

Wildlife Sanctuary into the capital's suburbs.

fruits for a hungry brood. Saddleback fossick about in the leaf litter, chattering their insistent staccato. Robins and tomtits flit from trunk to trunk, gleaning insects from the leaves and lichens, and the blooming canopy is a whirl of whiteheads. As the shadows of dusk creep across the valley, kiwi call to one another through the frosty half-light. It’s a scene from a New Zealand of long ago, stolen from the mainland by possums, stoats, rats, cats, pigs, goats and deer. Yet this is not an offshore island. The kiwi are calling just four kilometres from Wellington’s Central Business District. The Karori Wildlife Sanctuary is an inspired vision. The idea was to take an old water reservoir and surround it with a fence that would keep out the legions of predators and browsers that have destroyed the forests elsewhere. A carefully considered programme of reintroductions is bringing the New Zealand forest of old back to the capital. Left to feed and breed in peace, the birds have exceeded all expectations. Last season, one pair of bellbirds raised 13 chicks. And a pair of falcons has moved in, a sure sign that an ecosystem is cranking up again. The Sanctuary has filled with birds so quickly that many have jumped the fence and spread into suburbia, to the delight of the neighbours. For now, the bird programme has slowed for staff to catch their breath and interpret I: the heart of Wellington, a kaka plucks

the fruits of their labours (though the release of red-crowned kakariki is planned, and the tomtits and bellbirds will be ‘topped up’). "We want to make sure we thoroughly

document the work that’s been done, says the Sanctuary conservation manager Raewyn Empson. ‘It was always an integral part of the plan. We want to learn as much as we can, even though we’re stretched to monitor the releases we’ve done so far. here’s still trouble in paradise. On the wall, in Empson’s chaotic office, is a photo of a mouse with its head between the mesh wires of a ‘pest-proof’ fence. Despite the best of research and development, mice are still breaching the Sanctuary. Rachel Empson thinks the fence is still a barrier to adult mice, but young animals — perhaps

Wellington personality Peter Bush was sitting down to lunch in his Island Bay garden, only to have his meal pinched by a kaka. And he didn’t mind a bit. The success of the Karori Wildlife Sanctuary has reunited Wellingtonians with old friends they thought were lost for good.

10 grams and under — are somehow able to squeeze through. The key, she thinks, is the depth of the animal’s skull. It’s the largest solid part of its body. If it can get that through, the rest will follow. ‘Their bodies can flatten out to the point where they can get through 6mm mesh, she says. One option being investigated is to reorient the fence’s rectangular mesh from vertical to horizontal. She says the mice may not think to turn their heads to one side to start squeezing through. Other options, include the addition of a solid sheet of cladding around the fence’s base, but trials will have to wait until next summer, when they can catch plenty of baby mice. For the time being, reptile reintroductions — including plans to bring tuatara home to the Wellington mainland — are on hold. The same goes for the large-bodied invertebrates — giant weta and speargrass weevil. ‘I think we'll eventually be able to stop the mice; the right fence is out there somewhere, says Rachel Empson. "But in the meantime, without any larger predators inside the Sanctuary, bird numbers are exploding, which is providing an interesting research project in itself. There’s no evidence of direct predation on eggs or chicks, but mice are known opportunists.

Other work goes on apace. Once permits are secured to use the fish toxin Rotenone, brown trout and a plague of perch will be eradicated from the lower of the Sanctuary’s two lakes, which have two distinct mixes of fauna. Once that’s done, the lakes will get the same treatment as the forest, says Empson. ‘We already have short-finned eel and banded kokopu; we want to introduce mudfish, other galaxiids, long-finned eel? When that happens, researchers from the Department of Conservation and Massey University will be watching closely, documenting the response of native freshwater fauna as the invaders are removed. Therein lies another of Karori Sanctuary’s great gifts. It’s a living laboratory, a test bed for valuable research in several disciplines. ‘What happens when we remove this? What happens when we add that?’ Currently there are four theses in progress on plants, six research projects on birds and two fish projects, plus the Sanctuary’s own monitoring work. Karori Sanctuary is pioneering techniques. People elsewhere with restoration plans are watching closely as Karori’s staff tackle and surmount problem after problem. ‘We've learnt an awful lot already, Rachel Empson says, ‘and the lessons will be really

valuable for other reserves and potential "mainland island" projects.’ In the meantime, ordinary Wellingtonians are just happy to see some old friends come home at last.