Ambury Park: Birdlife rises from sea of waste

Spoonbills feeding in the Manukau Harbour between Ambury Regional Park and Puketutu Island. Photo / Martin Sykes

Beauty abounds where once there was sewage and sludge, finds Liz Light.

Grumble, grump, Auckland weather. The forecast was good, I left home in brilliant sunshine, but now it's raining. The Manukau Harbour is dull grey, Puketutu Island a shadow in the gloom and I don't feel excited about a walk buffeted by Mangere's west wind.

When the rain turns to spit and Puketutu Island is clearer, my spirits lift. Laura, my niece, and I have arranged for her car to be at one end of Ambury Regional Park and mine at the other so we can complete the Watercare Coastal Walkway without backtracking.

We leave Island Rd and walk north along the coast. Behind a high fence, not yet hidden by recently planted trees, the industrial complex of Watercare's sewage treatment plant is humming, turning a million people's sewage into pure water and garden compost.

The decommissioning of 500ha of oxidation ponds, restoration of 13km of shoreline, construction of beaches for birds and planting of 27,000 trees was part of the $450 million upgrade of Watercare's now environmentally friendly sewage conversion site. This was New Zealand's largest coastal restoration project, officially completed in 2005, but the harbour and land is still slowly healing.

The trees are small, but birds are abundant and the presence of plenty of water and wading birds is a sign of a healthy, food-filled harbour. Kingfishers sit in high places watching for moving things and, on the rocks, waiting for the tide to recede, I see two white-faced herons and a couple of gulls. I'm crazy about birds and happy to see the herons, self-introduced from Australia 50 years ago and now numerous.

The suns lights up a colony of royal spoonbills on a shell bank - hundreds of them - bright white with black legs and long, black, spoon-shaped beaks. Most are standing on one leg with their heads twisted around 180 degrees and their beaks tucked into the feathers on their backs. Between the spoonbill colony and the path are flocks of pied stilts and godwits which take fright when a couple of cyclists pass by. As one, they swoop in wide circles, then settle on the mudflats again. The spoonbills stay asleep throughout the fluttering kerfuffle.

The path veers inland past a basin of densely green foliage. This low-lying area was used as a sewage sludge dump and now, with their roots sucking up old poo, the new native plants are growing extraordinarily well.

There is still a whiff of the area's past life but the birds don't mind and, from a hide, we watch herons and gulls picking food from tidal mud. Shags sit on rocks, heads held high and wings stretched wide.

We walk inland again and find thousands of pied oystercatchers, mostly in the one-legged sleeping position, standing in a wide, flat paddock, along with a few pukeko and a gathering of black swans in front of the houses of suburban Mangere and the volcanic cone of Mangere Mountain.

The mountain erupted 18,000 years ago and this part of Ambury Regional Park sits on top of a vast lava field made fertile by volcanic ash. The mountain once housed a large, fortified Maori town and there are 95 archaeological sites in the park. This area is a joy for geologists, who claim Mangere Mountain is the largest and best-preserved of Auckland's 48 volcanoes, and they rave about the lava formations to be seen.

I poke a piece of honeycombed black rock, but my interest is with birds, not rocks, and today's walk has been brilliant.

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Further information: Ambury Regional Park is on the edge of Manukau Harbour, 2km from Mangere Bridge. It's a working farm, so is a great place for city kids to get close to sheep, cows, pigs, hens and horses. It has an educational centre and is rich in volcanic, Maori and European settlement history. Above all, Ambury is a birdwatchers' paradise.

See arc.govt.nz for more on Auckland Regional Parks.