The city’s wastewater treatment ponds are an astonishing and profoundly important wildlife habitat, a Wellington biologist says.

Dr Murray Williams, a Department of Conservation (Te Papa Atawhai) waterfowl biologist, came to the city in late February to verify reports that shoveler ducks were moulting there.

Dr Williams is New Zealand’s foremost duck researcher. For more than 30 years he has been at the forefront of research into native and introduced waterfowl.

He was astonished to find these ducks moulting at the treatment ponds because the species is thought to have only four moulting sites in the whole country and no new sites had been found for 20 years.

“Being flightless for about six weeks the birds are very vulnerable to predators and fearful of human interference,” Dr Williams says.

“To find moulting shoveler in such an urban environment is completely without precedent — anywhere.”

Writing to Mayor Garry Moore, Dr Williams says the ponds were a surprise. “I wasn’t prepared for the astonishing wildlife spectacle the oxidation Bromley ponds presented. Without doubt, you have under your management a profoundly important wildlife habitat.”

The designers who built the ponds with heavily planted islands were people of great foresight, he says. “I suspect wastewater treatment plants like this become especially important to waterfowl during years when El Nino droughts hit our eastern landscapes,” Dr Williams writes. “At these times... the availability of the ponds and nearby feeding resources in the estuary and on adjacent farmland may be the difference between life and death for many waterfowl.