Once spread throughout the country, today this uniquely coloured bird is rare. Like the kiwi and kakapo, the whio’s survival is under threat.

Over the past 150 years, whio numbers and range have declined significantly. There are fewer whio in fewer places there ever before.

With funding provided under the New Zealand Biodiversity Strategy, researchers are now finding out more about the reasons for the whio’s decline. Already, the information gained is helping to target conservation efforts.

Key threats to survival
Habitat loss from forest clearance is one of major causes of the whio’s decline.

Whio is one of only four duck species worldwide to spend its entire life in a river habitat. Where forests have been cleared close to river edges, whio resting and nesting sites have disappeared. Declining water quality has also reduced the numbers of aquatic insects that provide the duck’s sole food.

Predation from introduced pests is another major factor in the blue duck’s decline. New research made possible with New Zealand Biodiversity Strategy funding has found stoats are a significant threat to the whio’s survival.

In 2001/2002, NZBS funding was provided to researchers studying the duck’s decline in Fiordland. The researchers found that stoats were the main cause of blue duck loss. Video footage shows stoats attacking females and stealing eggs from nests. Stoats will also take young ducklings from the river’s edge.

Reversing the whio’s decline
The results of the Fiordland study have provided valuable information to assist the Department of Conservation's whio recovery programme.

In 1997, the Department put in place a recovery plan to help ensure the survival of this unique New Zealand bird. The plan aims to protect key populations in six different regions of New Zealand and monitor the long-term trend of others. It also seeks to protect all rivers where blue duck live.

With mounting evidence of the impact of stoats on blue duck survival, predator control will be a focus of ongoing work to save the blue duck. More research will also be needed to help identify the factors critical to blue duck survival and reproduction.

Long term, the recovery plan's goal is to make sure whio survive in New Zealand's wild river habitats where they have lived for many millions of years.

In November 2002, the Department’s efforts to save whio received a welcome boost on the West Coast after a sponsorship offer from coal producer and distributor, Solid Energy New Zealand Ltd.

Solid Energy’s offer of $50,000 over three years will be used to fund an experimental stoat trapping and monitoring programme in the Kahurangi National Park near Karamea.