Whistle on the water
The whio duck is down to the last 3000 individuals, and it’s our job to protect them.
The whio has always been an iconic bird for the anglers, trampers, white water rafters and kayakers of Aotearoa. But those less familiar with the pristine waterways of our conservation estate may know only the blue duck, in all its azure glory, as the less famous bird on our ten-dollar note.
Once whio were found all over the country. But a lethal cocktail of egg-munching stoats, relentless forest clearance, water quality decline and general human ineptness has decimated populations, leaving less than 3000 individuals. Unfortunately, the whio’s preference for highcountry rivers means we can’t just whisk them off to pest-free, offshore islands to reproduce in undisturbed bliss.
In Fiordland, DOC has caught more than 400 stoats since December. Te Anau Biodiversity Ranger Andrew Smart says that in areas lacking stoat control, eggs, and some unlucky mother ducks, were eaten after only nine days on the nest (out of 35). Because female adults are more likely to be caught, it’s hard for populations to recover. Not a single duckling made it to the river when stoats weren’t controlled, compared with nine the year that stoat trapping was implemented.
Research has led to stoat trapping in eight ‘security sites’, high priority areas for whio conservation. The goal is to conserve 400 breeding pairs – 50 at each spot – by 2016.
Whio Operation Nest Egg is another ingenious attempt to ramp up numbers. Eggs are pinched from unwary whio who re-nest, whilst collected eggs are incubated, reared and then re-released, effectively doubling numbers. Blue duck usually mate for life, but there are the odd unscrupulous whio to be found. “We’ve had birds that divorce quite regularly. We’ve got a male who we call ‘Hugh’ after Hugh Heffner, and he gets a new, younger partner nearly every year,” says Smart. Whio live for an average of 10 years in the wild.
Whio are highly specialised birds, with adaptations for a life in rapidfilled rivers. Their giant, webbed feet can fold back into ‘grooves’ in their legs to make them more streamlined, whilst their blue-grey colour camouflages them amongst river boulders. Whio are unique to New Zealand.
Whio rely on aquatic insects such as stoneflies which thrive in good water quality, and are therefore an ideal indicator of a river’s health, says Robert Hood, Programme Manager at Ruapehu. They have a rubbery vacuum cleaner on the end of their bill, used for hoovering up insects and larvae which live under the rocks, which they sieve out into their mouth.
Hood admires the whio’s ability to thrive in “a very tough environment”. Born into dangerous surroundings, ducklings are very vulnerable to predation, flood events and being swept downstream. Luckily, adult whio are diligent and observant parents.
Whio are more endangered than the kiwi, so Whio Awareness Month is a good excuse to don your tramping boots and head riverside to catch a glimpse of these curious ducks in their natural habitat.
“We’ve got a male who we call ‘Hugh’ after Hugh Heffner, and he gets a new, younger partner nearly every year”
DOC Te Anau Biodiversity Ranger Andrew Smart
Photos: Alan Gibson