24 November 2004

“Whio five” a first for Auckland Zoo

Auckland Zoo has, for the first time, successfully bred five of the nationally endangered torrent duck species, the whio (blue duck).

Born in two clutches over the past five weeks to breeding pair Peki and Kopakopa, the five ducklings represent valuable additions to the Department of Conservation’s (DOC) Blue Duck Recovery Programme.

DOC has recently reclassified the whio’s status from threatened to “nationally endangered”. It estimates that this species, the only torrent duck of its kind in the world, to be as low as 2,500 nationally, and declining. Contributing factors to their decline have been loss of suitable riverine habitats due to the clearance of vegetation from stream and river backs, water diversions, poor quality water, and damming for hydro and irrigation schemes. Introduced predators, particularly stoats, but also possums, cats and dogs, have also had an adverse impact.

Auckland Zoo has held whio at the zoo at various times since 1996, but this is the first time the species has been successfully bred.

Eggs were pulled from the nest at 20 days to increase the chances of a positive outcome, then artificially incubated in a temperature and humidity controlled environment, and weighed regularly to check their development. “One of the biggest challenges we faced with the ducklings was getting them on to artificial food in their first week,” says Native Fauna keeper Todd Jenkinson.

“We teamed the first two up with a Mallard duckling as a teacher duckling to show them what to do, and the latest three are with two native grey teal ducklings, and it’s worked extremely well. The older ones are now in an outdoor aviary, and the younger ones are putting on weight”.

The five whio will remain at the zoo’s Native Fauna Conservation Centre before being transferred to Peacock Springs in Christchurch for socialisation with other whio. They’ll also be fitted with radio transmitters. In early 2005, the ducks will then be released into a fast-flowing river habitat in the Mt Taranaki region. While these five will not be on public display, a male whio can be seen in the zoo’s NZ Native Aviary. You can also spot this endangered bird on the New Zealand $10 bill.

Mt Taranaki has been selected as an area to build up whio numbers, as there is already a natural population there, as well as enough habitat for more whio. A DOC pest control programme is carried out in the area and monitored closely.

“For the zoo and the programme to be successful, it’s not only important to breed whio, but also that the ducks survive in their natural environment,” says Mr Jenkinson.

The whio female is particularly at risk, as she is very vulnerable to predators when she is sitting on the eggs during incubation, a 32-35 day period.

Whio (Hymenolanimus malacorhynchos): a nationally endangered species of waterfowl endemic to New Zealand. It is the only member of its genus and has no close relative anywhere in the world. The whio is believed to have appeared at a very early stage in evolutionary history, and the species’ isolation in New Zealand has resulted in it acquiring a number of unique anatomical and behaviourial features.

Distinguishing features: streamlined head and large webbed feet to enable it to feed in fast moving water. The whio’s upper bill has a thick semicircular, fleshy ‘lip’, which overlaps the lower bill. This allows the duck to scrape off insect larvae that cling to rocks, without wear and tear.

It is one of only three species amongst the world’s other 159 waterfowl that live year-round on fast flowing rivers (the others are found in South America and New Guinea). The male makes a distinctive high-pitched aspirate sound – “whio”, in contrast to the female’s guttural, rattle-like call. Whio vigorously defend their river territories year-round. The size of each pair’s territory can vary (average is approximately 1.5 km) depending on the quality of the habitat and food available.

ENDS

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