White weka a rare sight

It might look like a seagull fossicking in the undergrowth, but this photo shows a white weka captured on film deep in the Abel Tasman National Park.

The rare white bird was seen earlier this week by Department of Conservation ranger Fay McKenzie , who was back in the park beginning to check traplines again for the first time since lockdown.

The weka’s white feathers, orange bill and legs, and dark eyes are thought to stem from leucism, a condition similar to albinism where animals lack pigmentation. The condition causes pale, or patchy skin, hair, feathers or scales. It differs from albinism as it doesn’t affect an animal’s eyes, which are generally pink or red in albino individuals.

Biodiversity ranger John Henderson said in his 18 years working for the Department of Conservation, six of those in the Abel Tasman, he had never seen a white weka. A white bird had been seen by another ranger in the same area a few months ago and Henderson said it was likely to be the same one.

He said there were good numbers of weka right throughout the 22,500 hectare national park at the top of the South Island as a result of predator control work, but it was the first white weka on their records.

‘‘Anyone tramping down there should keep their eyes peeled for it.’’

A white coloured weka was also seen deep in the Kahurangi National Park in January 2018 outside Larrikin Creek Hut.

Project Janszoon ornithologist Ron Moorhouse said the genetic mutation that caused leucism was rare because both parents must carry the gene for it to develop. Spotting the weka was a ‘‘once in a lifetime’’ event.

‘‘You only see these kinds of things when a species or population is quite numerous because the chances of it happening are low, you need a lot of birds before you get these kinds of mutations coming together in the same individual.’’

Weka had all but disappeared from the Abel Tasman National Park in the 1980s and 90s. In 2006, the species was reintroduced at To¯taranui using birds captured in the Marlborough Sounds.

Moorhouse said the appearance of a white bird showed there were a lot of weka in the Abel Tasman and he estimated the population to be in the thousands.

‘‘Weka have made this incredible recovery in this area and nobody, including me, really knows why.’’

For a flightless bird that nested on the ground, Moorhouse said weka had made a fantastic comeback.

‘‘They are tough survivors.’’