Kokako given a fighting chance

Biodiversity senior ranger Brad Angus says controlling pests is key to the success of the kokako population.

A small population of endangered kokako in the Kaimai Mamaku Forest has the potential to become one of the largest in New Zealand.

Department of Conservation biodiversity ranger John Heaphy says the threatened species is part of a North Island recovery programme.

Kokako have come back from near extinction in the forest after a pest control project kicked off over a decade ago. "In 2000 we originally had 10 pairs with no successful breeding due to predation. Now it's up to 24 pairs and 24 single birds, so we have more than doubled the breeding population."

The figures might not sound a lot but reflected the challenge of restoring an ageing population, he says. "Often in remnant kokako populations there are a number of same-sex pairs so there was a strong likelihood we initially started with only a handful of very old females.

"It's harder when all the individuals are old and there are very few females because they've succumbed to predators while sitting on a nest incubating eggs. So any initial young ones that are produced are just replacing the ones that die of old age. It actually takes a long time to get the older age structure down to young and it's only now that we are starting to get significant increases in the total population and a better ratio between male and female."

That success could be attributed to eliminating pests before the kokako breeding season.

"The department has been running pest control in the spring since 2003 over 1000ha, dropping the pest numbers immediately prior to the breeding season so you get the best bang for your buck."

Biodiversity senior ranger Brad Angus says pests are trapped or killed with toxins laid at bait stations.

Heaphy says kokako populations are managed around the country and it is hoped nationally the number of breeding pairs will eventually reach 2000. "Once it gets to that stage then we can start to relax. And while this population is one of the smallest, it has the potential to become one of the biggest because of the large area of forest they can expand into."

Kokako facts

*The North Island kokako is found mainly in mature podocarp-hardwood forests.
*Fewer than 400 pairs occur in isolated groups in parts of the central and northern North Island.
*In the past 20 years, numbers of North Island kokako have declined significantly, although management is reversing that trend in many areas.
*Kokako are renowned for the clarity and volume of their song, which carries far across the forest.
*Male and female are similar in colour and size (weighing about 230g).
*They protect large territories (8ha) by singing and chasing away invaders.