Waikato University researcher aims to make kokako feel home away from home

We all get a warm fuzzy feeling when we hear a familiar accent in a strange place – it can make you feel like you’re home away from home.

There is evidence that birds respond in a very similar way, and in a project starting this month researchers at the University of Waikato will use birdsong ‘dialects’ to help re-establish native kokako populations in two North Island forest locations.

Currently there are only a few hundred kokako pairs still left in the North Island, while the species has been declared officially extinct in the South Island. Conservationists hope to expand the population by relocating birds to old-growth native forest areas where the mammals that could prey on kokako have been eradicated.

To make them feel they’re among friends, the newly released birds will be exposed to kokako songs recorded in their original habitats and played over loudspeakers in their new homes.

“It’s well known that birds know their neighbours and can distinguish strangers,” explains PhD student David Bradley, who’s previously studied birdsong in Costa Rica.

“The idea is that the birds being released should be familiar with these songs as they’ve been recorded very close to where they came from. So that encourages them to hang around instead of fleeing.”

Acoustic anchoring, as it’s known, has been used with some success twice before with these endangered native birds, but little is known about the function of birdsong dialect. What happens, for instance, when birds from different areas and dialects are combined into a single population?

Mr Bradley is hoping the Marsden-funded kokako project, a collaboration between the University of Waikato, DoC and Ark in the Park, will shed some light on the matter.

Each location will receive birds from two different ‘dialect groups’. Twenty kokako from the Urewera National Park will be relocated to the Whirinaki Forest Park near Murupara, and another 10 birds each from native forests east of Te Kuiti and east of Te Awamutu will be rehomed in the Waitakere Ranges.

“Birds often share aspects of songs with their neighbours,” explains Mr Bradley.

“If you listen to kokako singing, they echo phrases. By introducing kokako from two ‘dialect groups’ into each location, we want to find out how the birds respond to the different dialects we’ll be playing every dawn through loudspeakers, and whether the birds which share a dialect will cluster together.”

The rehomed birds will be fitted with tiny radio transmitters so the researchers can track their location.

“We expect at first they’ll disperse quite a bit,” says Mr Bradley.

“It’s a natural reaction to being captured. But they’ll have heard the first burst of song while they’re still in the aviary before being released, so hopefully they’ll come back again.”

Mr Bradley – who came to NZ from Canada – had never seen or heard the kokako until this year (“I had to look on the internet,” he admits). He says doing his PhD at Waikato makes sense because NZ is a world leader in bird translocation.

“You’re way ahead of the game, mainly because the conservation problems in NZ are so severe. Islands often suffer these sorts of problems.”