Central Hawke's Bay: Locals help to uncover secretive bittern world

By Nicki Harper

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Emma Williams and Kimi, the first dog in New Zealand trained to look for bittern, search out radio-tagged birds. Photo John Cheyne
Emma Williams and Kimi, the first dog in New Zealand trained to look for bittern, search out radio-tagged birds. Photo John Cheyne

A research project into the endangered Australasian bittern at Lake Whatuma near Waipukurau is gaining traction, with significant new information coming to light, and the community helping to protect the wetland-dwelling bird.

Known as matuku in Maori, this bittern is native to New Zealand, Australia and New Caledonia, and with the destruction of wetland habitats to make way for farm land and towns, its numbers have declined rapidly over the years.

It is now as much under threat as species such as the brown kiwi and blue duck, and ongoing habitat loss, coupled with predation and poor water quality, is putting further pressure on those that remain, estimated to be fewer than 1000 birds across the country.

The mottled, brown markings of the bittern make for perfect camouflage among the raupo. Photo / John Cheyne
The mottled, brown markings of the bittern make for perfect camouflage among the raupo. Photo / John Cheyne

Lake Whatuma is home to about 25 per cent of the total Hawke's Bay bittern population, and local surveys and research are uncovering previously unknown and nationally important information about how the birds live and behave.

For the last four years Massey University doctorate student Emma Williams has been finding and monitoring the bitterns at the lake as part of her research into cryptic species.

"Cryptic refers to them being secretive and camouflaged, and the bittern is the perfect case study."

Ms Williams' work is being aided and complemented by parallel investigations undertaken by Racecourse Rd residents John and Gail Cheyne, as well as efforts by the Hawke's Bay Ornithological Society, Department of Conservation, CHB Forest and Bird and the Hawke's Bay Regional Council.

"We live across from the lake," said Mr Cheyne. "One day we found there was a booming bittern - we started taking a kayak out to look for them ourselves.

"The work by Emma then became a catalyst for landowners and waterfowl hunters to do something about the threats and about three years ago we formed the Lake Whatuma Wetland Care Group."

One of the 10 birds at Lake Whatuma that have been fitted with radio transmitters. Each of the birds has been given a name - this one is  Bing Crosby. Photo / Emma Williams
One of the 10 birds at Lake Whatuma that have been fitted with radio transmitters. Each of the birds has been given a name - this one is Bing Crosby. Photo / Emma Williams

The 'booming' refers to the voice of the male bittern - a distinctive call assumed to be related to breeding.

So far, 12 male bittern have been found at the lake, but the numbers of females are still unknown.

The significance of this project at this site was that for the first time in the country a way to detect, capture and monitor the birds had been developed, said Ms Williams.

"The only time they had been caught in the past was in the 1980s with helicopters, but we have now found a new way and have managed to attach transmitters to 10 of the male birds."

The transmitters have recently led to the discovery that the birds leave Lake Whatuma during summer and autumn when the water level drops, heading to nearby farms, before returning in August to breed.

The landowners are now part of the research, providing information about where the birds are.

- Hawkes Bay Today

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