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Clarence River black fronted terns

A five-year programme to trap predators of black-fronted terns started at three breeding colonies beside the upper Clarence River in 2015.

Black-fronted tern on the Clarence River

Black-fronted tern on the Clarence River

Department of Conservation (DOC) ranger Mike Aviss said a survey counted 303 black-fronted tern-tarapiroe nests at the colonies last spring. Hedgehogs, ferrets and ship rats, wild cats and a stoat were filmed raiding 63 nests and eating eggs. In the last breeding season, 154 pairs of black-fronted terns fledged only 18 chicks. 

The colonies are on conservation land neighbouring Molesworth Station, between Jacks Pass and the Acheron River mouth.

Mr Aviss, a senior ranger based in Marlborough, said multiple agencies and landowners were pooling knowledge and experience to protect these endangered birds. The Canterbury Water Management Strategy Kaikoura Zone Committee would invest $90,000 over five years, Environment Canterbury $184,000 through its Canterbury Braided River Initiative and DOC $240,500.

“The programme will also involve clearing broom and willows from islands where terns like to breed,” Mr Aviss said. “This means there are fewer places for predators to live, hide and hunt.”

DOC ecologist Richard Maloney said the trapping and weed control should see more chicks growing to fledglings and surviving to breed. “If nothing is done, black-fronted tern populations are expected to decline a further 90 per cent in 25 years,” Dr Maloney said.

Kaikoura Zone Committee chairman Ted Howard said trapping predators was “part of a bigger programme of weed control along the Clarence River ‘ki uta ki tai’ – from the mouth of the river to the top of its 3500-square-kilometre catchment”.

In April about 1400 broom gall mite-infested twigs were dropped by helicopter into dense broom at the back of Cloudy Range and Hossack stations.  Another release would be made over conservation land in October-November, covering an area from Clarence Reserve to St James Station.

Scattered patches of broom, gorse, hawthorn and willow on public and private land were being sprayed from a helicopter, from St James homestead to Lake Tennyson.

John Murray, Clarence farmer and Kaikoura Zone Committee member, said landowners on Bluff Station, The Muzzle, Cloudy Range and smaller properties along the Clarence had paid for spraying on their land close to the riverbed.

“They saw the opportunity to get really good value for their weed control dollar and are keen to do their bit,” Mr Murray said.

Funding for this weed control came from the Zone Committee’s Immediate Steps budget, aimed at delivering Canterbury Water Management Strategy biodiversity goals. “The strategy is not just about cleaning up water that has become polluted but also about protecting an unspoilt river, lightly stocked with a single dwelling along its length,” John Murray said.

Counting the cost

Clarence River

Clarence River

Helicopter control of broom, gorse and hawthorn from the mouth of the Clarence to conservation land on Clarence Reserve – started spring 2014 and completed December: Kaikoura Zone Committee $70,000, DOC $10,000, landowners $10,000, Land Information New Zealand (LINZ) $25,000

    • Biological control of broom on private and conservation land, Clarence Reserve to St James Station homestead, in autumn and spring this year – Kaikoura Zone Committee $6000, $1500 each from Marlborough District Council, DOC and LINZ 
  • Five-year black-fronted tern predator control in the upper Clarence – Kaikoura Zone Committee $90,000, Environment Canterbury Braided River Regional Initiatives $184,500, DOC $240,500
  • Targeted spraying of scattered patches of broom, gorse and willow from St James Homestead to Lake Tennyson, started January 2015 – Kaikoura Zone Committee $12,000, DOC $6000

More information

Angus McLeod, Senior Communications Advisor, Environment Canterbury, 0275 497 691


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