Hutton’s shearwater colonies hit hard
The impact of November’s 7.8-magnitude earthquake on the endemic Hutton’s shearwater is worse than first thought.
Hutton’s Shearwater Charitable Trust chair Ted Howard said the earthquake on November 14 hit the birds extremely hard. Only 10 per cent of the chicks may have survived.
‘‘If the birds are to survive long term the trust urgently required more funding,’’ Howard said.
‘‘From early overflights and photos we estimate that more than 20 per cent of the Kowhai colony and 30 per cent of the Shearwater Stream colony have been swept away by slips.
‘‘As birds were sitting on eggs at the time, it’s likely that at least one of each nesting pair was taken to their deaths.
‘‘In slowly reproducing species like the Hutton’s shearwater, the loss of adult birds means a major impact on the population.’’
The seabird only breeds in the high mountains around Kaikoura and its numbers were already in steep decline. Hutton’s shearwater colonies have declined from 10 sites known in the early 1960s to two natural and one man-made colony today.
Earlier this month Department of Conservation Kaikoura ranger Mike Morrissey and Hutton’s trustee Nicky McArthur inspected 100 active burrows near the Kowhai research hut.
Howard said the burrows looked undamaged from the air, but of the 100 burrows, 36 were completely blocked, and only one live chick was observed.
Although numbers vary year to year somewhere between 200 to 1000 birds crash land in the Kaikoura township during March and April on their maiden flight to sea.
‘‘The fact that 22 crash-landed birds have been handed in indicates that some chicks have survived, but we suspect the survival [rate] this year will be well down on normal,’’ said Howard.
‘‘There is so much variation but we estimate only 10 per cent of the chicks will have survived.
‘‘In addition to low breeding success and far above average loss in adult numbers, the risk of being decimated by introduced mammals has increased following the earthquakes.’’
Vast amounts of gravel in the valley floors now make the area more accessible to predators, including pigs who feast on the birds, Howard said.
‘‘If these birds are to survive long term now more than ever before, they will need our help.
‘‘Helping these seabirds to survive is something that requires help from well beyond Kaikoura.’’
Only a few crashlanded birds have been handed in during March Fly Safe month, and the Hutton’s Shearwater Charitable Trust estimates that up to 10 per cent of chicks have been lost due to last year’s earthquake.