New Zealand muttonbirds that over-winter off the coast of Japan are being checked for radiation exposure from the damaged Fukushima nuclear power plant.
Scientists from the University of Auckland will investigate whether radioactive cesium has entered the New Zealand ecosystem or food chain via the birds.
The birds' feathers, collected from muttonbird sites in the South Island, will be tested for gamma rays that indicate radioactive isotope cesium-134.
The research is part of a wider look at effects of radiation from the Fukushima plant, which was severely damaged during Japan's 2011 earthquake and tsunamis.
Tens of thousands of people have been unable to return home to areas contaminated by radiation.
New Zealand muttonbirds, also known as sooty shearwaters or titi, migrate annually; mating and raising chicks during summer in New Zealand, spending winter off the coast of Japan.
Dr David Krofcheck of the University of Auckland's Department of Physics said the project aimed to determine the degree to which the mutton bird population was exposed to radiation.
"There is no evidence to indicate that the birds have been vectors of radioactivity so this research is very much about taking a precautionary approach," Krofcheck said.
"But detection of gamma rays would tell us whether the birds spend sufficient time near Fukushima to accumulate cesium-134 from nuclear fission.
Obviously the issue would then become whether that radioactivity is being absorbed into local ecosystems or the food chain."
Experts have said the Fukushima disaster was responsible for the largest single release of radioactivity into the ocean, threatening wildlife in the region.
Muttonbirds are a medium-large seabird. They are of cultural and economic value to Maori, who harvest the nearly fledged chicks during the annual muttonbird season.
The season runs from April to May and is restricted to Maori and their whanau who use the birds for food, oil and feather down.
Krofcheck said consultation with Maori, the Rakiura Titi Islands Administering Body, about the research will begin as soon as possible.
The Ministry of Agriculture and Forestry said it had no information to suggest mutton birds might be significantly exposed to radioactive contamination, but it continued to monitor any new information that might cause it to change its advice to people about eating muttonbirds.
The research is being done in collaboration with the Department of Zoology, University of Otago, with funding from Lottery Health Research.
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