Prion surprise on West Coast offshore island
Conservationists have been stunned to discover the West Coast's largest seabird colony while exploring a tiny island near Westport.
West Coast Blue Penguin Trust members were recently searching for sooty shearwaters on Wall Island, about 120m offshore from Cape Foulwind, but were astonished to discover about 4500 fairy prions and about 300 shearwaters had made the rocky outcrop their home.
They were also amazed the island appeared predator-free, which meant the birds had a safe place to breed.
Trust chairwomen Kerry-Jayne Wilson, a seabird expert, said it was exciting to find so many fairy prions, which no longer nested on the mainland because of predators.
The entire island was riddled with burrows and the group had to step very carefully to avoid falling through them.
"We would be one of very few people to ever step foot on the island above the shoreline," Wilson said.
It was rare in New Zealand to find an inshore island so close to the mainland that remained predator free, she said. "Virtually every bit of rock around New Zealand which doesn't have mammal predators has seabirds and virtually every piece of rock that does have rats, stoats, cats and dogs doesn't have seabirds."
The trust's find was significant news to the Department of Conservation, which had been unsure of bird numbers on Wall Island.
"Even though the birds are reasonably common, the habitat they create is gone from the mainland and seabird colonies on inshore islands are the last remnants of how New Zealand used to be," DoC scientist Don Neale said.
The trust planned to set up traps on the adjacent mainland to ensure the island remained predator-free.
Fairy prions, the smallest prions and part of the petrel family, only used the island during summer to breed. Sooty shearwaters, also called muttonbirds or titi, are almost extinct on the mainland.
Black-backed gulls, white- fronted terns, red-billed gulls and probably blue penguins also nest on the island.