Cats suspected in sea-bird kill on Maui
By Timothy Hurley
Advertiser Maui County Bureau
HO'OKIPA, Maui — A rare colony of wedge-tailed shearwaters, a native Hawaiian sea bird, was nearly wiped out by one or more feral cats in attacks over the last two weeks, a state wildlife official said yesterday.
"This is a terrible biological loss,'' said state wildlife biologist Fern Duvall.
In all 96 adult birds were killed and 22 eggs destroyed.
The bite marks on the breasts and heads of the dead birds match the bite of a cat. The carcasses were left intact, indicating that the kills were not for food.
During an inspection of the site near Ho'okipa Beach Park yesterday, Duvall found only 15 of the colony's 73 burrows still active. But the number of deaths likely will rise, he said, because two shearwater parents are required to raise a chick.
While the wedge-tailed shearwater, or 'ua'u kani, is abundant in the Northwestern Hawaiian Islands, most of the birds around the main islands inhabit offshore islets where they are not threatened by cats and other predators.
The Ho'okipa colony is one of eight Maui communities of the brown-and-gray sea bird that is about the size of a pigeon. Scientists have been banding younger shearwaters at the former dump site near Ho'okipa Beach Park for three years.
Judging from the decomposed condition of the bird carcasses, Duval said that the carnage apparently began two weeks ago, with most of the kills occurring in the last five days.
Duvall said the Ho'okipa colony has been hit by cat kills before and he suspects that one or more animals from a cat colony maintained at or near the beach park is responsible for the damage.
But Aimee Anderson, animal control supervisor with the Maui Humane Society, said there is no record of a cat colony in the Ho'okipa area. While that doesn't rule out the possibility that someone is feeding cats in the area, animal control officers who patrol the park twice a week for leash-law violations haven't seen any cats, she said.
Anderson said the Maui Humane Society would be willing to help the state trap any cats that have been killing birds there.
"We're not going to put cats above the native species,'' she said.
While the Ho'okipa colony is virtually decimated for now, there is hope that it will recover in the years to come. Duvall said fledglings leave the nest for four years and don't come back until they are sexually mature. None of the banded birds were killed in the attacks, he said.
The threat of attack from wild cats is a constant one for sea birds in the main Hawaiian islands and especially for the wedge-tailed shearwater, which is awkward on the ground and unaccustomed to dealing with predators.
A study of Maui wedge-tailed shearwaters in 1999 and 2000 found that 65 percent of nested burrows failed to yield new birds, largely because of feline predation, Duvall said. By comparison, only 17 percent of the burrows at Molokini islet, which is free of cats, failed, and that was because of predation by native frigate birds.
Hawai'i's wedge-tailed shearwaters arrive on land in March. The pairs dig a burrow, and the female lays a single egg in June. Usually arriving at the nest at dusk and leaving again at dawn, the parents take turns feeding the burrowed chick.
