First U.S. Predator-Proof Fence Delivers on Promises – Important Seabird Species in Hawaii Producing Chicks in Record Numbers

Contact: Robert Johns, 202-234-7181 ext.210,

Wedge-tailed Shearwater by George Wallace
Wedge-tailed Shearwater by George Wallace

(Washington, D.C., December 9, 2011) The first predator proof fence in the United States is producing dramatic results that may eventually lead to a resurgence in decimated seabird populations in Hawai’i. The Wedge-tailed Shearwater, which nests in the remote coastal dunes on the now-fenced Kaʻena Point at the northwestern tip of O’ahu, has produced the highest number of chicks since the annual survey began in 1994.

“This is extraordinary news. It has been only eight months since the predator-proof fence was installed and already, we are seeing results. This year’s chick count of 1775 is a 14% percent increase over the previous high count in 2007 and the highest number ever recorded at the point. So far, the fence has done a great job of preventing bird predation by rats, cats, mongoose, dogs, and even mice,” said Dr. George Wallace, Vice President for Oceans and Islands at American Bird Conservancy (ABC), the leading bird conservation group in the United States.

The project has been a cooperative effort involving Hawai’i’s Department of Land and Natural Resources (DLNR), the U.S. Fish and Wildlife Service, the Hawai’i chapter of The Wildlife Society, and local communities.

“We are very excited to be moving into the next phase of the project now that the native species are able to exist without predation pressure and we can begin active restoration of the native species. We hope this is the first of many projects like this in Hawai’i” said Lindsay Young, the project coordinator with Pacific Rim Conservation.

Ground-nesting seabirds in the area, which also include the Laysan Albatross, have been targets of predation by introduced mammals, with the result that up to 15% of chicks are killed each year. The predators have especially preyed on the young birds before they can fly, but they also eat seabird eggs and even attack adult birds. Despite intensive efforts to control these predators, they still pose a major threat to the survival of native species. The full moons in October and November often bring particularly devastating attacks on the Wedge-tailed Shearwater chicks as they leave their burrows for the first time at night and become vulnerable to predators roaming the area.

The marine grade, 2,040-foot long, 6.5-foot-high, stainless steel fence was installed to create a 59-acre area exclosure at Ka’ena Point Natural Area Reserve. The fence is the first of its kind in the United States, having been used successfully in 30 New Zealand coastal and forest projects, and tested on lava flows on the Big Island. The fence provides a combination of features including a rolled hood at the top, fine mesh between the fence posts, and a skirt buried underground, designed to prevent animals from jumping or climbing over, squeezing through, or digging their way under the fence and into the protected area.

The fence path largely follows a World War II-era roadbed that skirts along the bottom of a hill behind the point, above the sand dunes. By following this track at the base of the slope, the fence encloses the greatest area while minimizing interference with scenic vistas and avoiding further disturbance to the delicate habitat. To reduce visual impact, the fence was painted green to blend into the natural surroundings.

Access to the area for people was not changed due to this fence. People continue to visit Ka’ena Point Natural Area Reserve for fishing, hiking, bicycling, and other recreational and educational activities, entering through unlocked gates. To minimize the opportunity for predator incursion, a double-door system was employed where both doors cannot be open at the same time. Instead, a person accessing the Reserve must wait for the first door to close before the second door may be opened. The doorway area will be large enough to fit up to nine people or one person with a bicycle or fishing pole.

In addition to the shearwaters, native plants such as the endangered ’ohai and other coastal strand vegetation are benefiting from removal of rats and mice which eat flowers, seed pods, and seedlings. Native species are being monitored to document the effects that the removal of predators will have.

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