If you travel to Hawaii’s Big Island, you are welcome to visit Mauna Loa, the largest volcano in the world; cats, however, are not— a point now being enforced by a new 5-mile-long fence constructed for the sole purpose of keeping felines away.
Mauna Loa’s lava-covered slopes make for some seriously forbidding landscape, but that hasn’t deterred cats, which have adapted to the Hawaiian Islands just fine since arriving on explorers’ ships. The little invasive predators are now a mortal threat to the endangered Hawaiian petrel, a seabird that breeds on Mauna Loa. Several thousand of the birds live in Hawaii, but only about 75 breeding pairs are in Hawaii Volcanoes National Park.
To protect the petrels, the National Park Service and other organizations spent nearly four years building the cat-proof barrier, a 6-foot-tall fence topped with a curved section that even the wiliest kitty is not supposed to be able to scale. It’s the longest anti-cat fence in the United States, and it encloses 600 acres of 8,000 to 10,000 foot-high terrain that petrels, also known as ‘u’au, now view as choice breeding territory.