A five-mile-long fence was recently completed in Hawai'i Volcanoes National Park to protect the federally endangered Hawaiian petrel from feral cats. It’s the longest cat-proof fence constructed in the U.S.

The petrel, or ‘ua‘u in Hawaiian, nests deep in lava rock burrows on the slopes of the Mauna Loa volcano in the park, with nests found up to 10,000 feet high. Even at that altitude, feral cats prey on the petrels and their chicks, waiting outside the burrows or even reaching in to snatch a bird.

The fence protects the approximately 50 breeding pairs left in the park. About 15,000 of the seabirds live in colonies throughout the Hawaiian Islands.

Conservation fencing, or predator protection-fencing, was pioneered in New Zealand and Australia, two