Hawaii National Park, Hawai‘i – It’s a precarious time of year for one of Hawai‘i’s rarest endemic seabird species, and the national park is keeping a watchful eye on its small population.
The ‘ua‘u, or Hawaiian petrel (Pterodroma sandwichensis), is a federally endangered native seabird, and the only known nests on Hawai‘i Island are within Hawai‘i Volcanoes National Park on the lower alpine and subalpine slopes of Mauna Loa. Wildlife biologists estimate that only 50 to 60 breeding pairs are left here.
Hawai‘i Volcanoes National Park was designated a World Heritage Site due in part to the high number of endemic species, like the Hawaiian petrel, it protects. This year the park celebrates 25 years of World Heritage by offering a series of educational programs about the natural and cultural resources in the park.
In November, young ‘ua‘u leave their nests for the first time and fly at night to the ocean searching for food. A primary threat to fledglings are bright urban lights that cause them to become disoriented and fall to the ground or collide with structures. Once grounded, it is difficult for ‘ua‘u to take flight, leaving them extremely vulnerable to cats, dogs and mongooses.
While a primary threat on other islands, groundings are not as common on Hawai‘i Island, likely due to a much smaller population of ‘ua‘u combined with minimal urban lighting, particularly in and around the national park. The last grounding in the park was in 2006. As a result, the park modified existing lighting to be downcast and shielded on the top, and the park pays careful attention to all new lighting to ensure it meets requirements to minimize disorientation.
Adult ‘ua‘u arrive on land in early spring and nest in underground burrows, entering and leaving after dark. The female lays a single egg in May. Both parents take turns incubating for 60 days and then feed the chick until it fledges in November or early December.
‘Ua‘u are 16 inches from head to tail, have a three-foot wingspan, and are dark grey on top and white below. They make a variety of calls and one sounds just like its name: oo-AH-oo. Photo credit: Courtesy of Jim Denny.