HAWAIIAN PETREL } Pterodroma sandwichensis
DESCRIPTION: The Hawaiian petrel is a large, dark grey-brown and white petrel, measuring 16 inches in length with a wing span of three feet. The bird has a dark-gray head, wings, and tail, and a white forehead and belly. It has a stout, grayish-black bill that is hooked at the tip, and pink and black feet. The petrel has a distinctive call during breeding season that sounds like “oo ah oo.” It also has calls that sound like the yapping of a small dog.
HABITAT: When not at sea during the breeding season, the species nests in burrows, primarily in remote montane locations, along large rock outcrops, under cinder cones, under old lichen-covered lava, or in soil beneath dense vegetation. These birds can nest in a variety of environments, from rainforest to subalpine rocky cliffs, and will breed successfully as long as they are protected from predators.
RANGE: This fast-flying seabird ranges thousands of miles over the central tropical Pacific. Although historically the bird’s nesting grounds were distributed throughout the Hawaiian Islands, threatened nesting habitat has restricted them to a few remote high-elevation sites, including Haleakala crater on Maui, the West Maui Mountains, Mauna Kea on the island of Hawaii, Waimea Canyon on the island of Kauai, Lanaihale on Lanai, and possibly the island of Molokai.
MIGRATION: During the nonbreeding season, Hawaiian petrels range throughout the central Pacific.
BREEDING: The bird ‘s breeding season extends from March to October. It has a clutch size of one egg. The Hawaiian petrel returns to the same nest site year after year. It is believed that the species is monogamous and lives in pairs.
LIFE CYCLE: The incubation period for the Hawaiian petrel is 55 days. Chicks remain in the burrow for about four months after hatching and are visited briefly and fed by their parents throughout that period. They fledge at about 110 days and at that point are independent of their parents. Hawaiian petrel chicks spend the first several years of their lives at sea. They do not start breeding until they are about six years old, and they may not breed every year. Adult birds may live for 30 years or longer.
FEEDING: The Hawaiian petrel feeds primarily on squid but also eats fish, crustaceans, and plankton.
THREATS: A principal threat to this species is depredation of eggs and young by introduced feral predators, including cats, rats, dogs, pigs, and mongoose. In addition, the species is threatened by development; light pollution; collision with power lines; ocean pollution; and disturbance of their breeding grounds by goats, pigs, and cattle. Fledgling birds can become grounded when they become disoriented by lights on their nocturnal first flight from the inland breeding sites to the ocean. Once grounded, they are unable to fly and are killed by feral predators or die from starvation or dehydration.
POPULATION TREND: The population estimate for this species is 9,000 to 16,600 birds, with a decreasing trend.