The 'ua'u belongs to the expansive Procellariidae family, which encompasses over 50 species of petrels. These seabirds can be found across all of the world's oceans and nearly all of its seas.
Like its seafaring cousins, our Hawaiian petrel spends nearly all of its time on the open water. But between March and November, 'ua'u will return to the highest peaks on the Hawaiian islands, such as Haleakalā on Maui, in order to breed and raise their fledglings.
Despite its long mating season, catching sight of an 'ua'u on land is still a rare feat. These seabirds venture inland only at night, and their dark grey top feathers make them difficult to spot against the rockfaces where they construct their burrows. However, you may be able to hear their distinctive oo-ah-oo mating call, which earned the 'ua'u their name.
'Ua'u chicks used to be considered a great delicacy, reserved for the ali'i. Unfortunately, petrel fledgings are also a favored snack of many non-native predators, such as rats, mongooses, and particularly feral cats. This predation, along with habitat loss, has greatly reduced 'ua'u populations on the islands. They are currently listed on the International Union for Conservation of Nature Redlist as endangered, with an estimated 7,500 to 16,600 mature birds remaining.