Newell's Shearwater

The Newell's shearwater, or Hawaiian shearwater, known locally as ʻaʻo, is a relatively diminutive member of the Procellariidae family, measuring 33 centimeters in length. Its wingspan stretches between 223 and 249 millimeters, and its tail from 78.9 to 88.8 millimeters. This seabird tips the scales at a modest 0.340 to 0.425 kilograms. The plumage is a dark, blackish hue with a brownish tinge above, while its underparts gleam white. A distinctive white patch adorns the flanks, bleeding onto the rump's sides. The underwings are predominantly white, edged with darkness, and the undertail-coverts exhibit a black and white pattern, though they appear white when observed in the field. The bill is a somber grey or brown, and the legs and feet are chiefly a pale pink.

Identification Tips

In flight, the Newell's shearwater can be seen skimming the ocean's surface on stiff wings, alternating between short glides and bursts of rapid flapping. Its facial dark coloration dips below the eye, creating a stark contrast with the white throat. The bird is recognized by its braying call, reminiscent of a donkey, particularly near its breeding grounds.

Habitat

This shearwater favors the mountainous slopes of the Hawaiian Islands for nesting, often concealed by the uluhe ferns.

Distribution

The Newell's shearwater breeds across at least 20 colonies within the Hawaiian archipelago, predominantly on Kauaʻi but also on Molokaʻi and Hawaiʻi Island, with potential sites on Oʻahu, Maui, and Lānaʻi. From April to November, it is observed in Hawaiian waters, especially around Kauaʻi, and disperses into the tropical Pacific Ocean outside the breeding season.

Behaviour

The Newell's shearwater is a pelagic bird, feeding in deep waters and diving up to 10 meters to pursue squid and small fish. It is known to congregate with other seabirds, drawn to the commotion caused by schools of tuna.

Breeding

Once feared extinct, the Newell's shearwater was rediscovered in 1947 and found breeding on Kauaʻi in 1967. Nesting occurs in burrows on steep slopes, with a single white egg laid in early June. Both parents share incubation duties, which last approximately 62 days. The fledglings take to the sea in October, becoming independent shortly thereafter.

Conservation Status

The Newell's shearwater is currently classified as Critically Endangered. Its decline is attributed to habitat loss, predation by invasive species, and the hazards of urban lighting, which disorient young birds, leading to fatal collisions. The population, once estimated at 84,000 in the mid-1990s, has suffered a severe downturn, exacerbated by the aftermath of Hurricane Iniki in 1992.