Nesofregetta fuliginosa
Polynesian storm petrel
(Also: Polynesian storm-petrel)

Polynesian storm petrels are found throughout much of the tropical Pacific, from Vanuatu in the west to Sala y Gomez in the east. Not much is known about their distribution and behavior outside of the breeding season, but they are thought to remain near their breeding islands, possibly concentrating in the region of the equatorial current (between 10 degrees north and south). (Brooke, 2004)

Polynesian storm petrels are found in tropical oceanic waters and on small coral or volcanic islands where they breed. They dig burrows on nesting islands, either among vegetation or in rock crevices. They may forage mainly in the waters near islands where they breed, but little is known of their habits. Other sources suggest they are mainly pelagic, except when breeding. (Brooke, 2004; del Hoyo, et al., 1992)

Polynesian storm petrels are about 24 to 26 cm in length and exhibit a wide range of color variation. Color morphs range from light to dark and the frequency of morphs varies geographically. Some populations have only light morphs, some only dark, and some have various morphs. They are large petrels, with broad, rounded wings and forked tails. The wings do not have marked curvature of the leading or trailing edges, which is distinctive in this species. The most common plumage pattern is with a brown to black dorsal parts, from the head to the tail, with a white rump band and bar dorsally across the wings. The throat is white, with a brown chest band and the breast and belly are white. The darkest morphs are uniformly sooty-brown, being similar in appearance to Tristram's storm petrels (Oceanodroma tristrami) but larger. Intermediate morphs have light flecking on their dark plumage. Polynesian storm petrels have a distinctive way of taking flight: they kick off from the ocean, glide for about 30 seconds, and then kick off again before finally lifting off. Wings are from 175 to 219 mm, bills are from 14.5 to 19 mm, the tail is from 83 to 122.5 mm, and mass is from 56 to 86 g. They have narrow webs on their feet. There are no described subspecies and no sexual dimorphism is reported, although geographic and sexual variation in body measurements is possible. (Brooke, 2004; del Hoyo, et al., 1992)

Little is known about mating in Polynesian storm petrels. (Brooke, 2004)

Little is known about breeding in Polynesian storm petrels. They nest in colonies on islands throughout their range. Nests are in burrows under vegetation or in rocky crevices. Nests are occasionally burrowed into sandy soil, but these are fragile and prone to collapse. Egg-laying seems to occur throughout the year, with some concentration of egg-laying from August to December on Kiritimati and July to September in the Marquesas. On islands closer to the equator, breeding seems to occur throughout the year, but on islands further south, breeding may be seasonal. Females lay a single egg. Time to incubation is estimated at about 50 days and time to fledging at about 60 days. (Brooke, 2004)

Polynesian storm petrel males and females both protect and feed their young to independence. However, little is known of the details of parental investment. Young are protected in nest burrows until they fledge. (del Hoyo, et al., 1992)

Lifespan in Polynesian storm petrels is not known.

Little is known about the life history of Polynesian storm petrels. They breed in colonial nesting colonies on coral or volcanic islands. Most individuals arrive at breeding colonies at night but some arrive during the day as well. This indicates that they may forage mainly during the day and return to burrows at night to rest. They are thought to be sedentary, mainly staying in the area of their breeding colony, but little is known of their movements. (Brooke, 2004)

Home range sizes in Polynesian storm petrels are not known.

Polynesian storm petrels produce soft "grr" calls, but the context of these calls has not been well-documented. (Brooke, 2004)

Little is known about the diet of Polynesian storm petrels. Like other storm petrels, they probably eat a variety of fish, cephalopods, and crustaceans. They forage mainly while in flight, grabbing prey from the surface or making brief, shallow dives. (Brooke, 2004; del Hoyo, et al., 1992)

Polynesian storm petrels have been extensively preyed on at breeding colonies by non-native mammalian predators, including domestic cats (Felis catus), ship rats (g.Rattus rattus), and house mice (Mus musculus), all of which take eggs, hatchlings, and fledglings. Native predators have not been reported, but are likely to include gulls and skuas. Polynesian storm petrels seem to visit breeding colonies mainly at night, indicating that they try to avoid avian predators by minimizing their exposure. (BirdLife International, 2009; Brooke, 2004)

Polynesian storm petrels are predators of fish, cephalopods, and crustaceans in the areas they live. Otherwise, almost nothing is known of their ecosystem role. They are rare, so their impacts are probably small at the ecosystem level throughout most of their range.

Polynesian storm petrels are important, although rare, members of native, tropical Pacific environments. They may attract ecotourism interest.

There are no adverse effects of Polynesian storm petrels on humans. (Brooke, 2004)

Polynesian storm petrels are considered vulnerable by the IUCN because of the local extinction of many breeding populations throughout their range in the last 50 years. These localized extinctions are primarily the result of decimation by introduced predators on their breeding islands. However, surveys have not been comprehensive and healthy breeding populations may still exist. Populations are estimated at a maximum of 10,000 individuals, but may be smaller. Polynesian storm petrel populations have become extinct in the Cook Islands, Tahiti, Henderson Island, and possibly Fiji. Breeding populations number only in the 10's in New Caledonia, the smaller Society Islands, Samoa, and the Australs and Marquesas Islands. Larger populations are supported on the Line Islands, Phoenix Islands, Gambiers Islands, and Sala y Gomez. Cat and rat eradication programs on some islands have had mixed success and are considered essential to the long-term survival of this species. Reintroduction efforts at Jarvis Island National Wildlife Refuge (near Kiritimati) have had limited success. (BirdLife International, 2009; Brooke, 2004)

Nesofregetta fuliginosa is also known by the common names white-throated storm petrels and Samoan storm petrels. This species was previously recognized as Procellaria fuliginosa. (Brooke, 2004; del Hoyo, et al., 1992)