Audubon's Shearwater

The Audubon's shearwater, Puffinus lherminieri, is a diminutive member of the petrel family, often referred to as the dusky-backed shearwater. This species, named in honor of the French naturalist Félix Louis L'Herminier, is a common tropical seabird with a length averaging 30 cm (12 inches) and a weight of 170 g. It exhibits a blackish-brown upperparts and white underparts, with a wingspan stretching between 64 to 72 centimeters.

Identification Tips

Upon first glance, the Audubon's shearwater may be easily mistaken for its relatives due to its small size and contrasting plumage of black above and white below. The head below eye level is white, and the iris is dark. Its feet are a dull pink with a black wash and black toenails, while the bill is grey with a darker tip and a hint of pink. Males and females are similar in appearance, and immature birds do not possess a distinct plumage.

Habitat

This species is highly adaptable, inhabiting pelagic, offshore, and inshore waters. It is not particular about its marine environment, thriving in a variety of aquatic habitats.

Distribution

The Audubon's shearwater has a widespread range, found across the Indian Ocean to the Arabian Sea, throughout the north-west and central Pacific, in the Caribbean, and parts of the eastern Atlantic. It is a bird of tropical waters, with some Atlantic populations and Bannerman's shearwater of the Ogasawara Islands venturing farther north.

Behaviour

Adult Audubon's shearwaters are not known for extensive wandering or migrations, though their young do so before breeding. They feed using various methods, including diving from flight, plunging underwater, and picking up food while "pattering" across the waves. Their diet consists of small fish, squid, and planktonic crustaceans. They are not typically ship-followers but may approach small fishing boats or join mixed-species feeding flocks.

Song & Calls

The vocalizations of the Audubon's shearwater, described as twittering calls and mewing, are most often heard at night within their breeding colonies.

Breeding

Audubon's shearwaters are colonial nesters, utilizing burrows and crevices on atolls and rocky islets. The breeding season varies by location and subspecies. Both parents share incubation duties for the single white egg, which hatches after 49–51 days. Nestlings are brooded for up to a week before being left alone in the burrow, with parents foraging to feed their offspring until they fledge at 62–75 days old. These birds reach breeding maturity around 8 years of age and are known for their longevity.

Similar Species

The Manx shearwater (P. puffinus) is similar in appearance but can be distinguished by its white undertail coverts and longer bill. The little shearwater (P. assimilis) may also be confused with the Audubon's shearwater but has more white on the face and underwing, a smaller bill, and greyish-blue feet.

Diet and Feeding

Audubon's shearwaters consume a diet of small fish, squid, and planktonic crustaceans, foraging by diving from flight, plunging from a swimming position, or picking up food while "pattering" across the water's surface.

Conservation status

While some small populations of Audubon's shearwaters are threatened, the species as a whole is not considered globally threatened and is listed as Least Concern on the IUCN Red List.