Christmas Shearwater | Puffinus nativitatis

Voice

At sea the species is, like most shearwaters, essentially silent. At the breeding colony it is mainly nocturnal, calling from a rock crevice or dense vegetation; little has been published on the exact sound of this species, but it fits the hoarse, cackling and wailing repertoire typical of most relatives in the genus Puffinus.

Identification

An entirely dark shearwater, mostly blackish-brown with a rusty tinge, largely lacking the pale underwing pattern shown by many other shearwaters; only the chin and a narrow band beneath it are faintly paler. The bill is dark and clearly hooked, the legs pink. The head looks relatively bulbous and the tail short compared with similar species. No distinct juvenile plumage has been described; chicks are covered in dark grey down.

Confusion species

Sooty Shearwater is far larger and shows an obvious silvery flash under the wing that this species lacks. The dark morph of Wedge-tailed Shearwater, which breeds on the same Pacific islands, has a longer, wedge-shaped tapering tail and a paler bill. Bulwer's Petrel is much smaller and slimmer, with a long pointed tail, a pale diagonal band across the upperwing coverts, and a far more fluttering flight.

Habitat

At sea this is a truly oceanic species that forages far from land over deep, warm tropical water and depends heavily on predatory fish and dolphins driving small fish and squid to the surface. It breeds colonially on low, sparsely vegetated coral and sand islands, nesting in rock crevices, under shrubs, or in shallow burrows, less deeply dug than in most other members of the genus.

Range and movements

The species breeds on scattered islands of the central and eastern tropical Pacific; within the guide area that means the Northwestern Hawaiian Islands, with Laysan, Lisianski, Nihoa and Midway Atoll as the main colonies, together holding fewer than three thousand pairs. Eggs are laid there from February, and the last chicks do not fledge until October or November, after which the colonies largely empty out. Outside the breeding season the birds disperse widely across the tropical Pacific, with scattered, irregular records as far as the waters off Mexico and Guatemala.

• Breeding (summer)

Where and when to look

For ordinary observers this species is essentially inaccessible within the guide area: the breeding islands lie inside the protected Papahanaumokuakea Marine National Monument, which is closed to visitors, and for the rest of the year the bird disperses over open ocean far from any shipping lane. Only a research cruise inside the monument, or exceptional luck on a pelagic trip far northwest of the main Hawaiian Islands, could produce a sighting.

Conservation

The species is listed globally as Least Concern (LC), but the Hawaiian breeding population of fewer than three thousand pairs is vulnerable to introduced rats and feral cats, to habitat loss from introduced rabbits and plants, and on some islands to introduced ants that kill chicks.

Scientific name

Puffinus nativitatis | Streets, 1877

American naval surgeon and naturalist Thomas Hale Streets described the species in 1877 as Puffinus (Nectris) nativitatis, with Nectris used at the time as a subgenus of Puffinus; because the species has remained in the genus Puffinus, author and year stand without parentheses. The genus Puffinus was already introduced in 1760 by Brisson. The species name nativitatis is Latin for 'of the birth' and refers to Christmas Island (Kiritimati) in the central Pacific, where the first specimen was collected and which is also the type locality.