Ainley's Storm Petrel

The Ainley's storm petrel, Hydrobates cheimomnestes, presents itself as a medium-sized seabird, approximately 18 cm in length. Its plumage is predominantly a dark sooty-brown, which may appear black from afar, especially before the molt when the feathers are freshest. As the plumage wears, a more brownish hue may be discerned. A distinctive feature is the white rump, adorned with a U-shaped white patch that includes a central, less distinctly marked dark area. The beak, legs, and feet are a stark black, and when in flight, its feet do not project beyond the tail.

Identification Tips

When attempting to identify Ainley's storm petrel, look for its fairly long wings with blunt tips and a moderately long, forked tail. The white rump with the central dark area is a key distinguishing characteristic. In flight, note that the bird's feet do not extend past the tail, a trait that can aid in identification from a distance.

Habitat

Ainley's storm petrel is a pelagic bird, spending much of its life over the open ocean, far from land. Its habits are thought to be similar to those of Leach's storm petrel.

Distribution

This species is known to breed on three islets off the southern end of Guadalupe Island, Mexico, during the winter months. Its range extends southward to the Galápagos Islands.

Behaviour

Ainley's storm petrel exhibits nocturnal tendencies at its breeding colonies. It nests within crevices and burrows, providing shelter and seclusion. Outside the breeding season, it roams the open seas, likely engaging in similar behaviors to its relative, Leach's storm petrel.

Breeding

Breeding occurs in the winter on Guadalupe Island, with the species favoring the seclusion of crevices and burrows for nesting sites. The total global population is estimated to be only a few thousand birds, indicating a limited breeding population.

Similar Species

Ainley's storm petrel bears a resemblance to other storm petrels, such as Townsend's storm petrel and Leach's storm petrel. However, slight differences in plumage and structure, as well as its unique breeding season, help to differentiate it from its congeners.

Conservation status

The IUCN has classified Ainley's storm petrel as Vulnerable. This status reflects concerns about its limited breeding range and the small size of its overall population.