Ashy storm petrel

The tubenose

Published measurements include mass about 38.1 and wingspan about 42.5.

Range and habitat

It breeds colonially on islands off the coasts of California and Mexico, and is one of six species of storm petrel that live and feed in the rich California Current system.

Ashy storm petrels breed on 17 islands in the northeast Pacific, principally off the coast of California, but among them a few sites off the coast of northwestern Mexico. Half the world's population nests on the Farallon Islands near San Francisco.

GBIF currently lists 43,468 occurrence points. Those points follow where people logged the taxon — museum drawers and surveys included — not a closed range boundary.

Pins are Wikidata “endemic to” fields. Orange dots, when present, are GBIF occurrence tiles — survey bias included.

Diet and breeding

It is a gregarious bird at sea, feeding nocturnally on cephalopods, fish (particularly the deep-sea myctophids, that rise to the sea's surface at night) and euphausiid krill such as Thysanoessa spinifera, that also swarm at the surface. Ashy storm petrels nest in rock burrows on offshore islands, returning to the nests at night.

The species has a long breeding cycle, laying eggs in May and fledging in October, although timing varies greatly, more so than in most other storm petrels. Some pairs may have a chick that is half grown when other pairs are still laying. Like in many other seabirds, pairs show both mate and site fidelity, mating in the same pair with the same mate for many years and nesting at the same burrow, despite the pairs spending their lives out of the breeding season separate from each other, and despite the fact that many individuals might seem to compete for burrows at the nesting colonies.

In crisis

Other breeding islands include the eight Channel Islands of California and a small population on Mexico's Coronados. The world population is estimated to be around 10,000 birds, 8,000 of them breeders, with the Farallon population having declined by one-third between 1972 and 1992. It is threatened by western gull and burrowing owl predation, illumination from fishing boats, introduced predators such as rats and feral cats, and pollution.

Sea-level rise will also threaten certain nesting sites that would be located too close to water.

Ashy storm petrel is Endangered on this catalog because that is the IUCN category stored on Wikidata. Confirm the official criteria and any later count on iucnredlist.org.

Sources

Written for this catalog from the English Wikipedia article on Ashy storm petrel, Wikidata item Q28114516 and GBIF occurrence geography. Family and order context is original field-guide writing about the group, not a copied assessment of this one species. Wikipedia text is CC BY-SA. Not an IUCN assessment. Counts, when quoted, can change — confirm them on the recovery programme and on iucnredlist.org.