Ashy Storm-petrel (Oceanodroma homochroa)

Ashy Storm-petrel

Subspecies

Genus	Species	subspecies	Region	Range
Oceanodroma	homochroa		PO	ne

Genus

Storm-petrels are rather small and often dark colored tubenoses with a world wide distribution. All have fine black bills with very pronounced tubes. Storm Petrels are separated in two groups: the long legged, Southern Hemisphere birds subfamily Oceanitinae and the shorter legged species of more northern seas the subfamily Hydrobatinae. The first groups shows more morphological differences than the second. The genera are characterised on colour patterns, the condition of the nasal tubes, tail shape, structure of claws and proportions of the leg bones. The genus Oceanodroma consists of medium-sized petrels; plumage dark or greyish, often with pale rumps; tail more or less forked; tarsus short , middle toe with claw and scutellate; claws narrow.

Physical charateristics

Separated from Black Storm-Petrel by smaller size, shorter wings, more fluttery flight. At very close range, head looks ashy, wings show light mottling underneath.

Listen to the sound of Ashy Storm-petrel

[audio:http://www.planetofbirds.com/MASTER/PROCELLARIIFORMES/Hydrobatidae/sounds/Ashy Storm-petrel.mp3]

Copyright remark: Most sounds derived from xeno-canto

recorded by UCSC CCAL

wingspan min.:	46	cm	wingspan max.:	48	cm
size min.:	20	cm	size max.:	21	cm
incubation min.:	44	days	incubation max.:	45	days
fledging min.:	82	days	fledging max.:	84	days
broods:	1		eggs min.:	1
			eggs max.:	1

Range

Pacific Ocean : Northeast. Oceanodroma homochroa breeds on a small number of island groups and offshore rocks within the California Current System, the northernmost being off Mendocino County, California and the southernmost at Los Coronados Islands off northern Baja California, Mexico.

Habitat

Open ocean. During summer, favors relatively cool waters of the California Current, feeding mainly just off the edge of the continental shelf. In fall, concentrates where deep waters of the Monterey Submarine Canyon come relatively near shore in Monterey Bay. Nests
on rocky islands with abundant crevices for nesting.

Reproduction

Breeds in colonies on offshore islands. Active at colonies only at night, arriving there just after dark and departing before first light. Some adults may visit colony every month of year. At Farallon Islands off central California,
nesting is not synchronized; egg-laying may occur any time late April to mid-July, rarely to September. Before eggs are laid, both members of pair may spend time in nest chambers, giving trilling and twittering songs.
Nest: Site is in natural cavity or crevice under rock piles, under driftwood, or in old burrow of other species; usually no nest lining added.
Clutch 1. White or with faint reddish brown dots. Incubation is by both sexes, averages about 44 days.
Young: Probably both parents feed young, by regurgitation. Young leaves nest and goes to sea on average about 76 days after hatching.

Feeding habits

Probably crustaceans, fish. Diet is not well known. Probably includes small fish, crustaceans, perhaps algae. Once reported to feed heavily on the larval stage of spiny lobster off southern California.

Behavior: Forages mostly by hovering or skimming low over water and taking items from surface.

Conservation

This storm-petrel qualifies as Endangered because studies suggest that its small population may be declining very rapidly over three generations (48 years) owing to a variety of threats.

Migration

At sea from northern California (Point Reyes) to Baja California. Breeds on Farallon, Channel, and Coronados islands. Summers offshore within dash line. bMigration:
In fall, a high percentage of total population concentrates on Monterey Bay, California. Some may be present in California waters at all seasons, but at northern end of range is least numerous in early winter.

Distribution map

Ashy Storm-petrel distribution range map

Planet of Birds