General
Leach's Storm-Petrel: Medium-sized storm-petrel with dark brown body and white rump; undertail feathers form a contrasting horseshoe, but this conspicuous mark varies. Many birds only show a partial horseshoe or have a completely dark bar that divides it into two lateral patches. Wings are dark with pale gray-brown bar on upperwings; underwings are usually black, sometimes with a contrast between the more brown greater coverts and the more black secondaries. Tail is dark and forked. Bill, legs and feet are black. Sexes and juveniles are similar.
The Leach's Storm-Petrel now has two subspecies, the Townsend's Storm-Petrel and Ainley's Storm-Petrel. Split in 2016 by the American Ornithologist Union. Both are outside of north America.
Range and Habitat
Leach's Storm-Petrel: Breeds along sea coasts and offshore islands from Aleutians south down the Pacific coast to Baja California; also in western Pacific and north Atlantic from Labrador south to Maine and Massachusetts. Spends winters mainly in tropical seas. This species is pelagic and only comes ashore to breed.
Breeding and Nesting
Leach's Storm Petrel: These petrels nests in colonies close to the sea in well concealed areas such as rock crevices, shallow burrows or even logs. One dull white egg, occasionally marked with red purple, is laid in a shallow burrow lined with leaves and grass. Incubation ranges from 38 to 46 days and is carried out by both parents.
Foraging and Feeding
Leach's Storm-Petrel: These petrels vary their diet geographically and seasonally, depending on the available prey, which include fish such as cod and rockfish, myctophids, squid, octopus, and crustaceans including euphausiids, decapods, amphipods, isopods, mysids, copepods and jellyfish. They feed by pecking at individual organisms while hovering over the surface and occasionally pattering on it.
Vocalization
Leach's Storm-Petrel: Gives a variety of sharp tickling notes ending in a slurred trill.
Similar Species
Leach's Storm-Petrel: Wilson's Storm-Petrel has whiter rump, squared tail, and yellow feet often protruding beyond tail. Band-rumped Storm-Petrel has an undivided rump patch. Black Storm-Petrel has dark rump.