ID Keys: Dark overall, pale gray bar on upper wings, paler rump than
rest of body, notched tail
Tristram's
Storm-petrel, also sometimes called the Sooty Storm-petrel, has a normal
range in the north Pacific ocean, typically in tropical areas. In
North America, they are known for a handful of records off the west coast of
the U.S., including a bird in the Farallon Islands and at Santa Rosa Island
off the coast of California. The species mostly breeds in the Hawaiian
Island chain, as well as a few islands off the coast of Japan. They
have a small breeding range to begin with, and the introduction of rats and
other introduced species on some of their former breeding islands has
further reduced suitable breeding habitat. In Japan, breeding is now
reduced to 3 very small, rat-free islands. In Hawaii, it is thought
they once had a greater breeding distribution such as on Midway Island, but
the introduction of rats likely decimated any breeding populations there.
The global population of Tristram's Storm-petrel is likely below 30,000
birds. They are protected in the Hawaiian Islands and current
populations are considered stable, but they are still considered a
"threatened" species.
The few birds found off the coast of California may be an indicator of
warming ocean currents in the region, given the species preference for
warm-water areas outside of the breeding season.
Habitat
Outside of the breeding season they can
be found widely over warm, tropical or subtropical waters of the central and
western Pacific Ocean. During breeding season, they are found on small
islands where introduced species such as rats or cats are not a problem.
Diet
Diet: Mostly feeds on fish and squid, as well
as crustaceans and insects.
Behavior
Forages mostly at night, gliding close
to the water's surface searching for food items. "Patters" on the
water surface as do other storm-petrels.
Nesting
Colonial nester. Nests are burrows
dug in sandy areas, in rocky crevices, or under a clump of vegetation.
Young typically do not fledge until 10 to 12 weeks after hatching.
Migration
Breeds in the winter on the Hawaiian
Islands and a few invasive-free small islands of Japan. Outside of the
breeding season, they can range widely across the Pacific Ocean, staying
over warmer tropical and sub-tropical waters.
The IUCN lists the
Tristram's Storm-petrel as "Near Threatened". However, breeding
locations in the Hawaiian Islands are protected, and the species is
currently considered to have a stable population. The eradication of
introduced rats and other species may aid the Tristram's Storm-petrel.
Rats have now been exterminated from Midway atoll, and while breeding has
not been confirmed, Tristram's Storm-petrels are now being caught in
mist-netting operations there.
