[order] PROCELLARIIFORMES | [family] Hydrobatidae | [latin] Oceanodroma tristrami | [authority] Salvin, 1896 | [UK] Tristrams Storm-petrel | [FR] Oceanite de Tristram | [DE] Tristam-Wellenlaufer | [ES] Paino de Tristram | [NL] Tristrams Stormvogeltje
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.
Tristram’s Storm-Petrel is mostly sooty-brown with a distinct bluish or grayish cast in fresh plumage. Upperwing coverts are paler, forming a prominent diagonal bar. It is slightly larger than Black and Markham’s Storm-petrels and much larger than Leach’s or Swinhoe’s Storm-petrels. Matsudaira’s Storm-petrel is browner, with white on outer primaries of upperwing and a less pronounced diagonal bar. Bare parts are black.
Listen to the sound of Tristrams Storm-petrel
Copyright remark: Most sounds derived from xeno-canto
Pacific Ocean : Northwest. Oceanodroma tristrami breeds in the Hawaiian archipelago (USA), on Nihoa (2,000-3,000 pairs), Necker, French Frigate Shoals (max 280 pairs), Laysan (500-2,500 pairs), Pearl and Hermes Reef (1,000-2,000 pairs), and may also breed on Midway, Lisianski and Kure. It also breeds on small predator-free islets of the Bonin and Izu Islands.
Islands in Hawaii and Japan, which include both low-lying coralline sand islands and high volcanic islands. For nesting, prefers recesses in rock scree, under mined guano piles, or burrows excavated under vegetation. Outside the breeding season it is pelagic.
Nest sites on Laysan included earthen burrows, dense vegetation and rocky crevices. Tristram’s Storm-Petrel colony sites in French Frigate Shoals lacked rocky crevices and dense vegetation?all nest sites there were earthen burrows. It nests, however, usually in burrows in sand or guano, under clumps of vegetation or in recesses in scree. In Hawaii, first egg laying occurs in December with the last chicks fledging in June. Tristram’s Storm-Petrels likely do not brood their chicks for more than two to three days after hatching. The incubation period 39-55 days. Chicks fledged as young as 74 days and as old as 100 days.
Tristram’s storm-petrel feeds by dipping prey from the ocean’s surface on the wing, often pattering the water with feet. The diet includes fish, squid, coelenterates, crustaceans, and insects.
Video Tristrams Storm-petrel
copyright: Peter Fraser
This species is classified as Near Threatened because it is thought to have a small breeding range. A higher level of threat classification might be justified if the range size is confirmed and found to be declining.
The most serious threat to the species is the potential introduction of rats or other predators to any of its primary breeding sites: a large population of O. tristrami which bred on Torishima Island until the early 1960s was apparently exterminated by introduced cats and rats, and potentially large colonies could have been extirpated from the Northwestern Hawaiian Islands for the same reason. It may also be susceptible to marine pollution, with tiny plastic pellets and fragments found in one-third of the stomach samples from the Northwestern Hawaiian Islands. Large-scale human activities near its colonies, including the presence of large numbers of ships, could increase mortality due to its attraction to lights. Predation and irritation by introduced ants could be problem for the species.
Fairly sedentary. Thought to disperse only over adjacent seas; W populations may move short distance N up coast of Japan.