Nombre en español: Paíño de Galápagos
Nombre en inglés: Wedge-rumped Storm-Petrel
Nombre científico: Hydrobates tethys
Familia: Hydrobatidae
El paíño de las Galápagos (Oceanodroma tethys) es una especie de ave procelariforme de la familia Hydrobatidae. Anida únicamente en las islas Galápagos (Ecuador), las islas Pescadores y San Gallán (Perú). Su área de distribución incluye las aguas costeras del occidente de América, desde Baja California en México hasta Chile.
Ave pelágica y marina que se reproduce en islas Galápagos e islas de la costa peruana. En Colombia puede ser vista en aguas de la Costa Pacífica. Su nombre Oceanodroma significa corredor de los océanos y deriva de las raíces griegas okeanos = océano y dromos = corredor. En la mitología griega Tethys era la diosa suprema del océano.
Tamaño y Forma
Mide de 18 a 20 cm. Ambos sexos similares. Es principalmente de color negro ahumado con un parche triangular en la rabadilla extenso, cuyo ápice llega casi hasta el final de la cola. También presenta cobertoras alares superiores pálidas formando una banda diagonal. Sus patas y dedos son negros. Los jóvenes son similares a los adultos.
Especies Similares
Es mucho más blanca en la rabadilla y en las cobertoras supracaudales que cualquier otro paíño. Podría confundirse con el Paíño de Elliot (Oceanites gracilis) pero se distingue de este por sus patas totalmente negras, no amarillas y vientre oscuro uniforme.
Diferencias Regionales
Se reconocen dos subespecies O. t. tethys y O. t. kelsalli, esta última en promedio más pequeña.
Subespecies
Se distinguen dos subespecies:
- Oceanodroma tethys kelsalli (Lowe, 1925)
- Oceanodroma tethys tethys (Bonaparte, 1852)
Distribución y Habitat
Se encuentra principalmente en las Galápagos, islas Pescadores y San Gallán del Perú y vaga hasta el centro de Chile y ocasionalmente al norte hasta California. En Colombia se encuentra en aguas de la Costa Pacífica.
Es un ave marina y pelágica que generalmente se le encuentra lejos de la línea de costa. Durante el periodo reproductivo se le encuentra en acantilados rocosos y campos de lava en islas remotas.
Alimentación
Se alimenta principalmente de peces pequeños, calamares y crustáceos.
Reproducción
Forma colonias reproductivas en las Galápagos principalmente entre mayo y junio. Anida en cavidades rocosas o bajo la vegetación en donde pone 1 huevo el cual incuban ambos padres en turnos de cinco días. Las crías salen por primera vez del nido cerca del día 76 después de la eclosión.
Comportamiento
Cuando capturan sus presas lo hacen en la superficie del agua o mediante inmersiones cortas mientras están sentados en el agua. Su vuelo es deliberado y directo y en ocasiones pedalea en el agua. En determinadas temporadas del año muchos individuos se dispersan siguiendo la corriente del Humboldt.
Wedge-rumped storm petrel
The wedge-rumped storm petrel (Hydrobates tethys) is a storm petrel. It breeds in the Galápagos Islands and on the coast of Peru. It was formerly defined in the genus Oceanodroma before that genus was synonymized with Hydrobates.
The Wedge-rumped Storm-Petrel, formerly known as the Galapagos Storm-Petrel is a small species and appears to be most closely related to the Least Storm-Petrel (Halocyptena microsoma). Once confirmed it may then require the Wedge-rumped to be shifted to the Halocyptena genus. The present English name highlights the triangular shape of the white rump patch, in itself distinctive. Quite unusual is that the Wedge-rumped Storm-Petrel is the only storm-petrel that visits its colonies during the day, at least in the Galapagos population. On the well known Genovesa Island colony, Short-eared Owls (Asio flammeus galapagoensis) is a major predator of the storm-petrels. It is hypothesized that they conduct diurnal visits to the colony because they are largely nocturnal foragers. However, there is a separate subspecies (kelsalli) that breeds on islands off Peru and Chile in the Humboldt Current and these birds are typically nocturnal at the colonies as is the norm in the family. During the non-breeding season the species ranges north to at least central Mexico, and south to northern Chile.
Habitat
Marine and pelagic, normally occurring well offshore, except near colonies; only species that regularly visits colonies by day (Galapagos). Breeds on cliffs, lava fields or in stone walls on remote islands and offshore stacks.
Movement
Overall at-sea range is from 25º N (off Baja California) S to at least N Chile (10º S) and between coasts of mainland Middle and South America to at least 120º W; recorded year-round N to 23º N, being commonest storm-petrel around Revillagigedo Is, off W Mexico (e.g. in May), and is uncommon to fairly common in S Gulf of California (May–Aug at least), with single record of nominate tethys on land (in burrow) on Guadalupe I (late Jan). Some birds present throughout year at Galapagos, but most disperse following Humboldt Current, as does Peruvian population. Vagrant N to C California (where several reports in late Jul to early Oct at sea, and specimen of kelsalli from Jan found inland). At-sea non-breeding ranges of two races apparently differ, with kelsalli generally commoner inshore, e.g. off Costa Rica and Panama (where usually recorded May–Nov), mainly < 100 km from land, whereas nominate tethys tends to occur further offshore (> 100 km from land).
Diet and Foraging
Mostly small fish, cephalopods (e.g. squid), planktonic crustaceans and neustons caught on wing, by pattering and dipping, or by surface-seizing while sitting on the water. Occasionally takes sea skaters (Halobates spp.), small, fast-moving marine insects, but these do not appear to be regularly targeted prey. Feeds mainly at night. Sometimes follows ships. Usually occurs singly or in small groups, but occasionally recorded in dense flocks that number hundreds of birds, especially when scavenging at carcasses of marine mammals; also readily associates with other storm-petrels, especially H. melania and H. leucorhous, but also H. microsoma. Recorded joining mixed-species feeding frenzies, at which dolphins may also be present.
Sounds and Vocal Behavior
Two main call types described, a slightly screeching churr interspersed by two rapid squeaking notes, and a low purring call with a quiet “tchzee” at its heart.
Breeding
In Galapagos, many birds present at colony in most months, but laying mainly in May/Jun (thus season Mar–Sept), whereas in Peru eggs laid from at least mid Mar on Ferrol I, early Apr on Chao and Corcovado (all NC Peru), and early May on Pescadores Is, while even further S, egg-laying may occur as early as late Dec off NC Chile (Isla Grande). Diurnal at colonies in Galapagos, but nocturnal at colonies off Peru (14). Colonialvideo , at densities of up to 15 nests per 1 m² ; nests in rock crevices (including those in dry-stone walls) or under vegetation cover; crevice size in stone walls typically 240–420 mm (probably deeper in natural sites) with entrances of 25–240 mm; natural crevices on Isla Grande ranged from 7–16 cm in height (11·3 ± 2·7), 15–48 cm in width (25·3 ± 10·3), and 20–53 cm in depth (33·2 ± 8·5). Clutch single white egg, mean size and mass 27·8 mm × 20·6 mm, 5·2 g (nominate), or 20.3–27.4 mm × 18.1–20.3 mm (kelsalli), 5·1 g; incubation in stints of c. 5 days but overall duration unknown; chick brooded for c. 2 days and fed on at least 50% of days in nest; fledging c. 76 days (range 66–86 days). Overall breeding success c. 23%, although perhaps over-estimated, based on 193 eggs monitored on Galapagos, which produced 63 young, 45 to fledging. Adults on Genovesa (Tower) I predated by Short-eared Owls (Asio flammeus galapagoensis) at colonies, but competition for nest-sites reported to be more important cause of breeding failure there.
Conservation Status
Conservation status on BirdlifeLC Least Concern
Not globally threatened. Overall population stated to probably exceed 500,000 individuals. Well in excess of 200,000 breeding pairs in Galapagos Is, where breeding confirmed to occur on Pitt (off San Cristóbal) Is, and possibly on Roca Redonda; exact numbers in Peru not known, but species is either presumed or known to breed on following islands or groups, from N to S, Chao, Corcovado, Ferrol, the Pescadores, San Lorenzo, San Gallán and La Vieja. Recent surveys located c. 100 pairs on Chao and Corcovado Is (Apr 2003) and at least 176 nests on Ferrol I (May 2006). Also recently discovered breeding on Isla Grande, off N Chile, albeit in small numbers. Suffers predation by Short eared Owl (Asio flammeus) in Galapagos; diurnal habits and location of breeding colonies make species particularly vulnerable to predation there. More research required, especially in Peru.
Fuentes: Wikipedia/eBird/xeno-canto/Wikiaves/Birds of the world
