Pterodroma cahow (Nichols & Mowbray 1916)

Pterodroma cahow^[1] a zo ur spesad evned eus ar c'herentiad Procellariidae.
Dibabet e oa bet da evn broadel gant Bermuda.

Anvet e voe Æstrelata cahow (kentanv) da gentañ-penn (e 1916)^[2] gant John T. Nichols (1883-1958) ha Louis L. Mowbray (1877-1952).

Ur gwir dakson Lazar an hini eo : bet adkavet e 1951 gant an daou skiantour stadunanat Robert Cushman Murphy (1887-1973) ha bermudat Louis Leon Arthur Mowbray ne oa ket bet adwelet abaoe ar bloavezhioù 1620. Ma soñje d'an evnoniourien e oa aet ar spesad da get da vat.

Doareoù pennañ

Boued

Bevañ a ra diwar kresteneged 'zo, pesked bihan ha stivell.

Annez

Emañ brosezat ar spesad en enezenn Nonsuch (Bermuda)^[3].

Liammoù diavaez

• (en) Pterodroma cahow war al lec'hienn BirdLife International.
• (en) Pterodroma cahow war lec'hienn an International Union for Conservation of Nature (IUCN).

Muioc'h a restroù diwar-benn

Pterodroma cahow

a vo kavet e Wikimedia Commons.

Notennoù ha daveennoù

El petrell de les Bermudes (Pterodroma cahow) és un ocell marí de la família dels procel·làrids (Procellariidae), d'hàbits pelàgics, cria a les illes Bermudes i després es dispersa pels mars del voltant.

Referències

Aderyn a rhywogaeth o adar yw Cahow (sy'n enw gwrywaidd; enw lluosog: cahowiaid) a adnabyddir hefyd gyda'i enw gwyddonol Pterodroma cahow; yr enw Saesneg arno yw Cahow. Mae'n perthyn i deulu'r Pedrynnod (Lladin: Procellariidae) sydd yn urdd y Procellariformes.^[1]

Talfyrir yr enw Lladin yn aml yn P. cahow, sef enw'r rhywogaeth.^[2] Mae'r rhywogaeth hon i'w chanfod yng Ngogledd America.

Teulu

Mae'r cahow yn perthyn i deulu'r Pedrynnod (Lladin: Procellariidae). Dyma rai o aelodau eraill y teulu:

Rhestr Wicidata:

Gweler hefyd

• Rhestr Goch yr IUCN

Cyfeiriadau

Cahow ist eine Weiterleitung auf diesen Artikel. Zur US-amerikanischen Eishockeyspielerin siehe Caitlin Cahow.

Verbreitungsgebiet

Der Bermuda-Sturmvogel (Pterodroma cahow) auch als Cahow oder Bermudasturmtaucher bezeichnet, ist ein seltener Seevogel aus der Gattung der Hakensturmtaucher (Pterodroma). Früher war er auf ganz Bermuda verbreitet, heute erstreckt sich sein Verbreitungsgebiet auf einige wenige rattenfreie Inseln.

Beschreibung

Der Bermuda-Sturmvogel erreicht eine Länge von 38 Zentimeter und eine Flügelspannweite von 89 Zentimeter. Die Haube, die die Augen mit umschließt, und die Oberseite sind braungrau. Auf dem Nacken befindet sich ein braunes Kragenband. Der Schnabel ist schwarz. Die Unterseite ist weiß, die Flügel sind weiß mit schwarzen Kanten. Im Flug ist er leicht mit dem größeren Teufelssturmvogel zu verwechseln.

Lebensweise

Küken eines Bermuda-Sturmvogels

Über die Lebensweise des Bermudasturmvogels ist nur wenig bekannt. Er ist nachtaktiv und folgt den Planktonschwärmen des Golfstroms. Die Brutzeit ist von Januar bis Juni. Das Gelege besteht aus einem einzigen Ei. Früher wurden die Eier in Erdhöhlen am Strand abgelegt. Doch Ratten haben die Kolonien auf kleine Felsinseln verdrängt, die nicht gleichermaßen optimal zum Brüten sind. Nach 51 bis 54 Tagen schlüpfen die Jungen, die nach 90 bis 100 Tagen flügge sind.

Gefährdung

Dieser Vogel war bereits den Seefahrern im 17. Jahrhundert bekannt. Als im Winter 1614/15 ein Schiff auf Bermuda landete, konnten die fast verhungerten englischen Siedler ihr Leben dadurch retten, dass sie die zutraulichen Sturmtaucher töteten. Aufgrund der eingeschleppten Säugetiere auf Bermuda und das Einsammeln der Eier war diese Art schnell verschollen. 1906 entdeckte der Ornithologe Louis L. Mowbray ein Exemplar des Bermuda-Sturmvogels und 1916 erfolgte aufgrund dieses Exemplars die wissenschaftliche Erstbeschreibung durch Mowbray und John Treadwell Nichols. Erst 1951 entdeckte man sechs Nester auf der Insel Castle Harbor und fotografierte sie. Insgesamt zählte man 18 Brutpaare. Damit galt diese Vogelart nach über 330 Jahren als wiederentdeckt. 1963 war er aber mit einem Bestand von nur 17 Brutpaaren einer der seltensten Vögel der Welt. Der Einsatz von DDT und anderen Insektiziden sorgten dafür, dass nur noch ein Teil der Eier fruchtbar war. Nach dem Verbot von DDT lag der Bestand im Jahr 1994 bei 90 Exemplaren. Aber auch diese Population war vor allem durch die Konkurrenz von anderen Seevögeln wie dem Weißschwanz-Tropikvogel aber auch durch die Zunahme von Wirbelstürmen bedroht. So zerstörte der Hurrikan Fabian im Jahre 2003 einen großen Teil der Brutpopulation. 2005 lag der Weltbestand bei 250 Vögeln. 2011 wurden 98 Brutpaare gezählt, die 56 Jungvögel aufzogen. 2012 waren es 101 Brutpaare.

Literatur

• John H. Sparks: Bedrohte Tierwelt. Delphin-Taschenbuch in Farbe Nr. 27, Delphin Verlag Stuttgart / Zürich 1974.
• F. Vester, A. W. Diamond, H. Stern, G. Thielcke: Rettet die Vogelwelt. Ravensburger Verlag, 1987.

Weblinks

– Sammlung von Bildern

• Fotos und Videos vom Bermuda-Sturmvogel (Pterodroma cahow) auf ARKive.org (Memento vom 6. Dezember 2018 im Internet Archive).
• BirdLife International: Species Factsheet – Pterodroma cahow
• BirdLife: Cahows bounce back as Bermudians build burrows (Memento vom 7. Juni 2007 im Internet Archive)
• Library of Congress early written records
• Lucinda Spurling's documentary film website (Memento vom 22. Juli 2012 im Internet Archive)
• Pterodroma cahow in der Roten Liste gefährdeter Arten der IUCN 2018. Eingestellt von: BirdLife International, 2018. Abgerufen am 16. September 2021.
• Videos, Fotos und Tonaufnahmen zu Pterodroma cahow in der Internet Bird Collection

The Bermuda petrel (Pterodroma cahow) is a gadfly petrel. Commonly known in Bermuda as the cahow, a name derived from its eerie cries, this nocturnal ground-nesting seabird is the national bird of Bermuda and can be found pictured on Bermudian currency. It is the second rarest seabird on the planet and a symbol of hope for nature conservation. They are known for their medium-sized body and long wings. The Bermuda petrel has a greyish-black crown and collar, dark grey upper-wings and tail, white upper-tail coverts and white under-wings edged with black, and the underparts are completely white.

For 300 years, it was thought to be extinct. The dramatic rediscovery in 1951 of eighteen nesting pairs made this a "Lazarus species", that is, a species found to be alive after having been considered extinct. This has inspired a book and two documentary films. A national programme to preserve the bird and restore the species has helped increase its numbers, but scientists are still working to enlarge its nesting habitat on the restored Nonsuch Island.

Diet and foraging

Cahows typically eat small fish, squid and shrimp-like crustaceans.^[2] They also predominantly feed in colder waters. Geolocator studies carried out between 2009 and 2011 confirmed that they primarily forage in two widely separated locations during the non-breeding season (July to October), between Bermuda, Nova Scotia and North Carolina, and to the north and northwest of the Azores archipelago. Special glands in their tube-like nostrils allow them to ingest seawater. These glands filter out the salt and expel it through sneezing.

Breeding

Initially they were superabundant throughout the archipelago, but because of habitat degradation and invasion of mammals, the bird's suitable nesting areas have dwindled to four islets in Castle Harbor, Bermuda, in the warm waters of the Gulf Stream, some 650 miles east of North Carolina. The cahow is a slow breeder, but excellent flier. It visits land only to nest and spends most its adult life on the open seas ranging from the North Atlantic coastal United States and Canada to waters off western Europe.^[3] After 3–4 years at sea, males return to breeding islands to create nests.

Breeding season takes place during January and June. They nest in burrows and only the ones that can be in complete darkness are chosen. Females return after 4–6 years at open sea looking for a mate; the females lay one egg per season. 40% to 50% fail to hatch. Eggs are incubated by both parents and take 53–55 days to hatch. Hatching occurs between May and June. Cahows mate for life and typically return to the same nest each year.

In a first of its kind, a high school science project engaged in a remote study via live webcam using Cornell Lab's Cahowcam.^[4][5] It described incubation behavior of this species.^[4] The study found that sexes shared incubation duties equally; sedentary behaviors of incubating parent included resting (56% of observed time), sleeping with head tucked back (31%), preening (5%), and nest maintenance (3%); nest attentiveness was high, with the egg left unattended only 1.5% of the observed time; and the incubating parent faced the nest entrance 49% of the time.^[4] Breathing rates and head shake movements were also measured for the first time in a seabird. Both parents were in the nest together for only 11 of the 55 days (19%) of observations.^[4] A parent was observed burying the inviable egg on the 68th day since laying.^[4]

History

The Spanish sailors of the 1500s used Bermuda and its surrounding islands as a waypoint to the Americas. At that time, cahows were abundant and formed dense, noisy colonies. These sailors, as Diego Ramirez wrote in 1603, would take up to 4,000 birds a night for food.^[2][6] In addition to eating birds, conquistadors brought hogs to the island to sustain themselves over their voyage. These hogs decimated the ground-nesting cahow, rooting up their burrows, eating eggs, chicks and adults and disrupting their breeding cycle.

Following the Spanish visits Bermuda, the English ship Sea Venture was wrecked on the island in 1609. Those men that were shipwrecked culled the fattest individual petrels and harvested their eggs in abundance, especially in January when other food sources were diminished. Although most of the survivors would continue on to Jamestown in two newly-built vessels, this shipwreck began the permanent settlement of Bermuda by the English as three men remained and were joined by others in 1612 when Bermuda was officially added to the territory of Virginia.

Bermuda's colonization by the English introduced species like rats, cats and dogs, and mass killings of the birds for food by these early colonists devastated their numbers. The remaining cahow population also decreased due to widespread burning of vegetation and deforestation by the settlers during the first 20 years of settlement. Despite being protected by one of the world's earliest conservation decrees, the governor's proclamation "against the spoyle and havocke of the Cohowes", the birds were thought to have become extinct by the 1620s.^[6][7]

Subsequent sightings of the cahow were believed to be confusion with the similar Audubon's shearwater.^[8][2] In 1935, William Beebe of the New York Zoological Society had hopes of rediscovering the bird.^[6] By June he was presented with an unidentified seabird that had struck the St. David's lighthouse in Bermuda.^[2][6] The bird was then sent to American ornithologist Robert Cushman Murphy of The American Museum of Natural history in New York.^[2][6] He identified the bird as a Bermuda petrel.^[6] Six years later, Bermudian naturalist Louis L. Mowbray received a live Bermuda petrel that had collided with a radio antenna tower.^[6] The bird was released after rehabilitation two days later.^[6][9]

After a bird that died flying into a lighthouse was identified as a cahow, in January 1951,^[8] 18 surviving nesting pairs were found on rocky islets in Castle Harbour by Murphy and Mowbray and with them was a 15-year-old Bermudian boy, David B. Wingate, who would become the primary conservationist in the fight to save the bird.^{[2][6][7][10]}

Conservation

David B. Wingate devoted his life after that to saving the bird. After university studies and other work, in 1966 Wingate became Bermuda's first conservation officer. He undertook work to address various threats to the Bermuda petrel, including the eradication of introduced rats on the nesting islands and nearby islands, and addressed nest-site competition with the more aggressive, native white-tailed tropicbird Phaethon lepturus catsbyii, which invaded petrel nest burrows and killed up to 75% of all chicks. Following the design and installation of specially sized wooden "baffler" burrow entrance covers, which allowed the petrels to enter but excluded the larger tropicbirds, there has been essentially no further chick loss from this cause.

Wingate also initiated the ecological restoration of Nonsuch Island, located near the Bermuda petrel breeding islets. Nonsuch was a near desert after centuries of abuse, neglect and habitat destruction.^[11] The measures that had to be taken weren't just for conserving what was left but also to recreate what had been lost, and thousands of endemic and native plants, including Bermuda cedar (Juniperus bermudiana), Bermuda palmetto palm (Sabal bermudana) and Bermuda olivewood (Cassine laneanum), were propagated and planted out on Nonsuch to recreate the original forest ecosystem that once covered Bermuda, but which was almost entirely lost through disease and clearing for agriculture, shipbuilding and residential development. In total, almost 10,000 individual native and endemic plants of over 100 species were planted on Nonsuch starting in 1962, and have since developed into a well-established closed-canopy forest, similar to early accounts of what was found on Bermuda by the earliest settlers in the 1600s. Wingate's goal was to restore the habitat on Nonsuch Island so that it could eventually serve as a viable nesting site for the species.

Even after retirement, Wingate designed and donated artificial plastic nest boxes to the Cahow Recovery Project, funded by the Bermuda Audubon Society. These nests were an effort made toward assisting the recovery of the Bermuda petrel, which normally nest in deep soil burrows or rock crevices but suffered from a shortage of suitable nest sites and soil for the birds to burrow in on the original nesting islets. Artificial concrete burrows have been used for many years to provide additional nesting opportunities for the birds, but are very labor-intensive to construct, requiring 400-800 lbs of concrete each. The new nest boxes were designed to meet the birds nesting needs, and it is hoped that they will assist in the recovery of the cahow for its future survival.^[12]

David Wingate retired in 2000, after which Jeremy Madeiros became the Bermuda Government terrestrial conservation officer, taking over the management of the Cahow Recovery Program and the Nonsuch Island Living Museum Project.^[13] Madeiros carried out a review of the status of the Bermuda petrel, identifying erosion of the four small original nesting islets due to hurricane damage and sea level rise as the single largest threat facing the species. A banding program for both fledgling and adult petrels was initiated in 2002, and by 2015 had resulted in over 85% of all Bermuda petrels being fitted with identification bands, enabling positive identification of individual birds through their breeding lifespan. Madeiros published a recovery plan for the Bermuda petrel, which provided guidelines and objectives for the management of the species, in 2005.^[14]

Translocation project

It was recognized that the four original tiny nesting islets, which were the only nesting locations for the Petrel and which totaled only 1 hectare (2.4 acres) in area, did not provide sufficient habitat for the species to fully recover. Madeiros, assisted by the Australian petrel specialist Nicholas Carlile, proposed and carried out a translocation project to re-establish a nesting population of Bermuda petrel on Nonsuch Island, which at 6.9 ha (16.5 acres) was much larger and more elevated that the original nesting islets, offering safety from erosion and hurricane flooding and providing room for potentially thousands of nesting pairs. In 2004, the trial year of the project took place with 14 chicks translocated 18–21 days before fledging from the original nesting islets to a group of artificial concrete nest burrows constructed on Nonsuch,^[10][15] where they were fed fresh squid and anchovies and monitored every day until departure, with all fledging successfully. In 2005, 21 chicks were translocated, with all again fledging successfully by mid-June.^[15] This project was continued for a total of five years, with 105 chicks in total being translocated, of which 102 fledged successfully out to sea.^[16]

Breeding on Nonsuch Island

Bermuda petrel chick

The first translocated Bermuda petrels returned when mature to Nonsuch Island in February 2008.^[17] The first petrel egg on Nonsuch Island in more than 300 years was laid in January 2009, and the resultant fledgling departed in June of the same year. A total of 49 of the original 102 translocated birds had been confirmed as returning to the nesting islands by 2015, of which 29 had returned to Nonsuch itself. This project has been successful in establishing a new nesting colony on Nonsuch, which by 2016 had grown to 15 nesting pairs. This colony had already produced 46 successfully fledged chicks between 2009 and 2016.^[18]

Based on the success of the first translocation project, Madeiros started a second translocation project in 2013 at a different location on Nonsuch, to establish a second colony and foothold for the Bermuda petrel on that island. During the first three years of this second project, a total of 49 near-fledged cahow chicks had been translocated to the "B" colony site, with 45 successfully fledging out to sea. In 2016, the first of these birds, translocated as a chick in 2013, returned and paired up with a non-translocated bird in a burrow at the original translocation colony on Nonsuch.

A Sound Attraction System was also set up in 2007 to help encourage returning translocated birds to stay and prospect on Nonsuch, and overcome any tendency for young birds to be attracted back to the activity at the original nesting islets.^[16]

Thanks to the conservation efforts over the past five decades and extensive legal protection, the population of the Bermuda petrel has risen from 17 to 18 breeding pairs producing 7-8 fledged chicks in 1960 to 132 breeding pairs producing 72 fledged chicks in 2019. The main threats for the future of the bird is still the lack of a suitable breeding sites,^[10] with 80% of the Bermuda petrels nesting in artificial burrows, and ongoing erosion of the original smaller nesting islets due to hurricane impacts and sea-level rise. Category 3 Hurricane Fabian destroyed about 15 nesting burrows in 2003, and damage to most of the remainder required urgent repair and construction of replacement burrows.^[10][15] In 2010, Hurricane Igor caused further extensive damage to nest burrows on the original islets, and in 2014, Category 2 Hurricane Gonzalo, a late-season hurricane, killed 5 nesting pairs that had already returned on the smaller nesting islets. The global population of this bird in 2015 was about 300 individuals. A cahow was captured in a burrow and ringed on Vila islet, Azores, in November 2002.^[19] It was recaptured there in November 2003 and December 2006.^[20] Another individual was seen off the west coast of Ireland in May 2014, the furthest the species has ever been seen from Bermuda.

CahowCam Outreach Project

Starting in 2011 the "CahowCam" project was launched by the Bermuda-based LookBermuda / Nonsuch Expeditions Team in partnership with the Department of the Environment and Natural Resources.^[5] Since then it has been live streaming infrared video from specially adapted artificial nesting burrows from Nonsuch Island Translocation Colony A using specialized cameras and lights custom built by Team Leader Jean-Pierre Rouja. In 2016 they partnered with The Cornell Lab of Ornithology bird-cam team resulting in over 20 million minutes of CahowCam footage being watched in the following 3 seasons.^[5][21]

Habitat restoration

Cahows, being a recovering Lazarus species, need special attention in order to support recovery and population growth. All nesting and nearby islands are strictly protected as part of the Castle Islands Nature Reserve, and landing by the public is prohibited except by special permission in the company of the conservation officer. This area is also designated as an international I.B.A. (Important Bird Area), in recognition of containing the entire world population of Bermuda petrel, and up to 20% of the North Atlantic population of white-tailed tropicbird. These islands are maintained rat-free by an annual baiting program, and domestic animals are prohibited from landing on all islands in the reserve. In addition, there is an ongoing management program to eradicate non-native invasive plant species on all of the reserve islands, coupled with plantings of native and endemic plant species, many of which are also endangered. Several of the nesting islands are also the subject of an ecological restoration project, to restore them as examples of the terrestrial plant and animal communities once found on, but now largely lost from, the rest of Bermuda.

Other conservation issues

Though the Bermuda petrel's population has explicitly increased and it is projected that the population will double every 22 years, there are still clearcut inhibitors on its path to recovery. The petrel's vulnerability has drastically increased due to substantial damage to its habitats and nesting sites by tropical storms and climate change. The predicted future increase of category 4 and 5 tropical storms pose an imminent threat to the petrels' long-term survivability. Tropical storms also aid the long-term effect of erosion of their surrounding habitat which hamper conservation efforts. As a solution, there is research going into finding another suitable area to make the artificial nesting places. Its recovery has been hampered by competition from white-tailed tropicbird (Phaethon lepturus) for nest-sites^[7] and predation of subadults by a single snowy owl (the first ever recorded in Bermuda) on Nonsuch Island, which was eradicated after having eaten 5% of the population. Light pollution from a nearby airport and a NASA tracking station adversely affects nocturnal aerial courtship.^[16]

Another major issue with nests is competition with other birds in the area. To address this problem, artificial dome nests were created for tropicbirds along areas, not used by the Bermuda petrel, and by applying wooden baffles over the entrances of petrel burrows. These baffles only allow petrels to enter, keeping the competition of tropicbirds out. Another factor may be that the cahow will have an increased risk of extinction because of restricted ranges, small population sizes, and lower genetic diversity. Additionally, the characteristic philopatry of petrel species may mean that birds continually return to the same high-mortality breeding sites year after year.^[22]

Rats also swam to one breeding island in April 2005, but were successfully eradicated within two weeks without loss to the cahows. Unfortunately this pattern appeared to be repeat in March 2008, with five chicks killed on one of the nesting islets. Immediate baiting produced a dead black rat (Rattus rattus). However, as the islands were all baited at the beginning of the nesting season, this incident pointed out the need for constant vigilance of reintroduction and a requirement to provide fresh bait on the islands throughout the nesting season.^[16] This was underlined by further invasions of some of the nesting islands, including Nonsuch Island, in 2014 and 2015, although this time without loss to the birds.

References

La Bermuda petrelo, Pterodroma cahow, estas malgranda marbirdo de la grupo de petreloj. Komune konata en Bermudo kiel la Cahow, nomo devena el ties timegigaj krioj, tiu noktula surgrundonestumanta petrelo estas endemio kaj la nacia birdo de Bermudo, kaj simbolo de espero por konservado de la naturo. Ĝi estis supozita formortinta dum 330 jaroj. Ties spektakla malkovro kiel "lazara specio", tio estas, kiel specio trovita viva post esti konsiderata formortinta dum jarcentoj, inspiris al dokumentariaj filmofaristoj.

Reproduktado

Dekomence superabunda tra la tuta arkipelago, la Bermuda petrelo estas malrapida reproduktulo, sed lerta fluganto, kaj pasas sian vivon de plenkreskulo en malferma maro. Kiam ĝi estas kvinjaraĝa ĝi revenas al sia iama nestoloko kaj ekreproduktiĝas: la ino demetas ununuran ovon ĉiun sezonon. Bermudaj petreloj pariĝas porvive.

Historio kaj konservado

La noktulaj krioj de la Bermuda petrelo malpermesis la fruajn hispanajn maristojn setliĝi sur la insuloj kiuj estis evitataj pro superstiĉo, ke la insuloj estis loĝataj de diabloj. Anstataŭe ili metis surborde porkojn kiel vivanta manĝo por bezonontaj preterpasontaj ŝipanoj, kaj tiele ekis la formorto de la Bermuda petrelo. Sekve de la koloniigo de Bermudo fare de la angloj, enmetitaj specioj kiaj ratoj, katoj kaj hundoj, kaj amasmortigado de tiuj birdoj fare de fruaj kolonoj dekonigis la nombrojn. Spite protekton pere de unu el plej fruaj konservoleĝoj de la mondo nome la proklamo de la Guberniestro de Bermudo "against the spoyle and havocke of the Cohowes" (kontraŭ la rabado kaj formorto de la petreloj), tiuj birdoj estis supozitaj kondukitaj al formorto ekde la 1620-aj jaroj.

En 1951, 18 survivintaj nestoparoj estis trovitaj sur rokaj insuletoj en Castle Harbour fare de usona ornitologo Robert Cushman Murphy kaj de bermuda naturalisto Louis L. Mowbray. Kune en la veturo estis 15-jaraĝa bermudano nome David B. Wingate, kiu ekde tiam dediĉis sian vivon al la savo de tiu birdo kaj en 1966 iĝis la unua bermuda konservadisma funkciulo. Wingate planis programon por konstrui cementajn nestotruojn kaj ellignajn strukturojn por la nestotruaj tuneloj por elteni for la iome pli grandajn kaj konkurencajn Blankvostajn tropikbirdojn, kaj restaŭris la najbaran insulon Nonsuch por ke ĝi estu futura ebla bazo por tiu nearktisa specio.

Ĝuante leĝan protektadon, la specio komencis rekuperiĝi; la ĉefa minaco por la futuro estas manko de taŭga reprodukta habitato. Uragano Fabian detruis multajn nestotruojn en 2003, kaj ĵuse la plej granda kaj ekologie restaŭrita insulo Nonsuch estas estanta repopulaciata de petrelidoj, kies translokiĝon oni malrapidigas por ke ili ricevu stampaĵon pri tiuj novaj lokoj.[1] Tiun laboron faras la nuna bermuda konservadisma funkciulo Jeremy Madeiros helpata de la petrelfakulo el Aŭstralio nome Nick Carlile. Tamen la tutmonda populacio de tiu birdo en 2005 estis nur de ĉirkaŭ 250 individuoj.

Referencoj

• BirdLife International (2006). Pterodroma cahow. Internacia Ruĝa Listo de Endanĝeritaj Specioj, eldono de 2006. IUCN 2006. Elŝutita 11a Majo 2006. Kriterioj kial tiu specio estas endanĝerita

Vidu ankaŭ

• Bermudaj subtropikaj koniferaroj

Polluelo de fardela de Bermudas.

El petrel cahow o fardela de Bermudas (Pterodroma cahow),^[2]​ es una especie de ave procelariforme de la familia Procellariidae endémica del archipiélago de Bermudas. Se creía extinto desde hace casi tres siglos, pero fue redescubierto a principios del siglo XX. Su redescubrimiento fue en 1951 cuando se encontraron 18 pares de nidos, siendo esta especie un taxón lázaro.

Referencias

Pterodroma cahow Pterodroma generoko animalia da. Hegaztien barruko Procellariidae familian sailkatua dago.

Erreferentziak

• World Bird Names

Ikus, gainera

• Pterodroma
• Procellariidae

Bermudanviistäjä (Pterodroma cahow) on uhanalainen, Bermudalla pesivä keskikokoinen ulappaliitäjälaji. Viime vuosina laji on palautettu Nonsuch Islandille, jossa se on aikoinaan pesinyt. Sen uskottiin kuolleen sukupuuttoon 1620-luvulla, mutta yksilöitä löytyi yllättäen vuonna 1951 lähes 300 vuoden tauon jälkeen. Azoreilla Vila Isletillä on tavattu sama yksilö eräässä pesäkolossa sekä marraskuussa 2002 että 2003.^[2] Hurrikaani Fabian teki pahaa tuhoa pesimäalueilla vuonna 2003. Vuonna 2005 maailmassa laskettiin olevan 250 yksilöä.^[1] Bermudanviistäjät pariutuvat koko elämänsä ajaksi, ja munivat vain yhden munan vuodessa.

Ulkonäkö ja koko

Bermudanviistäjä kasvaa 38 cm pitkäksi ja sen siipien väli on noin 89 cm. Se on päältä harmaanruskea, vatsapuolelta valkoinen. Alapuolelta näkyvät siipien tummat reunat ja valkoinen keskiosa. Sukupuolet ovat samanvärisiä.^[3]

Lähteet

Aiheesta muualla

• Audubon watchlist

Pterodroma cahow

Le Pétrel des Bermudes (Pterodroma cahow) est une espèce d'oiseaux de mer nocturnes de la famille des Procellariidae. C'est l'oiseau national des Bermudes et un symbole d'espoir pour la conservation de la nature.

La redécouverte sensationnelle, en 1951, de dix-huit couples nicheurs en a fait un taxon lazare. En effet, l'espèce n'avait pas été vue depuis plus de 300 ans. Le fait a inspiré un livre et deux films documentaires. Un programme national bermudien pour préserver cet oiseau et reconstituer l’espèce a aidé à accroître sa population. Les scientifiques travaillent toujours à agrandir son habitat de nidification sur l'île restaurée de Nonsuch Island (en).

Reproduction

Très abondant autrefois dans tout l'archipel, cet oiseau ne se reproduit que lentement mais son aptitude au vol est remarquable. Il passe sa vie adulte en haute mer. À cinq ans, il retourne à son ancien lieu de nidification et commence à se reproduire. Les femelles ne pondent qu’un œuf par saison. Les couples de cahows restent fidèles toute leur vie.

Histoire et conservation

Les cris nocturnes mystérieux de ces oiseaux ont d’abord empêché les premiers marins espagnols de s’établir dans ces îles par superstition, car ils pensaient qu'elles étaient habitées par des démons. Ils ont débarqué des porcs pour constituer une réserve alimentaire destinée aux bateaux de passage. Ces animaux ont perturbé les pétrels qui nichaient au sol et déstabilisé leur cycle de reproduction.

À la suite de la colonisation des Bermudes par les Anglais, les espèces introduites comme les rats, chats et chiens, ainsi que les massacres d’oiseaux par les premiers colons ont décimé un grand nombre d'oiseaux. Bien qu’ils fussent protégés par un des premiers décrets de conservation du monde, la proclamation du gouverneur « contre le massacre des Cohowes » (Cohow étant le nom de l'espèce en anglais), on croyait ces oiseaux disparus vers les années 1620.

Le 28 janvier 1951^[1], 18 couples nicheurs survivants ont été découverts sur des îlots rocheux à Castle Harbour (en) par l’ornithologue américain Robert Cushman Murphy et le naturaliste bermudien Louis L. Mowbray (en). Avec eux se trouvait David Balcombe Wingate, un jeune bermudien âgé de 15 ans. Par la suite, Wingate a consacré sa vie à la sauvegarde de l'espèce. Après avoir suivi des études universitaires et fait d'autres travaux, il est devenu aux Bermudes, en 1966, la première personne chargée officiellement de la protection des espèces.

Étudiant les oiseaux et leurs habitudes, il a mis en place un programme pour construire des abris en béton et en bois pour les terriers de nidification, afin d’empêcher d’entrer le Phaéton à bec jaune des Bermudes légèrement plus grand et qui lui faisait concurrence. Il a travaillé pour reconstituer l'habitat de l'île voisine de Nonsuch comme une base viable future pour l'espèce.

Bénéficiant d'une protection juridique, l'espèce a commencé à bien récupérer ; la principale menace pour l'avenir est le manque d'un habitat qui convienne à la reproduction. En 2003 l'ouragan Fabian a détruit un grand nombre d’abris de nidification. Les chercheurs sont en train de repeupler avec des jeunes l’île de Nonsuch, la plus grande et qui a été écologiquement restaurée, leur transfert a été calculé dans le temps afin qu'ils considèrent les lieux comme leur endroit d’origine et y reviennent pour la nidification. Ce travail a été entrepris par le chargé de la conservation aux Bermudes, Jeremy Madeiros, avec l’aide du spécialiste des pétrels l'Australien Nick Carlile. En 2005, la population globale de cet oiseau était d'environ 250 individus. Un pétrel des Bermudes a été capturé dans un terrier sur l'îlot de Vila, aux Açores, et bagué en novembre 2002^[2] ; il a été recapturé sur l'îlot en novembre 2003 et décembre 2006^[3]. Un autre individu a été observé au large de la côte ouest de l'Irlande en mai 2014, c’est l’endroit le plus éloigné des Bermudes où l'espèce ait jamais été vue.

Notes et références

Voir aussi

Références taxinomiques

• (en) Référence Congrès ornithologique international : (consulté le 29 mai 2015)
• (fr+en) Référence Avibase : Pterodroma cahow (+ répartition) (consulté le 30 juin 2015)
• (en) Référence Zoonomen Nomenclature Resource (Alan P. Peterson) : Pterodroma cahow dans Procellariiformes
• (en) Référence Tree of Life Web Project : Pterodroma cahow
• (en) Référence Paleobiology Database : Pterodroma cahow (Nichols and Mowbray 1916)
• (fr) Référence CITES : taxon Pterodroma cahow (sur le site du ministère français de l'Écologie) (consulté le 30 juin 2015)
• (en) Référence NCBI : Pterodroma cahow (taxons inclus)
• (en) Référence UICN : espèce Pterodroma cahow (Nichols & Mowbray, 1916) (consulté le 30 juin 2015)

Crédits

• (en) Cet article est partiellement ou en totalité issu de l’article de Wikipédia en anglais intitulé .

Bermudska burnica (lat. Pterodroma cahow) je morska ptica iz porodice zovoja.

Duga je 38 cm, a ima raspon krila od 89 cm. Čelo i prostor oko očiju su smeđosive boje. Vrat je smeđe boje. Kljun je crn.

Aktivna je noću. Sezona parenja je od siječnja do lipnja. Ženka polaže jedno jaje. Iz jaja se izlegnu ptići nakon 50-54 dana. Opernate nakon devedesetak dana.
Nedovršeni članak Bermudska burnica koji govori o pticama treba dopuniti. Dopunite ga prema pravilima Wikipedije.

Il petrello delle Bermuda (Pterodroma cahow Nichols e Mowbray, 1916) è un uccello della famiglia dei Procellariidi.^[2]

Noto alle Bermuda come cahow per i richiami lamentosi che emette, questo uccello marino notturno che nidifica al suolo è l'uccello nazionale delle Bermuda ed un simbolo di speranza per la conservazione della natura. Ritenuto estinto per 330 anni, è stato riscoperto solo nel corso del XX secolo.

Storia

Scoperta ed «estinzione»

Quando i primi coloni arrivarono nella Grande Bermuda nel 1609 vi trovarono un numero grandissimo di piccoli petrelli, che nominarono cahow per il loro richiamo. E strillavano di continuo; i primi esploratori chiamarono la Grande Bermuda l'«Isola dei diavoli» per il frastuono davvero infernale di quella moltitudine di uccelli. Anche se non sapremo mai quanti fossero in realtà, è stato stimato che prima dell'arrivo dei coloni dovevano essere presenti sull'isola mezzo milione di quegli uccelli dal ventre bianco, dal dorso nero e dall'apertura alare di una novantina di centimetri. Subito dopo l'insediamento dei coloni, una grave carestia costrinse i nuovi venuti a guardare con interesse ai cahow, che potevano essere catturati facilmente quando tornavano al nido, ed essere mangiati in gran numero. Insieme ai primi coloni arrivarono altri animali, come ratti, gatti e cani; l'impatto di questi nuovi predatori, combinato con gli estesi incendi, la deforestazione e la cattura da parte degli uomini di uccelli e uova da consumare come cibo, ridusse in misura grandissima la popolazione di cahow, sino a portarli sulla soglia dell'estinzione. Tre secoli sarebbero trascorsi prima che qualcuno sentisse parlare di nuovo di questi uccelli marini.

Riscoperta

Nel 1935, solo pochi anni prima che William Beebe compisse le prime storiche immersioni in batiscafo con Otis Barton, un ragazzo in bicicletta portò un uccello morto a Beebe nel suo laboratorio sulla Nonsuch Island, Bermuda. Beebe inviò l'uccello a Robert Cushman Murphy all'American Museum of Natural History di New York, e pubblicò immediatamente un articolo sulla sua «riscoperta» del cahow nel Bulletin of the New York Zoological Society. (Nel 1932, in Nonsuch, Land of Water, aveva sostenuto di avere udito il canto del cahow, ma probabilmente aveva udito la berta di Audubon [Puffinus lherminieri], che si riproduce anch'essa nelle Bermuda.) Un altro esemplare fu trovato ucciso di fresco nel 1941, e ci si rese conto che, dopo tutto, la Pterodroma cahow non era estinta come si riteneva, ma si riproduceva su qualche isola disabitata al largo delle Bermuda. I cahow, come la maggior parte dei petrelli, trascorrono la maggior parte della propria vita in mare e vengono a riva solo per nidificare e riprodursi, e quindi non sorprende che non fossero stati notati prima. Insieme a Louis Mowbray, curatore dell'Acquario delle Bermuda, R. C. Murphy, una delle principali autorità mondiali sugli uccelli marini, organizzò nel 1951 una spedizione alla ricerca di nidi di cahow. Ne trovò sette, cosa che condusse a un programma di protezione e di sostegno patrocinato dalla New York Zoological Society (Murphy e Mowbray, 1951).

Conservazione

Nel 1961 furono localizzate sulle Castle Harbour Islands diciotto coppie di cahow in età riproduttiva: l'intera popolazione impegnata nella riproduzione a quell'epoca. Il governo delle Bermuda dichiarò la Nonsuch Island una riserva per la protezione dei cahow, e ne allontanò tutti i potenziali predatori. Si stabilì sull'isola come sorvegliante nel 1962 David Wingate, che aveva accompagnato Mowbray e Murphy nella loro spedizione nel 1951, quando era ancora uno studente. Uccelli tropicali più grandi dei cahow usurpavano i loro nidi per deporvi le uova, scacciandone i piccoli appena nati, cosicché Wingate e Mowbray escogitarono una serie di protezioni in legno che impedissero agli uccelli tropicali più grossi di entrare nei nidi. Nel 1966 il totale delle coppie di cahow che si riproducevano era aumentato a 24, per salire ulteriormente a 40 e più negli anni novanta. Negli anni sessanta furono identificati in uova di cahow che non si erano schiuse e in piccoli morti alti livelli di insetticidi come il DDT: l'uso di questo insetticida fu presumibilmente la causa del declino osservato nella popolazione dei cahow nei primi decenni dopo la riscoperta della specie. Fra la fine degli anni '60 e l'inizio degli anni settanta, mentre l'uso del DDT andava declinando nel Nordamerica, il successo riproduttivo dei cahow riprese a salire verso i tassi precedenti. All'inizio del 1987 una civetta delle nevi (Bubo scandiaca) venne a trovarsi in qualche modo fra i cahow sulla Nonsuch Island, e uccise almeno cinque uccelli che non si erano ancora riprodotti. Poi si abbatté sull'isola una calamità naturale ancora maggiore: nel 1989 l'uragano Hugo causò una mortalità insolitamente elevata nella popolazione dei piccoli petrelli, e nel 1990 ci fu una riduzione consistente del numero delle coppie che si impegnarono nella riproduzione. I cahow sono ben adattati a sopravvivere ai normali uragani, purché le tempeste rimangano sull'oceano. Quando però uragani molto potenti si muovono verso il continente americano, i cahow possono restare intrappolati contro la costa ed essere poi trasportati nell'interno dal forte vento, per essere poi abbandonati in regioni coperte da foreste o ritrovarsi perduti su laghi interni. Non solo i cahow furono colpiti duramente da uragani sul golfo del Messico, dove si procuravano il loro cibo, ma il 21 settembre le isolette su cui si riproducevano nelle Bermuda furono devastate dall'uragano Gert.

Situazione attuale

Oggi, grazie ai programmi attivi di conservazione, sopravvivono circa 125 coppie di cahow in età riproduttiva; ognuna di queste procrea e alleva il proprio figlio unico, che trascorrerà poi i primi otto anni di vita sull'oceano aperto prima di tornare da adulto a riprodursi a sua volta e completare il ciclo. Dopo la sua prima visita a Nonsuch nel 1951, il naturalista delle Bermuda David Wingate ha salvato quasi da solo dall'estinzione la specie dei cahow, che erano sospesi in un precario equilibrio. Attraverso i suoi sforzi, il Cahow Conservation Program è diventato uno dei programmi di recupero di specie a rischio di estinzione di maggior successo sull'intero pianeta. Wingate, che è oggi presidente della Bermuda Audubon, oltre che Conservation Officer dei Parchi delle Bermuda, prevede che per il 2020 su Nonsuch Island e su isolette vicine ci saranno un migliaio di coppie di cahow.

Note

De bermudastormvogel (Pterodroma cahow) is een tot de stormvogels en pijlstormvogels behorende vogel. Het is een bedreigde, endemische zeevogelsoort van de Bermuda-eilanden.

Kenmerken

De vogel is 38 cm lang. Het is een middelgrote stormvogel met relatief lange vleugels. De vogel is overwegend bruingrijs en wit. De vogel is boven op de kop bruinzwart; deze kopkap reikt bijna tot het oog. Verder een bruine vlek op de nek die iets naar benenden uitloopt tot op de borst. Van boven is de vogel verder bruinachtig grijs, soms met een lichtgekleurde eindband op de bovenstaart. Van onder is de vogel wit, met een smalle donkere banden aan de voor- en achterkant van de ondervleugel. De snavel is zwart en de poten zijn roze.^[1]

Verspreiding, leefgebied en foerageergedrag

Mogelijk was de vogel talrijk voor Spaanse en Engelse zeevaarders in 1621 de eilanden in bezit namen en een slachting aanrichtten. Eeuwen daarna werd de zeevogel niet opgemerkt en pas in 1916 werd de vogel voor de wetenschap beschreven. Het holotype was een opgezet exemplaar dat in 1906 was verzameld.^[2] De vogel was toen al een zelden opgemerkte bijzonderheid. In 1951 werd ontdekt dat de zeevogels broedden op een klein rotseiland dat behoort tot de gemeente Sant George in het oostelijk deel van Bermuda. Oorspronkelijk broedden de vogels in nestholen in de grond. De laatste overlevenden broedden in rotsspleten van kalksteenkliffen en nu broeden zij in door mensen gemaakte broedholen in natuurreservaten. Buiten de broedtijd verblijven de vogels op volle zee en verspreiden zich over een groot deel van de Atlantische Oceaan waar ze tot aan de Azoren en in het Caraïbisch gebied worden waargenomen.Hij leeft van onder andere van inktvissen, ansjovis en krill.^[1]

Status

In het begin van de 16e eeuw werden de Bermuda-eilanden ontdekt door Spanjaarden. Er leefden toen tienduizenden bermudastormvogels op de eilanden in het oosten. De Spaanse zeelui, die vaak erg bijgelovig waren, waren doodsbang voor de geluiden die de vogels 's nachts maakten, en vertrokken weer van het eiland. Doordat de Spanjaarden enkele varkens op het eiland achterlieten kwamen de nestholen in de bodem in gevaar. De wroetende varkens aten de eieren en jongen van de vogels op, waardoor in 1609, toen de Engelsen zich op het eiland vestigden, de vogels alleen nog maar op enkele kleine, afgelegen rotseilanden voorkwamen. De Engelsen namen echter honden, katten en ratten mee, waardoor de vogelsoort nog meer in gevaar kwam; zeker omdat de Engelsen zelf ook wel vogels aten. Rond 1620 leek de soort bijna uitgeroeid.^[3]

Meer dan drie eeuwen later, in 1951, werden echter toch enkele broedende vogelparen op rotsachtige eilanden die behoren tot de gemeente Sant George gevonden. Een van de eilanden is Nonsuch Island, wat een natuurreservaat werd. Het is opgeschoond van de ratten en tussen 2004 en 2008 werden er meer dan 100 grote kuikens van kleinere rotseilanden gezet. Volwassen vogels zochten het eiland later weer op om er te gaan broeden in kunstmatig aangebrachte nestholen.^[1]

De grootte van de populatie werd in 2016 door BirdLife International geschat op 250 individuen, waaronder minimaal 142 broedparen. De populatie-aantallen nemen sindsdien toe. De vogelstand is echter afhankelijk van beschermingsmaatregelen en voortdurend beheer. Als echter de aantallen blijven stijgen kan de huidige status van bedreigd worden omgezet in kwetsbaar op de Rode Lijst van de IUCN.^[1]

Bermudapetrell (Pterodroma cahow) er ein pelagisk sjøfugl i stormfuglfamilien, ein mellomstor petrell som hekkar utelukkande på Bermuda. Dette er nasjonalfuglen for Bermuda, og eit symbol på von for naturvern. Bermudapetrellen var trudd å vere utrydda i 330 år, og blei gjenoppdaginga som ein Lazarus-art, det vil seie ein art funnen igjen etter å ha vore vurdert som utdøydd i århundre. På Bermuda er han kjent som 'cahow', eit lydhermande namn avleidd frå det uhyggelege skriket som denne fuglen læt.

Skildring

Bermudapetrellen er ca. 38 centimeter i kroppslengd, oversida er gråbrun, undersida kvit. Nebbet er svart og beina rosa. Vengene er lange, med vengespenn på 89 cm.^[1] Den mørke hetta går ned under auget og ein trekantspiss frå nakken ned mot halsen dannar ein ufullstendig brun krage. Langs den kvite undervengen har han ein smal, svart bakkant, vengespissane er òg svarte med eit smalt band i framkanten av vengen inn mot kroppssida.

Som andre medlemmer av stormfuglfamilien, lever bermudapetrellen ute på opent hav og i ein alder av fem år flyg han første gongen tilbake til fødeplassen for å hekke. Dei dannar livslange parsamband. Paret har eit kull i sesongen og hoa legg berre eit egg per kull, reproduksjonsraten er derfor låg. Opphavleg hekka denne arten rikeleg og spreidd over heile øygruppa Bermuda, i dag berre på holmar i Castle Harbour og på Nonsuch Island som er under tilsyn og tilrettelegging for hekking. Når dei ikkje hekkar trur ein dei beitar i Atlanteren, og følgjer nordover den varme delen av den vestlege kanten av Golfstraumen.^[2]

Populasjonen vart nesten utsletta etter at engelske kolonistar innførte rotter, kattar og hundar på Bermuda, og ein trudde fuglane vart drivne til utrydding ca. 1620.

I 1951 vart 18 overlevande hekkande par funne på ein holme i Castle Harbour,^[3] og eit program for vern og restaurering av hekkelokalitetar vart sette i verk.^[4]

Arten har status som sterkt truga, og bestanden er estimert til 250 individ, minst 142 av dei kjønnsmodne (2005), og bestanden er aukande.^[2]

Kjelder

Referansar

Petrel bermudzki (Pterodroma cahow) – gatunek średniego ptaka z rodziny burzykowatych. Endemiczny dla Bermudów.

Przez ponad 300 lat uważano, że wymarł, ale w roku 1935 został ponownie odkryty. Obecnie cała populacja to około 140 osobników^[3]. Na wyspie Nonsuch, dzięki programowi stale monitorującemu sukces lęgowy, jego liczebność wzrasta.

Mierzy 38 cm, waży 250 g. Z wierzchu jest szarobrązowy z ciemniejszą głową, spód ma biały, kuper jasny. Jest wędrowny. Przez większość roku przebywana otwartym morzu, w okresie lęgowym przebywa na wyspach; lęgi odbywa w norach.

Przypisy

Bibliografia

• David Burni, Ben Hoare, Joseph DiCostanzo, BirdLife International (mapy wyst.), Phil Benstead i inni: Ptaki. Encyklopedia. Warszawa: Wydawnictwo Naukowe PWN, 2009, s. 149. ISBN 978-83-01-15733-3.

Bermudapetrell^[2] (Pterodroma cahow) är en hotad fågel i familjen liror inom ordningen stormfåglar.^[3]

Utseende

Bermudapetrellen är en medelstor och långvingad brungrå och vit petrell med en längd på 38 centimeter. Den har en brunsvart hätta som går ner till ögat, avbruten av ett blekt ögonbrynsstreck. Den bruna nacken sträcker sig framåt mot övre delen av bröstet och formar på så sätt delvis ett halvband. Mantel, övre delen av vingarna och stjärten är brungrå. Övre stjärttäckarna är blekare och kan uppfattas som ett smalt vitt band.

Undersidan är helvit, liksom undersidan av vingarna, bortsett från svart spets och svart bakkant. Näbben är svart, benen rosa. Liknande karibpetrellen (P. hasitata) är större, har vit nacke och tydligare vit övergump, men de kan ändå vara svår att skilja åt till havs.

Utbredning

Fågeln häckar på Nonsuch Island utanför Bermuda och tillbringar adulttiden över öppet hav längs Golfströmmen.^[3] Den ses regelbundet utanför USA:s östra kust. Vid två tillfällen har arten med säkerhet påträffats i Europa, dels en återkommande individ 2002-2006 vid Ilhéu da Vila, Santa Maria i Azorerna, dels ett exemplar utanför Irlands västkust 19 maj 2014.^[4] Den har även påträffats i Bahamas och i Kanada.^[1]

Ekologi

Tidigare häckade fågeln likt sina släktingar i utgrävda bohålor, men eftersom miljö som gör utgrävning möjlig inte finns tillgänglig idag häckar den istället i klippskrevor och artificiella bohålor. Den häckar från januari till juni, med en kraftigt ökande häckningsframgång från färre än 5% under 1950-talet till mer än 25% under 1990-talet. Ringmärkning visar att fåglar återvänder för att häcka först fyra år efter att de kläckts. Mellan mitten av juni och mitten av oktober förekommer inga fåglar i häckningsområdet.^[1]

Nykläckt bermudapetrell.

Status och hot

Bermudapetrellen häckade förut i mycket stora antal på Bermuda, men ansågs vara utdöd i nästan tre sekel innan enstaka individer återigen började rapporteras i början av 1900-talet. 1951 hittades en häckningskoloni med 18 par. Idag uppskattas beståndet till 250 individer och man tror att fågeln kommer öka i antal i framtiden. Om detta blir fallet kommer arten troligtvis att placeras i en lägre hotkategori än starkt hotad där internationella naturvårdsunionen IUCN placerar den idag.^[1]

Namn

Fågelns vetenskapliga artnamn cahow är vad bosättare som kom till Bermuda på 1600-talet kallade fågeln, efter dess läte.^[5]

Noter

1. ^ [a b c d] Birdlife International 2012 Pterodroma cahow Från: IUCN 2015. IUCN Red List of Threatened Species. Version 2015.4 www.iucnredlist.org. Läst 2016-02-01.
2. ^ Sveriges ornitologiska förening (2017) Officiella listan över svenska namn på världens fågelarter, läst 2017-08-14
3. ^ [a b] Clements, J. F., T. S. Schulenberg, M. J. Iliff, D. Roberson, T. A. Fredericks, B. L. Sullivan, and C. L. Wood (2015) The eBird/Clements checklist of birds of the world: Version 2015 http://www.birds.cornell.edu/clementschecklist/download, läst 2016-02-11
4. ^ Tarsiger.com Fynd av bermudapetrell i Västpalearktis
5. ^ Jobling, J. A. (2016). Key to Scientific Names in Ornithology. Ur del Hoyo, J., Elliott, A., Sargatal, J., Christie, D.A. & de Juana, E. (red.) (2016). Handbook of the Birds of the World Alive. Lynx Edicions, Barcelona. Hämtad från www.hbw.com.

Externa länkar

• Wikimedia Commons har media som rör bermudapetrell.
  Bilder & media
• Wikispecies har information om Pterodroma cahow.
  Artförteckning
• Bilder och filmer på Internet Bird Collection
• Läten på xeno-canto.org

• 1 Опис
• 2 Поширення
• 3 Історія
• 4 Джерела

Pterodroma cahow (tên tiếng Anh: "Bermuda petrel" - hải âu Bermuda) là một loài hải âu thuộc chi Pterodroma. Thường được gọi là cahow tại Bermuda, một cái tên xuất phát từ tiếng kêu của nó, đây là quốc điểu của Bermuda và xuất hiện trên tiền tệ Bermuda. Đây là một loài chim biển hiếm. Chúng có kích thước trung bình với đôi cánh dài.

Chú thích

Tham khảo

Bài viết liên quan đến chim này vẫn còn sơ khai. Bạn có thể giúp Wikipedia bằng cách mở rộng nội dung để bài được hoàn chỉnh hơn.

• x
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Pterodroma cahow
(Nichols & Mowbray, 1916)

Вымирающие виды
IUCN 3.1 Endangered: 22698088

Бермудский тайфунник^[1] (лат. Pterodroma cahow) — один из немногих видов отряда буревестникообразных, который обитает не на территории Тихого океана. Эта ночная гнездящаяся на земле морская птица — национальная птица Бермудских островов, а также символ надежды на защиту природы. Его драматическое «переоткрытие» (Эффект Лазаря), то есть открытие вида после того, как он считался вымершим столетия, вдохновило документалистов.

Первоначально распространённые по всему архипелагу, бермудские тайфунники являются медленно размножающимися птицами, но в то же время отличными летунами, и поэтому проводят свою взрослую жизнь в открытых морях. В 5 лет птица возвращается на своё бывшее место гнездования для воспроизводства, откладывая только одно яйцо за сезон.

Зловещие ночные крики бермудских тайфунников остановили первых испанских мореплавателей от основания поселений на островах из-за их суеверий, так как они считали, что эти острова были населены демонами. Вместо этого первопроходцы стали разводить свиней на прибрежных участках, тем самым начав стремительную атаку на существование птиц. Последующая колонизация Бермудских островов англичанами привела к тому, что появились такие виды, как крысы, кошки и собаки, и массовые истребления птиц первыми колонистами сократило численность в десятки раз. С 1621 года птицы считались истреблёнными.

В 1951 году на группе скалистых островов Касл Харбор было обнаружено 17 гнёзд, и Дэвидом Вингейтом (англ.) была начата программа по построению бетонных нор и деревянных перегородок для гнездовых туннелей для того, чтобы держать в стороне немного более крупного естественного врага белохвостого фаэтона, и по восстановлению близлежащих к острову Нонсач островов, формируя на них будущую жизнеспособную основу для видов.

Находясь под защитой закона, популяция начала хорошо восстанавливаться. Главная угроза для их будущего — это отсутствие подходящего ареала для размножения. Ураган Фабиан (англ.) уничтожил многие гнездовые норы в 2003 году. Недавно более крупный по размерам и экологически восстановленный остров Нонсач (англ.) был вновь заселён птенцами, их перемещение было удачно запланировано, так они оставят свой след на этих окрестностях. Эта работа ведётся под контролем текущего офицера по охране природы Бермудских островов Джереми Мадейроса, которому содействует австралийский специалист по буревестникам Ник Карлайл.

Однако общая популяция этих птиц на 2005 год составила всего лишь около 250 особей.

Примечания

百慕達海燕（學名：Pterodroma cahow、英语：Bermuda Petrel）是一種虻圆尾鸌（Gadfly petrel），在百慕達因其怪異的叫聲而被稱為Cahow。百慕達海燕為夜行性、在地上築巢的海鳥，是百慕達的國鳥^[2]，也是自然保育希望的象徵之一，因為牠本來被認為在330年前就已絕種，但後來被重新發現並被歸入拉撒路物种（Lazarus taxon），即消失幾世紀後又出現在地球上的物種。是許多記錄片的拍攝對象。

繁殖

百慕達海燕原本在百慕達群島數量很多。這種鳥繁殖很慢，但擅長飛行，其成鳥期幾乎都在海上飛行。五歲時會回到其出生地並開始繁殖，只產下一顆卵，其婚配制度為終生婚配。

歷史與保育

因百慕達海燕為夜行性，牠們詭異的叫聲曾嚇阻迷信的西班牙航海家，認為該島上有惡魔居住。他們雖然不敢在島上長居，卻開始以百慕達海燕為來往船隻的食物補給，開始了對百慕達海燕的屠殺。在百慕達成為英國殖民地後，殖民者引進的外來種如鼠、貓、狗，加上殖民者本身的獵殺大幅減少了這種鳥的數量。雖然百慕達海燕被世界最早的自然保護法：百慕達總督公告的「against the spoyle and havocke of the Cohowes」保護，在1620年時這種鳥已近乎滅絕。

二十世紀初期，科學家陸續採集到一些這種鳥的樣本，顯示百慕達海燕尚未滅絕^[2]。1951年，美國鳥類學家罗伯特・墨菲（Robert Cushman Murphy）與路易斯・莫布雷（Louis L. Mowbray）在百慕達群島的城堡灣（Castle Harbour）的小島發現了18對巢中成對的百慕達海燕^[2]，當時隨船的還有15歲的小男孩David B. Wingate，他在之後的生涯中致力於百慕達海燕的復育，並在1966年成為百慕達的第一位保育官員。Wingate建立了一項計畫，在島上建了許多人工洞穴做為其巢的通道，同時可避免體型稍大的白尾熱帶鳥競爭。並保留鄰近的楠薩奇島為未來可行的復育基地^[3]。

在自然保育之下，百慕達海燕的數量開始增加，目前最主要的困難是缺乏適合的繁殖地點，2003年的費邊颶風（Hurricane Fabian）即摧毀了許多繁殖洞穴。截至2012年，已有81隻幼鳥被移至較大且未開發的楠薩奇島（在幼鳥時就遷移是為了使其對周圍環境產生印痕），這項工作由現任百慕達保育官員Jeremy Madeiros負責執行，並有澳洲海燕專家Nick Carlile的協助^[4]。

2005年，全球的百慕達海燕總數仍只有約250隻^[4]。

參考資料

バミューダミズナギドリ（Pterodroma cahow）は、ミズナギドリ目ミズナギドリ科に分類される鳥類。別名バミューダシロハラミズナギドリ。

分布[編集]

イギリス（バミューダ諸島）固有種

形態[編集]

全長35-36cm。翼開張89cm。上面は灰褐色、下面は白い羽毛で被われる。頭部は黒い羽毛で被われるが、額や眼先は白い。風切羽の色彩は暗褐色。

虹彩は暗褐色。嘴の色彩は黒い。後肢の色彩はピンク色。

生態[編集]

海洋に生息する。

食性は動物食で、魚類、甲殻類、軟体動物を食べると考えられている。

傾斜が緩やかな森林や海岸の斜面に空いた穴に、1月に1回に1個の卵を産む。雌雄交代で抱卵し、抱卵期間は51-54日。

人間との関係[編集]

以前は食用とされていた。

開発による生息地の破壊、食用の乱獲、人為的に移入されたブタやネズミによる卵や雛の捕食、農薬による繁殖率の低下、シラオネッタイチョウとの競合などにより生息数は激減した。以前は絶滅したと考えられていたが、1951年に18ペアが再発見された。1621年には捕獲が禁止されている。外敵の駆除、巣穴の入り口を木板で狭める事により地面に空いた穴で本種のみ営巣できるようにするなどの対策が進められ、わずかだが生息数は増加傾向にある。1993-1994年における生息数は営巣したペアが44-45、巣立った雛が21羽確認されている。

関連項目[編集]

• ミズナギドリ科

参考文献[編集]

• 小原秀雄・浦本昌紀・太田英利・松井正文編著 『動物世界遺産 レッド・データ・アニマルズ1 ユーラシア、北アメリカ』、講談社、2000年、178-179頁。
• 黒田長久監修 C.M.ペリンズ、A.L.A.ミドルトン編 『動物大百科7 鳥I』、平凡社、1986年、53、55、57、70頁。

外部リンク[編集]

• IUCN Red List - Home Page -
  • BirdLife International 2008. Pterodroma cahow. In: IUCN 2009. IUCN Red List of Threatened Species. Version 2009.1.