Wikipedia

Guam rail

Wikispecieshas information related toGallirallus owstoni.

TheGuam rail(Hypotaenidia owstoni), known locally and inChamorroasko'ko',is a small, terrestrialbirdendemic to Guam in theRallidae family.[2][3]They are one of the island's few remainingendemicbird species. The species becameextinct in the wildin the early 1980s when biologists captured the remaining wild population to establish a breeding program. They have since been successfully introduced to the nearbyRotaandCocosislands.[4]In 2019, they became the second bird species to be reclassified by theInternational Union for the Conservation of Naturefrom Extinct in the Wild toCritically Endangered.[1][5]

Guam rail
Guam rail at theCincinnati Zoo
Scientific classificationEdit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: Gruiformes
Family: Rallidae
Genus: Hypotaenidia
Species:
H. owstoni
Binomial name
Hypotaenidia owstoni
Synonyms
  • Rallus owstoni(Rothschild, 1895)
  • Gallirallus owstoni(Rothschild, 1895)

Adult male and female plumage is primarily brown with barred black-and-white plumage on their underside. Their heads are brown with a grey stripe running above the eye and a medium-length grey bill. They have strong legs with long toes that help them walk over marshy ground.[6]Their most common vocalizations are short "kip" notes, but also screeches during the breeding season.[7]

Guam rail numbers fell drastically due to predation by invasivebrown treesnakes.[4]The species is now being bred in captivity by the Division of Aquatic and Wildlife Resources on Guam, and at some mainland U.S.zoos.Since 1995, more than 100 rails have been introduced on the island ofRotain theCommonwealth of the Northern Mariana Islands,in an attempt to establish a wild breeding colony. In 2010, 16 birds were released ontoCocos Island,with 12 more being introduced in 2012.[1]

Taxonomy and etymology

edit

The Guam rail was first described asHypotaenidia owstoniin 1895 by LordWalter Rothschild.Rothschild announced thespecific nameowstoniwas "in honour of Mr.Alan Owston,of Yokohama, whose men have collected for me on theMarianne Islands."[8]The generic name,Hypotaenidia,comes from the Ancient Greekhypomeaning "under" andtainiameaning "stripe" or "band."[9][10]This refers to the banded feathers seen on their underside and wings, typically found across rail species.[11]

Hypotaenidia
Cladogram of the genus Hypotaenidia[12]

Description

edit

Guam rails are a medium-sizedrailspecies, growing to about 11 inches (28 cm) in total length. Adults will weigh around 7 to 12 ounces (200 to 350 grams).[6]They have an elongated body, with small wings and medium-length legs. Guam rails have underdeveloped wing muscles and are consideredflightless,though they can fly about 3 to 10 feet (1 to 3 meters) at once. Their strong leg muscles make them fast runners instead.[13]

Adult Guam rails aremonomorphic,meaning males and females have the sameplumageand characteristics. They are primarily brown, with a grey bill and tan-colored legs. The head and back are brown. It has a grey eye stripe and throat, a dark blackish breast with white barring, and the legs and beak are dark brown.[5]

Distribution and habitat

edit

Historically, the rail was only found on the island of Guam. Today, the rail is still found on Guam, though in captivity, with wild populations introduced on Rota and Cocos Islands. Since 1985, the rails have only lived in captivity on Guam, located at the Guam Department of Agriculture.[14]Guam is an island covering about 132,230 acres. According to a 2013 survey, about 53% of the island is forested. The climate istropical marine,with little change in temperature throughout the year and a dry season lasting from January until May.[citation needed]

The rails were once distributed widely across most habitats on the island, including mixed forest, savanna, grasslands, fern thickets, and agricultural areas. Individuals observed by the Guam Division of Aquatic and Wildlife Resources were noted as preferring edge habitats that provided good cover.[15]

Ecology and behavior

edit

Guam rails are secretive, fast birds. Though they are capable of a short bursts of flight, they seldom fly. It was found more frequently in savannas and scrubby mixed forest than in uniform tracts of mature forest. It was usually found in dense vegetation but it was also observed bathing or feeding along roadsides or forest edges.[16]Its call is a loud, piercing whistle or series of whistles, usually given by two or more birds in response to a loud noise, the call of another rail, or other disturbances. Though individuals will respond almost invariably to the call of another rail, the species is generally silent.

Breeding

edit

It is a year-round ground nester and lays 2–4 eggs per clutch, and both parents share in the construction of a shallow nest of leaves and grass. They mature at six months of age, and have been known to produce up to 10 clutches per year in captivity.

Their nesting habits make them highly susceptible to predators, such as the nativeMariana monitorand the invasiveferal pig,feral cat,feral dog,mangrove monitor,brown tree snake,black rat,andNorway rat.

Food and feeding

edit

Guam rails areomnivorousforagers known to consumegastropods,insects,geckos,seeds, and vegetable matter.[6]A large part of their diet consists ofgiant African snails,which were introduced to Guam around 1945 and became a easy food source for the birds. Pieces ofsnail shellandcoralhave been found in the stomach andgizzardcontents of Guam rails, suggesting use as grit.[17]

Guam rails have been observed foraging and hunting. When foraging, they peck food from the ground and eat seeds and flowers from grasses. They have also been observed hunting insects, particularly butterflies.[17]

Parasites

edit

The species hosted a unique louse,Rallicola guami,[18]which seems to have been a victim ofconservation-induced extinction,since Guam rails taken into captivity were deloused to assist survival; it is considered most likelyextinct.[19]

Threats

edit
A brown treesnake on a barbed wire fence.

Thebrown treesnake(Boiga irregularis) is one of the primary threats to the survival of the Guam rail; the introduction of the snake has been catastrophic for Guam's biodiversity. The snake was likely passively introduced to the island as a stowaway in a military cargo ship after World War II. Once introduced to Guam, it thrived with an abundance of prey lacking natural predators.[20]The snake is anopportunistic feeder,and on Guam has been observed to consume lizards, birds, eggs, insects, small mammals, and human trash. The snake is nocturnal and arboreal and adept at preying on roosting and nesting birds and their offspring. Over time, the snake decimated the populations of other nativeavifaunain Guam's forests. With less prey found in the trees, it took advantage of the nests of the Guam rail, found on the forest floor.[21]It is unlikely the snakes could prey on the larger adult rails, instead feeding on the eggs and nestlings.[22]

Invasive ungulates, includingferal pigsandPhillippine deer,destroy native forests and consequently, Guam rail habitat. Their behaviors contribute to the decline of Guam's forests by trampling vegetation and rooting for food. In addition to this, feral pigswallowingand deer thinning the forest canopy contribute to the ecosystem's disruption. These factors combined have contributed to altered soil properties, forest ecology, and decreases in groundcover.[23]

Feral cats have also proven to be a major barrier to successfully reintroducing the species to Guam. Following the reintroduction of Guam rails atAndersen Air Force Basein 2006, feral cats killed all of the introduced birds within eight weeks.[24][25]

Conservation

edit
Ceremonial statue of a Guam rail (ko'ko), presented as a gift by the Government of Guam

Decline

edit

The species was once abundant, with an estimated population between 60,000 and 80,000 in the late 1960s and early 1970s.[14]Nine of the eleven species of native forest-dwelling birds have been extirpated from Guam. Five of these were endemic at the species or subspecies level, and are now extinct. The Guam rail and theGuam kingfisher,are bred in captivity with hope that they may eventually be released back into the wild. Several other native species exist in precariously small numbers, and their future on Guam is perilous. Most native forest species, including the Guam rail, were virtually extinct when they were listed as threatened or endangered by theU.S. Fish and Wildlife Servicein 1984.

Appreciable losses of the Guam rail was not evident until the mid 1960s. By 1963, several formerly abundant rails had disappeared from the central part of the island where snakes were most populous. By the late 1960s, it had begun to decline in the central and southern parts of the island, and remained abundant only in isolated patches of forest on the northern end of the island. Snakes began affecting the rail in the north-central and extreme northern parts of the island in the 1970s and 1980s, respectively. The population declined severely from 1969 to 1973, and continued to decline until the mid 1980s. It was last seen in the wild in 1987.[citation needed]

Conservation efforts

edit

ZoologistBob Beck,a wildlife supervisor with theGuam Department of Agriculture's Division of Aquatic and Wildlife Resources, is credited with leading the efforts to capture the remaining wild Guam rails, Guam kingfishers, and other native birds to save them from extinction. His efforts to save the Guam rail began in 1982, and lasted more than 20 years. Beck was considered to be instrumental in capturing the remaining population of Guam rails, and establishingcaptive breedingprograms for the species on Guam. He later established a release site and an introduced breeding population of Guam rails on the neighboring island ofRotain theNorthern Mariana Islands.[26]

Beck was also a driving force in establishing Guam rail breeding programs inzoosthroughout the mainlandUnited States.Beck's Guam rail breeding program initially began with just three zoos in the U.S.—theBronx Zoo,thePhiladelphia Zoo,and theNational Zoo in Washington, D.C.The program proved to be successful, and was soon expanded to include other zoos. As of 2008, seventeen zoos now participate in the Guam rail breeding program, including: theAudubon ZooinNew Orleans,theSan Diego Zoo,theSanta Fe College Teaching Zoo,and zoos inChicago,Houston,andSan Antonio.[26]

The efforts by Beck, and others, to save the Guam rail have been promising. There are now approximately 120 Guam rails incaptivityin Guam, and approximately 35 birds in captive breeding programs throughout the United States. Biologist Gary Wiles, who worked on the Guam rail breeding program from 1981 through 2000, said of Beck's efforts to save the Guam rail, "Bob was one of the first to begin organizing catching the birds, so they could be brought into captivity, held there, and bred. He started a captive population. We still have Guam rails today because of his efforts." Suzanne Medina, a wildlife biologist, also credited Beck with saving the Guam rail, "Bob Beck was the ko'ko' champion; [he] was Guam's champion at the time for preventing the extinction of these birds."[26]

A recent effort to introduce rails on Guam in a 22hectareforested area concentrated on protecting the rails by limiting snakes using a combination of trapping and a perimeter barrier to reduce re-invasion by snakes. This endeavor allowed the tentative survival of several pairs of rails released into the area. Reproduction by the rails was reported in this control area on the basis of sounds attributed to chicks. The preliminary success constitutes one of the few bright spots in the conservation of Guam's native fauna in recent years, and speaks to future opportunities to recover wildlife.[27]

In November 2010, sixteen Guam rails were released onCocos Island,a 33 hectareatolllocated 1 mile off the southern tip of Guam, as part of its reintroduction two decades after its extinction in the wild. It was an effort to provide safe nesting areas for the rails, as well as a place for the public to see them in the wild.[citation needed]Before the reintroduction, rats were eradicated off the island, and the forest was further enhanced with native trees. A native lizard survey was conducted to make sure that the rails had enough food to eat. Monitor lizard populations were reduced to minimize their impacts on the newly released rails. The reintroduction proved to be successful, as evidence of breeding has been observed. This will provide a model environment to develop strategies for future reintroductions, as well as expertise in rodent and snake detection, eradication, andbio-securitymeasures.[28]

In culture

edit

Guam's symbolic bird is the Ko'ko'.[29]

Ko'ko' Road Race Weekend is hosted every year on Guam to raise awareness of the species and conservation efforts.[30]

See also

edit

References

edit
  1. ^abcBirdLife International (2019)."Hypotaenidia owstoni".IUCN Red List of Threatened Species.2019:e.T22692441A156506469.doi:10.2305/IUCN.UK.2019-3.RLTS.T22692441A156506469.en.Retrieved19 November2021.
  2. ^Hurrell, Shaun (20 January 2020)."How did the Guam Rail come back from extinction in the wild?".Birdlife.org.Retrieved2 April2020.
  3. ^"Guam Rail - Guampedia".guampedia.2009-09-30.Retrieved2024-08-18.
  4. ^ab"Conserving the Last of Guam's Avifauna: The Recovery of the Guam Rail".Smithsonian's National Zoo and Conservation Biology Institute.2020-01-13.Retrieved2024-08-17.
  5. ^abSarah Lazarus (19 December 2019)."For the second time in history, a bird has been brought back from extinction in the wild".CNN.Retrieved2019-12-22.
  6. ^abc"Guam rail (ko'ko')".Smithsonian's National Zoo and Conservation Biology Institute.Retrieved2024-08-17.
  7. ^"Guam Rail - eBird".ebird.org.Retrieved2024-08-18.
  8. ^Rothschild, Lionel Walter (1895)."A New Species of Rail".Novitates Zoologicae.2:480.
  9. ^"Definition of HYPO".merriam-webster.Retrieved2024-08-19.
  10. ^Brown, Roland W. (Roland Wilbur) (1954).Composition of scientific words; a manual of methods and a lexicon of materials for the practice of logotechnics.University of Connecticut Libraries. [Washington] 1954.
  11. ^"Rail | Wetlands, Marshlands & Estuaries | Britannica".britannica.Retrieved2024-09-07.
  12. ^del Hoyo, J.; Collar, N. J.HBW and BirdLife International Illustrated Checklist of the Birds of the World.Vol. 1. Barcelona, Spain and Cambridge, UK: Lynx Edicions and BirdLife International.
  13. ^"Guam Rail | San Diego Zoo Animals & Plants".animals.sandiegozoo.org.Retrieved2024-08-18.
  14. ^ab"DAWR Kontra i Kulepbla | DOAG".Retrieved2024-08-19.
  15. ^"Guam rail (Gallirallus owstoni)".ECOS Environmental Conservation Online System.U.S. Fish & Wildlife Service.
  16. ^"Guam rail".Smithsonian's National Zoo.2017-05-19.Retrieved2022-08-03.
  17. ^abJenkins, J. Mark (1979)."Natural History of the Guam Rail".The Condor.81(4): 404–408.
  18. ^Emerson, K. C. (1957, August 4).Proceedings of the Entomological Society of Washington,vol. 59, no. -1, August, 1957 185 soc. 2:... Biodiversity Library. Accessed athttps:// biodiversitylibrary.org/partpdf/63868
  19. ^Rózsa, Lajos; Vas, Zoltán (2014-08-22)."Co-extinct and critically co-endangered species of parasitic lice, and conservation-induced extinction: should lice be reintroduced to their hosts?"(PDF).Oryx.49(1): 107–110.doi:10.1017/s0030605313000628.
  20. ^Colvin, Bruce A.; Fall, Michael W.; Fitzgerald, Lee A.; Loope, Lloyd L. (2005)."Review of brown treesnake problems and control programs".USDA National Wildlife Research Center - Staff Publications:631.
  21. ^"3 - Brown Tree Snake".The Scientific Bases for Preservation of the Mariana Crow.Washington, DC: National Academy Press. 1997.doi:10.17226/5372.ISBN0-309-05581-4.
  22. ^Savidge, Julie A. (1987)."Extinction of an Island Forest Avifauna by an Introduced Snake".Ecology.68(3): 660–668.Bibcode:1987Ecol...68..660S.doi:10.2307/1938471.JSTOR1938471.
  23. ^DRAFT JOINT REGION MARIANAS ANDERSEN AIR FORCE BASE UNGULATE MANAGEMENT PLAN(PDF)(Report). SWCA. July 23, 2012. p. 29.Retrieved2024-09-06.
  24. ^Desjarlais, Orville F. (January 17, 2006)."Guam-based conservation helps save endangered species".Air Force.RetrievedAugust 21,2024.
  25. ^Ko'ko's and Kings: the return of Guam's birds - documentaryonYouTube
  26. ^abc"Guam native bird champion dies".Pacific Daily News.2008-06-06.Retrieved2008-06-08.[dead link]
  27. ^"Extinctions and Loss of Species from Guam: Birds".U.S. Geological Survey. 2 November 2006. Archived fromthe originalon 25 December 2013.Retrieved2 January2017.
  28. ^Thornton, Patrick (13 January 2011)."Endemic Guam Rail reintroduced onto Guam after two decades of extinction in the wild".Rare. Archived fromthe originalon 4 January 2017.Retrieved2 January2017.
  29. ^Van Dop Dejesus, Jessica (n.d.)."Guam".National Geographic Kids.RetrievedAugust 21,2024.
  30. ^"Ko'ko' Road Race Weekend".visitguam.Retrieved2024-08-21.
edit
Retrieved from "https://en.wikipedia.org/w/index.php?title=Guam_rail&oldid=1250559993"