Mariana crow: Difference between revisions

| status_ref = <ref name="IUCNiucn Redstatus 12 November List2021">{{IUCNcite iucn |idauthor=22705959BirdLife International |date=2018 |title=''Corvus kubaryi'' |assessorvolume=BirdLife International2018 |assessor-linkpage=BirdLife Internationale.T22705959A129626293 |versiondoi=201310.2305/IUCN.UK.2018-2.RLTS.T22705959A129626293.en |year=2013 |accessdateaccess-date=2612 November 20132021}}</ref>

| regnumgenus = [[Animal]]iaCorvus

| classisauthority = [[birdAnton Reichenow|AvesReichenow]], 1885

The '''Mariana crow''' ('''''Corvus kubaryi''''') ([[Chamorro language|Chamorro]] name: '''''aga'''åga'') is a [[species]] of the [[Corvidae|crow family]] from the Southtropical Western [[Pacific Ocean|Pacific]]. It is a glossy black bird about {{convert|15|in|cm|sp=us}} long and known only from the islands of [[Guam]] and [[Rota (island)|Rota]].

It is a rare bird which has steadily declined in numbers since the 1960s.<ref name=fws>{{cite web |publisher=[[U.S. Fish and Wildlife Service]] (USFWS) |date=20 September 2012 |title=Threatened and Endangered Animals in the Pacific Islands |url=http://www.fws.gov/pacificislands/fauna/marianacrow.html |access-date=17 December 2015}}</ref> On Guam there are believedno toremaining benative very few remainingMariana birdsCrows, the population having been muchdecimated reduced sinceby the introduction of the [[brown tree snake]].<ref>{{Cite report |url=https://www.federalregister.gov/documents/2006/01/11/E6-143/draft-revised-recovery-plan-for-the-aga-or-mariana-crow-corvus-kubaryi |title=Draft Revised Recovery Plan for the Aga or Mariana Crow (Corvus kubaryi) |date=2005 |publisher=U.S. Fish and Wildlife Service |location=Portland, Oregon |access-date=Feb 1, 2023}}</ref> On Rota the population has alsodeclined beento dwindlingfewer than 200 individuals,<ref>{{Cite journal |last1=Kroner |first1=Andria |last2=Ha |first2=Renee Robinette |date=September 2018 |title=An update of the breeding population status of the critically endangered Mariana Crow Corvus kubaryi on Rota, Northern Mariana Islands 2013–2014 |url=https://www.cambridge.org/core/product/identifier/S0959270917000053/type/journal_article |journal=Bird Conservation International |language=en |volume=28 |issue=3 |pages=416–422 |doi=10.1017/S0959270917000053 |s2cid=90635351 |issn=0959-2709}}</ref> the main threats here being the reduction of suitable habitat because of development and predation. SomeDespite translocations from Rota to the [[Guam National Wildlife Refuge]] in the late 1990s and early 2000s, by 2011 the Mariana Crow was extirpated from Guam.<ref>{{Cite journal |last1=Cortes-Rodriguez |first1=Nandadevi |last2=Campana |first2=Michael |last3=Berry |first3=Lainie |last4=Faegre |first4=Sarah |last5=Derrickson |first5=Scott |last6=Ha |first6=Renee |last7=Dikow |first7=Rebecca |last8=Rutz |first8=Christian |last9=Fleischer |first9=Robert |date=2019-03-01 |title=Population Genomics and Structure of the Critically Endangered Mariana Crow (Corvus kubaryi) |journal=Genes |language=en |volume=10 |issue=3 |pages=187 |doi=10.3390/genes10030187 |pmid=30832245 |pmc=6471520 |issn=2073-4425 |doi-access=free }}</ref> Current conservation efforts haveon beenRota undertakeninclude habitat protection,<ref>{{Cite web |title=CNMI DLNR Division of Fish & Wildlife |url=http://www.dfwcnmi.com/wildlife-conservation-areas.php |access-date=2023-02-02 |website=www.dfwcnmi.com}}</ref> and somea birdscaptive haverear-and-release beenprogram.<ref>{{Cite relocatedweb from|date=2018-10-08 Rota|title=Endangered Mariana Crows Return to theIsland newForest [[Guam|url=https://science.sandiegozoo.org/news/endangered-mariana-crows-return-island-forest National|access-date=2023-02-02 |website=San Diego Zoo Wildlife Refuge]].Alliance |language=en}}</ref> The [[International Union for Conservation of Nature]] has rated the bird as being "[[critically endangered]]".

The Mariana crow is a small black [[crow]] with a bluish-black gloss on its tail, and a greenish-black gloss on its back, underparts, head, and wings. In general, females are smaller than males. An adult weighs about {{convert|9|oz|g}} and is about {{convert|15|in|cm|sp=us}} long.<ref name="MarzluffAngell2007">{{cite book |author1=John M. Marzluff |author2=Tony Angell |title=In the Company of Crows and Ravens |url=https://books.google.com/books?id=FrG8pIQ5WJkC |year=2007 |publisher=Yale University Press |isbn=978-0-300-12255-18}}</ref>

The Mariana crow has a variety of [[bird vocalization|vocalizations]], including two locational calls used to maintain contact between pairs, family members and [[flock (birds)|flock]] mates. These locational calls are either a high-pitched series of one to three ''caw'' or ''hi'' sounds, or a series of longer ''caw'' sounds with a nasal ''aaa'' element to the call; the latter call may be used exclusively between mated pairs. Alarm calls are a rapid series of sharp ''caw''s. The birds also make a variety of squalling, guttural sounds, which may be done either quietly or excitedly. These sounds are typically accompanied by activities such as the ripping of leaves or the hammering of branches, and may serve as part of courtship or pair bonding.<ref name="Tomback"/>

Extremely versatile, the Mariana crow is an opportunistic [[omnivore]], feeding on insects[[insect]]s, lizards[[lizard]]s, other birds' eggs[[egg]]s, [[hermit crabscrab]]s, fruits[[fruit]]s, and seeds[[seed]]s.<ref name=fws/>

The Mariana crow begins nesting as early as July and as late as MarchMay.{{citation needed|date=December 2015}} The nest is a large, cupped platform of small sticks, lined with leaf fibers. Clutch size varies from 1- to 4 eggs, and both parents incubate the eggs, brood the chicks, and care for the juveniles even after they fledge.{{citation needed|date=December 2015}} Parental care has been known to range from 5 to 18 months, and juveniles may take as long as 3 years before entering the adult breeding cycle.<ref>{{citationCite report |url=https://www.researchgate.net/publication/268207370 |title=Reproduction and juvenile dispersal of Mariana Crows on Rota 1996-1999 |last1=Morton |first1=John |last2=Plentovich |first2=Sheldon needed|date=December1999 |last3=Sharp |first3=Thomas |access-date=Feb 1, 20152023}}</ref>

On Guam, the Mariana crow's decline is primarily due to predation by the introduced [[brown tree snake]] (''Boiga irregularis''). In spite of protection of nesting-sites by electrical tree barriers, the remaining birds are considered to be reproductively senescent. On Rota, many other threats endanger the crow, including homestead development, resort and golf-course construction, agricultural settlement, nest-predation from introduced rats[[rat]]s, the [[mangroveMariana monitor]] lizard (''Varanus indicustsukamotoi''), [[typhoon]]s, predation from [[feral catscat]]s, disease, and competition with the [[black drongo]] (''Dicrurus macrocercus''). More recently, the brown tree snake has also been detected on Rota, likely leading to serious declines in the Mariana crow population there if the snake population establishes itself. The Mariana crow is also persecuted by residents of both islands who see it as an obstacle to development.<ref name="BLI 2008a">{{cite web |publisher=[[BirdLife International]] (BLI) |date=2008 |url=http://www.birdlife.org/datazone/ebas/index.html?action=SpcHTMDetails.asp&sid=5766&m=0 |title=Mariana crow species factsheet |access-date=23 May 2008}}</ref>

In 1993, a [[Guam National Wildlife Refuge|National Wildlife Refuge]] was established on Guam to preserve the remaining forest, and birds are beingwere translocated from Rota. Biologically controlling the brown tree snake is also being discussed.

Crows were transported from Rota to Guam in 2003 to assist conservation efforts thoughtthough this may have had the unintended side effect of decreasing genetic variation within the species as tests have shown the Rota population is less diverse than the Guam.<ref name="MarzluffAngell2007"/>

Formerly classified as an [[endangered]] species by the [[IUCN]],<ref name="IUCNiucn Redstatus List12 November 2021" /> it was suspected to be rarer than generally assumed. Following the evaluation of its status, this was found to be correct, and it is consequently uplisted to [[critically endangered]] status in 2008 as it is in immediate danger of [[extinct]]ion, numbering so few birds that it could be entirely wiped out by a single catastrophic event such as an epidemic of [[West Nile virus]].<ref name="BLI 2008a"/><ref name="BLI 2008b">{{cite web|publisher=[[BirdLife International]] (BLI) |date=2008 |url=http://www.birdlife.org/action/science/species/global_species_programme/whats_new.html |title=IUCN Redlist status changes |accessdateaccess-date=23 May 2008 |deadurlurl-status=yesdead |archiveurlarchive-url=https://web.archive.org/web/20080914020126/http://www.birdlife.org/action/science/species/global_species_programme/whats_new.html |archivedatearchive-date=14 September 2008 |df= }}</ref>

| first = DianeD. F.

{{DEFAULTSORT[[Category:crow, Corvus|Mariana}} crow]]