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Cocos finch

(Redirected fromCocos Island finch)

TheCocos finch(Pinaroloxias inornata) orCocos Island finch,is the only one of theDarwin's finchesnot native to theGalápagos Islands,and theonly memberof thegenusPinaroloxias.Sometimes classified in the familyEmberizidae,more recent studies have shown it to belongs in thetanagerfamily,Thraupidae.It isendemictoCocos Island,a Pacific island which is approximately 360 miles (580 km) south ofCosta Rica.

Cocos finch
Cocos Finch, female
Cocos Finch, male
Scientific classificationEdit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: Passeriformes
Family: Thraupidae
Genus: Pinaroloxias
Sharpe,1885
Species:
P. inornata
Binomial name
Pinaroloxias inornata
(Gould,1843)

Taxonomy

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The Cocos finch wasformally describedin 1843 by the English ornithologistJohn Gouldunder thebinomial nameCactornis inornatus.[2]The species was moved to a new genusPinaroloxiasbyRichard Bowdler Sharpein 1885.[3]The genus name combines theAncient Greekpinarosmeaning "dirty" or "squalid" withLoxia,a genus introduced byCarl Linnaeusin 1758 for the crossbills. The specific epithetinornataisLatinfor "plain" or "unadorned".[4]The Cocos finch is a member of a group collectively known as Darwin's finches.[5]Although traditionally placed with the buntings andNew World sparrowsin the familyEmberizidae,[6]molecular phylogeneticstudies have shown that Darwin's finches are members of thesubfamilyCoerebinae within the tanager family Thraupidae.[7]The Cocos finch was first categorized to be closer to thewarbler finchcladedue to the similarmorphologyof cousin warbler finches.[8][9]

The Cocos finch shares many morphological similarities to other Darwin's finches despite having been separated from the Galapagos Islands.[10]What is unique, however, of the Cocos finch, is that they display an inter-species variation in feeding habits. The variation in foraging behaviors are hypothesized to be possible byobservational learningfrom other Cocos finches.[10][11]These feeding specializations are independent of any morphological changes, sex and age differences, rather, they are derived from an inter-species variation found within the Cocos finch. Still, despite its variation in feeding patterns, Cocos finches are categorized as one species with no known subspecies.[11]

Description

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The Cocos finch stands at about 12 cm long weighing in at about 12.5 g. The bird has a black decurved pointed bill for eating berries and insects that are its main diet.[10][12][13]They aresexually dimorphicin that the males have almost entirely black, having black feathers from the tail, breast, nape, andcrown.Unlike male finches found on theGalapágosislands, male Cocos finches have black beaks year-round, never changing color.[12][14][13]

Female Cocos finches have a lighter brown complexion compared to males. There is a black splattering of feathers on their breast area down to the flank and rump. The belly of the female Cocos finch is milky white compared to themantleof the bird. The nape and crown area are more noticeably black.[12][15][13]The young are similar, but have yellowbills.

The call of a Cocos finch can be described as a "buzzy" like sound with a high-pitched ending note. The beginning of the call can form a “djirr” sound followed by a high pitched “tiew” sound. Calls can also include a high pitched “phzzzz” sound.[13][12]

Distribution and habitat

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Cocos Island viewed from a helicopter

The Cocos finch is exclusively found in Cocos Island (which takes up a 1,997 km2area), 580 km southeast from Costa Rica.[12][16]Cocos finches are not known to have traveled outside of Cocos Island making its habitat and reproduction range to only be 30 km2of the entire island.[12]The habitat of the Cocos finch is mostly withinHibiscus thickets,closed-canopy forestandwoodland forest.[12][13]

The climate within Cocos Island is described to be a typicalrain forestclimate with high humidity and chances for rainfall. The island has a varied landscape with bodies of lakes, streams, and caves and is home to other species including endemic lizards (only 2 species) and some migratory birds.[16]

Ecology and behavior

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Foraging patterns

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Cocos finches are known to be ageneralist species,although they are also known to specialize in an individual level which can result in different foraging behaviors within individual Cocos finches.[10]This specialized behavior of Cocos finches can be explained through learning foraging patterns through other Cocos finches and can resonate said individual behavior to other Cocos Finches.[10][11]

Breeding

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Cocos finch usually nest throughout the year; however, their breeding season falls usually at around January–February.[16][17]They form a nest using lichen and dry moss as their main material. The standard clutch is two brown-spotted whiteeggs,which are hatched in a roughly sphericalnestbuilt at the end of a tree branch. Eggs are in clutch sizes of about 4–5 with a distinctive pink/light brown spots.[13][14]

Threats

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Cocos finches face invasive mammalian predators, like rats and cats, on the island. Despite these predators, there is no evidence of high predatory pressures on the Cocos finches themselves. Scientists conclude that due to the low predatory pressures on Cocos finches, they have developed this specialized feeding behavior to evolve to a more generalist species.[11][12]

Status

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Cocos Island is a natural reserved island, such that there is limited human interaction with the Cocos finch and other Cocos Island wildlife. While there has been increasing tourism around the island, there is no evidence of highdisturbancerates from these tourists to affect the wildlife in the island including the Cocos finch.[12][18]

Despite having a small distribution, due to thepredationand disturbance rate of Cocos finches being low, along with a steady population rate, theIUCNdeems the Cocos finch to be Least Concern.[19][18]

Currently, there are estimated to be about 6,000-15,000 Cocos finches on Cocos Island.[1][18][19]

References

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  1. ^abBirdLife International (2021)."Pinaroloxias inornata".The IUCN Red List of Threatened Species.e.T22723792A180221867.doi:10.2305/IUCN.UK.2021-3.RLTS.T22723792A180221867.en.S2CID245185398.
  2. ^Gould, John(1844).The Zoology of the Voyage of H.M.S. Sulphur: under the command of Captain Sir Edward Belcher, during the years 1836-42.London: Smith, Elder. p. 42,Plate 25.For the publication date see:Zimmer, John T.(1926).Catalogue of the Edward E. Ayer Ornithological Library.Field Museum of Natural History, Zoology Series. Volume 16, Part 1. Vol. 16. Chicago: Field Museum of Natural History. p. 304..
  3. ^Sharpe, R. Bowdler(1885).Catalogue of the Passeriformes or Perching Birds in the Collection of the British Museum. Fringilliformes Part I.Catalogue of the Birds in the British Museum. Vol. 10. London: Trustees of the British Museum. p. 52.
  4. ^Jobling, James A. (2010).The Helm Dictionary of Scientific Bird Names.London: Christopher Helm. pp. 205, 307.ISBN978-1-4081-2501-4.
  5. ^Sato, A.; Tichy, H.; O'hUigin, C.; Grant, P.R.; Grant, B.R.; Klein, J. (2001)."On the origin of Darwin's Finches".Molecular Biology and Evolution.18(3): 299–311.doi:10.1093/oxfordjournals.molbev.a003806.PMID11230531.
  6. ^Paynter, Raymond A. Jr, ed. (1970).Check-List of Birds of the World.Vol. 13. Cambridge, Massachusetts: Museum of Comparative Zoology. p. 168.
  7. ^Burns, K.J.; Shultz, A.J.; Title, P.O.; Mason, N.A.; Barker, F.K.; Klicka, J.; Lanyon, S.M.; Lovette, I.J. (2014)."Phylogenetics and diversification of tanagers (Passeriformes: Thraupidae), the largest radiation of Neotropical songbirds".Molecular Phylogenetics and Evolution.75:41–77.doi:10.1016/j.ympev.2014.02.006.PMID24583021.
  8. ^Grant, Peter; Grant, B. Rosemary (2002). "Adaptive Radiation of Darwin's Finches".American Scientist.90(2): 130.Bibcode:2002AmSci..90..130G.doi:10.1511/2002.2.130.ISSN0003-0996.
  9. ^Schluter, Dolph (September 1984). "Morphological and Phylogenetic Relations Among the Darwin's Finches".Evolution.38(5): 921–930.doi:10.2307/2408428.JSTOR2408428.PMID28555805.
  10. ^abcdeWerner, T. K.; Sherry, T. W. (1987-08-01)."Behavioral feeding specialization inPinaroloxias inornata,the "Darwin's Finch" of Cocos Island, Costa Rica ".Proceedings of the National Academy of Sciences.84(15): 5506–5510.Bibcode:1987PNAS...84.5506W.doi:10.1073/pnas.84.15.5506.ISSN0027-8424.PMC298888.PMID16593864.
  11. ^abcdSmith, James N. M.; Sweatman, Hugh P. A. (1976). "Feeding habits and morphological variation in Cocos Finches".The Condor.78(2): 244.doi:10.2307/1366860.JSTOR1366860.
  12. ^abcdefghi"Cocos FinchPinaroloxias inornata".Data Zone.Bird Life International.Archivedfrom the original on 2020-10-20.Retrieved2019-12-05.
  13. ^abcdefGrant, Peter R. (March 2002)."Birds, Mammals, & Reptiles of the Galápagos Islands: An Identification Guide. By Andy Swash and, Rob Still; with illustrations by Ian Lewington. New Haven (Connecticut): Yale University Press. $24.95. 168 p; ill.; index of English and scientific names. 2000".The Quarterly Review of Biology.77(1):79–79.doi:10.1086/343641.ISBN0-300-08864-7.ISSN0033-5770.
  14. ^abHudon, Jocelyn (January 1987). "Guide des passereaux granivores. Embérizinés Gilbert C. Armani".The Auk.104(1): 152–153.doi:10.2307/4087255.ISSN0004-8038.JSTOR4087255.
  15. ^"Cocos Island FinchPinaroloxias inornata(Gould, 1843) ".Avibase - The World Bird Database.Retrieved2019-12-04.
  16. ^abc"Cocos Island National Park, Costa Rica",Dictionary of Geotourism,Springer Singapore, 2019-11-11, pp. 91–92,doi:10.1007/978-981-13-2538-0_368,ISBN978-981-13-2537-3,S2CID242743344
  17. ^Raffaele, Herbert A. (September 1990). "A Guide to the Birds of Costa Rica.F. Gary Stiles, Alexander F. Skutch".The Quarterly Review of Biology.65(3): 365–366.doi:10.1086/416883.ISSN0033-5770.
  18. ^abcButchart, Stuart H M; Stattersfield, Alison J; Bennun, Leon A; Shutes, Sue M; Akçakaya, H Resit; Baillie, Jonathan E M; Stuart, Simon N; Hilton-Taylor, Craig; Mace, Georgina M (2004-10-26). Walt V Reid (ed.)."Measuring Global Trends in the Status of Biodiversity: Red List Indices for Birds".PLOS Biology.2(12): e383.doi:10.1371/journal.pbio.0020383.ISSN1545-7885.PMC524254.PMID15510230.
  19. ^abBirds to watch 2: the world list of threatened birds: the official source for birds on the IUCN red list.1996-10-01. pp. 34–0930c-34–0930c.

Stiles, F. G.; Skutch, A. F. (October 1989).A guide to the birds of Costa Rica.Ithaca, NY: Cornell University Press.ISBN0-8014-9600-4.

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