Cocos finch (Pinaroloxias inornata)
| Also known as: | Cocos Island Finch |
|---|
| Kingdom | Animalia |
|---|---|
| Phylum | Chordata |
| Class | Aves |
| Order | Passeriformes |
| Family | Emberizidae |
| Genus | Pinaroloxias (1) |
| Size | Length: 12 cm (2) |
| Weight | 16 g (3) |
Cocos finch is classified as Vulnerable (VU) on the IUCN Red List (1).
Darwin’s finches are a group of fourteen closely related birds, celebrated as an example of how natural selection can lead to the evolution of different species from a single lineage (3). While thirteen of Darwin’s finches are found on the Galapagos, the fourteenth member is confined to the small island of Cocos, just over 600 kilometres to the northeast (2) (3) (4). Like the ground finches of the Galapagos, the adult male plumage of the Cocos finch is completely black (2) (5), while the female Cocos finch is blackish-brown above with olive-brown streaks, and paler buff below with black streaks (2). Darwin’s finches are characterised by a wide spectrum of beak forms, with the slender, pointed beak of the Cocos finch being particularly distinct (2) (5) (6).
The Cocos finch is endemic to Cocos Island, around 500 kilometres to the southwest of Costa Rica (2) (4).
Inhabits the lush, tropical forest covering much of the island, but is also found in other habitat types including Hibiscus thickets along the coast and patches of disturbed vegetation (2) (6).
Compared with most of its Galapagos relatives, the Cocos finch is more of a generalist in its foraging habits. However, individual birds tend to specialise in a small selection of the various techniques employed by the species as a whole. For instance, while some Cocos finches may forage mainly for insects resting on foliage, others may feed predominately on soft fruit or nectar (2) (6) (7). The comparatively wide range of foraging habits exhibited by the Cocos finch is thought to be indicative of the absence of competition (6).
Little is known about the reproductive biology of the Cocos finch, but the clutch size appears to be two eggs and nesting occurs year round with a peak between January and May (2) (8).
Although rats and cats are potential predators, and feral pigs, goats, and deer are known to reduce habitat quality, the Cocos finch appears to be fairly tolerant of disturbance and remains relatively abundant. However, because it is confined to such a small area, there are concerns that a single catastrophic event could eliminate the entire Cocos finch population (2).
Although there are no conservation measures presently underway for the Cocos finch, there are future proposals to assess the role of various factors on the species’ abundance (2). Furthermore, the whole of Cocos Island is designated a National Park and a UNESCO World Heritage Site (2) (4). As a World Heritage Site, Cocos Island is subject to a management plan that aims to ensure the island’s conservation through the protection of sensitive sites, the elimination of alien species, the promotion of scientific research, and the control of tourism (4).
To find out more about conservation on Cocos Island see:
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Friends of Cocos Island Foundation:
http://www.cocosisland.org
For more information on this and other bird species please see:
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BirdLife International:
http://www.birdlife.org
Authenticated (21/04/09) by Professor Peter R. Grant, Department of Ecology and Evolutionary Biology, Princeton University.
http://www-dept-edit.princeton.edu/eeb/people/display_person.xml?netid=prgrant&display=Emeritus%20Professors
- Endemic: a species or taxonomic group that is only found in one particular country or geographic area.
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IUCN Red List (October, 2008)
http://www.iucnredlist.org -
Birdlife International (March, 2009)
http://www.birdlife.org/datazone/species/index.html?action=SpcHTMDetails.asp&sid=9614&m=0 - Hau, M. and Wikelski, M. (2001) Darwin’s Finches. In: Encyclopedia of Life Sciences. John Wiley & Sons, Chichester.
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UNEP-WCMC (March, 2009)
http://www.unep-wcmc.org/sites/wh/pdf/Cocos%20I.pdf - Grant, P.R. and Grant, B.R. (2007) How and Why Species Multiply: The Radiation of Darwin's Finches. Princeton University Press, Princeton, New Jersey.
- Smith, N.M. and Sweatman, H.P.A. (1976) Feeding habits and morphological variation in Cocos finches. Condor, 78: 244 - 248.
- Werner, T.K. and Sherry, T.W. (1987) Behavioral feeding specialization in Pinaroloxias inornata, the "Darwin's Finch" of Cocos Island, Costa Rica. Proc. Natl. Acad. Sci. USA., 84: 5506 - 5510.
- Grant, P.R. (2009) Pers. comm.