Christmas swiftlet
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C. e. natalis
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| Collocalia esculenta natalis Lister, 1889
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The Christmas swiftlet (Collocalia esculenta natalis), also known as the Christmas glossy swiftlet or the Christmas cave swiftlet, is a small bird in the swift family Apodidae. It is endemic to Christmas Island, an Australian territory in the eastern Indian Ocean.
Contents
Taxonomy
The taxon was described in 1889 by Lister. It has usually been considered a subspecies of the glossy swiftlet (Collocalia esculenta). However, Christidis and Boles (2008) treat it as a subspecies of the cave swiftlet (Collocalia linchi).[1] Here it is kept as a subspecies of the glossy swiftlet pending further study of its genome.
Description
The Christmas swiftlet is a small swiftlet some 9–11 cm in length. It is mainly glossy blue-black or green-black above, with dark grey underparts relieved by a prominent white belly and vent.[2]
Distribution and habitat
The swiftlet is restricted to the 135 km2 Christmas Island where it is commonly seen in large numbers in flight above the tropical rainforest that covers 75% of the island, as well as over other terrestrial habitats there. It nests mainly in caves in the limestone cliffs surrounding the island.[3]
Behaviour
Breeding
The swiftlet breeds deep in caves, in almost total darkness. It builds a small cup-shaped nest for its clutch of two eggs, high up on the cave wall and often sheltered by a stalactite. The nests are made of dried palm fibres and lichen and are cemented to the cave wall with the bird’s saliva.[4][5]
Feeding
The swiftlet feeds aerially on flying ants and other insects.[6]
Status and conservation
Garnett & Crowley (2000) considered the swiftlet, along with a suite of Christmas Island’s other endemics, as critically endangered, with the principal threat coming from the yellow crazy ants which were accidentally introduced to the island. The threat is not only that of direct ant predation of swiftlet nestlings, but also indirectly from potentially massive changes to the ecology of the island caused by the ants.[7] Sometimes the bird breeds in hollow trees and these nests are susceptible to attack by the ants, but the ants do not enter the limestone caverns that are the principle breeding site and are not therefore likely to impact directly on the swiftlet. An application made in 2006 to list the swiftlet as threatened under the Environment Protection and Biodiversity Conservation Act 1999 was unsuccessful.[8]
Notes
References
- Beeton, Robert S. (Chair, TSSC). Advice to the Minister for the Environment and Heritage from the Threatened Species Scientific Committee (TSSC) on Amendments to the list of Threatened Species under the Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act): Collocalia esculenta natalis (Glossy Swiftlet (Christmas Island)).[1]
- Christidis, Les; & Boles, Walter E. (2008). Systematics and taxonomy of Australian birds. CSIRO Publishing: Melbourne. ISBN 978-0-643-06511-6
- Garnett, Stephen T.; & Crowley, Gabriel M. (2000). The Action Plan for Australian Birds 2000. Environment Australia: Canberra. ISBN 0-642-54683-5 [2]
- Higgins, P.J. (ed). (1999). Handbook of Australian, New Zealand and Antarctic Birds. Volume 4: Parrots to Dollarbird. Oxford University Press: Melbourne. ISBN 0-19-553071-3
