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Coleura seychellensis

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Taxonomy [top]

Kingdom Phylum Class Order Family
ANIMALIA CHORDATA MAMMALIA CHIROPTERA EMBALLONURIDAE

Scientific Name: Coleura seychellensis
Species Authority: Peters, 1868
Common Name(s):
English Seychelles Sheath-tailed Bat
Taxonomic Notes: Two subspecies are recognized Coleura seychellensis seychellensis from Mahé and Praslin, and C. s. silhouettae from Silhouette and La Digue (Hill 1971, Rocamora and Jobert 2004).

Assessment Information [top]

Red List Category & Criteria: Critically Endangered C2a(i) ver 3.1
Year Published: 2008
Date Assessed: 2008-06-30
Assessor(s): Gerlach, J., Mickleburgh, S., Hutson, A.M. & Bergmans, W.
Reviewer(s): Hutson, A.M., Racey, P.A. (Chiroptera Red List Authority) & Cox, N. (Global Mammal Assessment Team)
Justification:
Listed as Critically Endangered because its population size is estimated to number fewer than 250 mature individuals, with no subpopulation greater than 50 individuals, and it is experiencing a continuing decline.
History:
2004 Critically Endangered
1996 Critically Endangered
1994 Endangered (Groombridge 1994)
1990 Endangered (IUCN 1990)
1988 Endangered (IUCN Conservation Monitoring Centre 1988)

Geographic Range [top]

Range Description: This species is endemic to the Seychelles, and is currently found on the islands of Silhouette, Mahé (in the northwest of the island) and Praslin. It is thought to have become extinct on La Digue island and Praslin since 1980s (Justin Gerlach pers. comm. 2008).
Countries:
Native:
Seychelles
Range Map: Click here to open the map viewer and explore range.

Population [top]

Population: The species was noted by Wright (1868) to be 'very common in the neighborhood of the town of Port Victoria'. Joubert (2004) mentions that the species was seemingly still abundant up to the 1970s, and that the use of guano deposits as an indicator suggests that the magnitude of decline may have been as high as 90%. The global population is now clearly very small, and although the precise number is not known, it is believed to be fewer than 100 mature individuals (Rocamora and Joubert 2004; J. Gerlach pers. comm. 2008). The roosting cave at La Passe was recorded to contain 32 bats in total in 2003 (Gerlach 2004, 2008), however, more recently only 27 animals have been recorded roosting at this locality (Justin Gerlach pers. comm. 2008).
Population Trend: Decreasing

Habitat and Ecology [top]

Habitat and Ecology: This species has been recorded from coastal boulder field caves with stable cool temperatures and access into native palm woodland or marsh habitat (Gerlach and Taylor 2006). It appears to need boulder caves with horizontal ceilings; low, stable temperatures; and clear cave flyways not obscured by vegetation (Gerlach and Taylor 2006). Joubert (2004) and Gerlach and Taylor (2006) provide specific details on the ecological requirements of this rare species. Although the species has recently been recorded from three islands, the only occupied roosting localities are known at La Passe and Grande Barbe (their continued presence at this second site was recently confirmed by J. Gerlach pers. comm.), on Silhouette island (Rocamora and Joubert 2004; Gerlach and Taylor 2006), and from two sites on Mahé, the main locality of Cap Ternay containing between 20 and 30 animals, and Anse Major with one or two bats (J. Gerlach pers. comm. 2008). Abandoned roosts have been recorded from all four islands in the species historical distribution. A detailed study of the roosting site at La Passe is provided by Burgess and Lee (2004).
Systems: Terrestrial

Threats [top]

Major Threat(s): Gerlach and Taylor (2004) report that the most catastrophic decline of this species probably occurred in the late 1800s and early 1900s when lowland forests were cleared, converting the mosaic of woodland and open gaps to intensively managed coconut plantations with no shrub layer to support the invertebrate diet of this species. Invasive plants including the Kudzu vine (Pueraria phaseoloides) and coconut scrub from abandoned plantations threaten remaining suitable habitat for this species. Kudzu vine threatens to overgrow roost cave entrances or to change the temperature gradient within caves (Gerlach and Taylor 2004). The species is sensitive to disturbance of roosting caves and this remains a threat to any active roost sites. Other suggested threats have been the predation of bats by the barn owl, Tyto alba, introduced in 1949, and feral cats.

Conservation Actions [top]

Conservation Actions: Rocamora and Joubert (2004) recommend annual census of individuals along established transects; regular sensitive visits to all known roosting localities with additional surveys to locate any additional sites; reevaluation of the species distribution every three or four years; legal protection of all known roosting sites and their immediate surroundings; control of introduced predators (barn owl Tyto alba and cats); habitat protection within known feeding areas; public awareness campaigns; ongoing and additional research into the distribution, ecology and threats to this species. Gerlach and Taylor (2006) also outline the importance of removing invasive vegetation from existing and abandoned roost sites, and restoring lowland forests through the control of coconut and cinnamon, and replanting native vegetation.

Citation: Gerlach, J., Mickleburgh, S., Hutson, A.M. & Bergmans, W. 2008. Coleura seychellensis. The IUCN Red List of Threatened Species. Version 2014.3. <www.iucnredlist.org>. Downloaded on 27 November 2014.
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