Seychelles sheath-tailed bat Coleura seychellensis
The Seychelles sheath-tailed bat is a Critically Endangered species known only from the islands of Mahé, Silhouette, Praslin and La Digue. In the 1800s it was described as being common on Mahé but declined throughout the 1900s. Today the known roost sites on Praslin and La Digue have all been abandoned. The only significant roosts are on Silhouette island where two caves have been located. These caves are part of a single system of passages in a boulder field. Three small roosts on Mahé have been located.
The Seychelles sheath-tailed bat is classified as Critically Endangered by IUCN, is the 25th EDGE (Evolutionarily Distinct and Globally Endangered) species listed by the Zoological Society of London. It is a trigger species for the Alliance For Zero Extinction highlighting the importance of Silhouette island for the conservation of the species. In 2012 it was highlighted by the Bat Specialist Group as one of the species most likely to become extinct in the near future.
The Silhouette roosts were monitored by the Nature Protection Trust of Seychelles from 1997 until 2010. During that time conservation management saw the population increase from 18 bats to a maximum of 40. These low figures are an indication of the precarious status of this bat.
NPTS installed an infra-red CCTV system into one roost so that monitoring could be undertaken continue without disturbance to one of the world's rarest and least-known mammals. This revealed important new information on the behaviour and ecology of this threatened species.
Habitat restoration around the roosts and the feeding areas resulted in increases in beetle populations (favored by the bats during the breeding season) and consequently a highly successful breeding season in 2007-8. After 3 years of decline the population recovered to the maximum of 32 by April 2008. 2008 proved to be a good year for the bats, with a new record of 37 bats set in December. At this time at least one bat was occasionally returning to an abandoned roost, and it seemed that the Silhouette population was finally starting to recover. Further progress was recorded in 2009 when numbers increased to 40. In early 2010 12 of the bats dispersed to start a new colony.
On Mahé island an estimated 30-50 bats survive in three isolated roosts, all threatened by development and habitat deterioration. In 2009 NPTS worked with the Seychelles Ministry of Environment to propose conservation of the Mahé populations of sheath-tailed bats.
Publications on the Seychelles sheath-tailed bat: