Seychelles sheath-tailed bat Coleura seychellensis
Historically the Seychelles sheath-tailed bat was found on the islands of Mahé, Silhouette, Praslin and La Digue. There was one record of a bat in the Amirante islands but this appears to have been a vagrant individual, rather than a resident population. Historical records suggest that it was common in the past but it is now extremely rare. It is a cave-roosting species, found in the caverns and passages formed under jumbles of granite boulders at low altitudes.
For several years the Nature Protection Trust of Seychelles studied the species on Silhouette using an infra-red CCTV system into one roost. This allowed monitoring to be undertaken without disturbing the bats. Much of our knowledge of the species derives from this monitoring.
The bats feed at night on insects. They show a strong preference for beetles, particularly late in the year, just before breeding. Beetles have high protein and fat contents and these provides the nutrition vital for females preparing for breeding. They also eat large number of moths but tend to avoid the highly abundant flies, which are nutritionally relatively poor. This determines the distribution of the bat breeding colonies: they need to be close to areas with abundant beetles, and such areas are becoming increasingly hard to find as habitats deteriorate. There is also some evidence of bats gleaning beetles from leaves, as well as catching them in flight.
The breeding season is late November to April, corresponding to the wet season of the north-west monsoon. This is the main breeding season for most bats and birds in Seychelles and is the period when insect food is most abundant. A single baby is born either at the end of November or in March. A harem breeding system was reported from studies of the now extinct population on Praslin island but this was not observed on Silhouette.
New-born baby bat visible in cennre of picture:
Predators of the bats are not known. It has been speculated that introduced barn owls feed on them and there is an anecdotal report of an owl attacking bats on Mahé, but this has not been published. Bats have been observed being agitated at a time when rats were present in a roost. It is unlikely that they are predators of the bats but do cause disturbance.
Publications on Seychelles sheath-tailed bat ecology: