The Sousouri Bannan or Seychelles Sheath-tailed Bat is possibly the rarest bat in the world. It is also an endemic of Seychelles, which means that the estimated 70 individuals that exist in the world are only found in Seychelles. Although historically it was found on four granitic islands - Mahe, Silhoutte, Praslin and La Digue - it is now believed to occur only on Mahe (around 40 individuals in three roosts) and Silhouette (32 individuals in one roost).
The bat is listed as Critically Endangered by IUCN and is considered close to extinction. Nature Seychelles' Bringing Bats off the Brink project has been monitoring the bat roosts on Mahe in order to evaluate threats to the bat and discover the possible cause of the decline of the species. This would enable action to be taken to bring back this rare and unique mammal from the brink of extinction.
Monitoring began in 2004 through a project called Bats on the Brink funded by the BP Conservation Programme (BPCP) and
Valmont setting up insect traps
"It is believed that the main threats to the bat are habitat destruction, disturbance of roosts, food shortages resulting from over use of pesticides - this species being purely insectivorous, and possible predation by barn owls". Says David Derand, Nature Seychelles’ Science Coordinator. “Further investigation of these factors is vital to understanding the decline of the bat. Apart from keeping a tally of the numbers at the roosts on Mahe, we are also interested to uncover information about food abundance particularly in relation to the influence of new potential developments in the vicinity of the roosts.
Two Nature Seychelles members – Ian Valmont and Camille Hoareau - are working with technical staff on this project. Both are very experienced and highly trained field workers. In the past months, they have been recording dusk emergence of the bats and have recently laid insect traps to collect insects around the roosts for study on food abundance and diversity.
A most critical emerging threat to the bats is that of development around the roosts in Mahe. The bats appear to be loyal to these roosts and the foraging locations around them all year round. It is now clear that the roosts used by the bat and their surrounding areas must be given protection.
“One of the roosts is on private land, and so far the land owner has shown a readiness to protect both the roost and the surrounding area”. Says Terence Vel, also part of the monitoring.
Also essential is measures to protect the bat by law to afford it elevated status.
Follow up activities have been supported by the Follow up Award of the BP Conservation Programme (now Conservation Leadership Programme ) and Conservation International.