Two subspecies are recognized: Coleura seychellensis seychellensis from Mahé and Praslin, and C. s. silhouettae from Silhouette and La Digue (Hill 1971, Rocamora and Joubert 2004).

The Seychelles Sheath-tailed Bat (Coleura seychellensis) is assessed as Critically Endangered under Criterion C2a(i) because its population size is estimated to be fewer than 100 mature individuals, the population is declining, and all subpopulations are small; the largest known roosting cave at La Passe (Silhouette) has numbers oscillating between 16 and 46.

This insectivorous bat is endemic to the Seychelles and is currently found from 0-100 m asl on the islands of Silhouette and Mahé (Gerlach 2004, Bristol 2023). It is considered to be extinct on La Digue and Praslin where it was last seen in 1979 and 1997 respectively (Bambini et al. 2006). A single record is known from Sainte-Anne where it is believed to be a vagrant (G. Rocamora pers. comm. 2021). There are four threat-based locations at the four known roosts sites. Acoustic transects conducted inland and on the North Coast have not yielded any additional records (Bambini et al. 2006).

The species’ extent of occurrence (EOO) is 218 km² was calculated by minimum convex polygon around the species' extant range. The area of occupancy (AOO) is 16-164 km², with the minimum calculated with a 2x2 km grid over the four known roosts and the maximum from the species' extant range. Currently, the number of locations, AOO, and EOO are not thought to be declining or undergoing extreme fluctuations.

Historically, the species was noted to be 'very common in the neighbourhood of the town of Port Victoria' (Wright 1868). 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 (Gerlach and Taylor 2006). Decreasing sizes of guano deposits suggests that the magnitude of decline over the last century may have been as high as 90%. By the 2000s, the global population was believed to be fewer than 100 mature individuals (Rocamora and Joubert 2004, J. Gerlach pers. comm. 2008). In 2023, the number of individuals counted inside known roosts varied between 41 and 84 (Bristol 2023). The smallest known roost is home to only 3-7 bats whereas the largest in La Passe cave on Silhouette Island is home to 16-46 individuals (Bristol 2023). 

The species’ population is likely organized into two subpopulations that are restricted to Silhouette and Mahé islands, the larger of which is on Silhouette Island and includes one of the four known roosts and an estimated 50% of the total population (Bristol 2023). While the species’ population is decreasing, there is no evidence to suggest extreme fluctuations in the species’ population. The number of subpopulations is stable.

This species has been recorded from coastal boulder field caves with stable cool temperatures and access into native palm woodland or marsh habitat (Gerlach 2004, Joubert 2004, 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). The species has been recorded in various locations across the southwest coast of Mahé as well as on Silhouette. Foraging sites have been identified away from known roosts on both islands and include forested areas, roads, marshes and estuaries as well as coastal disturbed habitats (Bambini et al. 2006, Barbastella Echology and Protect Paradise Seychelles 2023, Bristol 2023). Abandoned roosts have been recorded from all four islands in the species’ historical distribution (Burgess and Lee 2004).

The species is known to feed predominantly on Lepidoptera, Coleoptera and Diptera with an apparent increased reliance on Coleoptera during the breeding season (Gerlach 2008). 

Pups have been observed between November and April in 1977-1980 (Nicoll and Suttie 1982) and more recently in May 2015 (R. Bristol pers. comm. 2015) as well as July 2023 (B. Lewis pers. comm. 2023), suggesting a changing or protracted breeding season that may be due to climate change.

There are three primary threats to the species including the loss and degradation of foraging areas, disturbance and loss of cave roosts, and predation by invasive species. While the greatest loss of habitat likely occurred in the late 1800s and early 1900s when lowland forests were cleared (Gerlach and Taylor 2006), the remaining forests and foraging areas continue to be degraded from ongoing deforestation for agriculture and development (Bristol 2023). Further, the species is exceptionally vulnerable and sensitive to disturbance of roosting caves by humans, and this remains an active threat to the four extant roost sites. Evidence of human activity is regularly recorded inside occupied roosts and old mist-nets have been found inside an abandoned roost in Anse Badamier. Finally, the use of pesticides near roosts or foraging sites could have an indirect impact by decreasing insect populations that the species relies on for feeding (Gerlach 2008, R. Bristol pers. comm. 2024).

Threats from invasive species are extensive from invasive plants (e.g., a morning glory vine, Decalobanthus peltatus and Kudzu vine, Pueraria phaseoloides) and coconut scrub from abandoned plantations expansion into habitat for this species (Gerlach and Taylor 2006). Further, kudzu vines can overgrow roost cave entrances and/or change the temperature gradient within caves (Gerlach and Taylor 2006). Other threats include predation of sheath-tailed bats by introduced predators such as Barn Owl (Tyto alba), cats (Felis cattus), Rattus spp., and Yellow Crazy Ants (Anoplolepis gracilipes) (Nicoll and Suttie 1982, Gerlach 2011, A. Constance pers. comm. 2023, R. Bristol pers. comm. 2023).

The species is not known to be used or traded.

There are several ongoing species-specific conservation interventions for the species. The La Passe cave roost on Silhouette, home to the largest subpopulation, lies just within the boundaries of Silhouette National Park and receives additional protection and management there, but the other three known roosts are not located in protected areas and are on private land. Although the roosts of this species are legally protected (Seychelles Ministry of Agriculture, Climate Change, and Environment 2014), there are major developments planned near the three unprotected roosts. Although C. seychellensis is a trigger species for Key Biodiversity Areas (KBA), the three known roosts that lie outside of Silhouette National Park are not yet recognized as KBAs. There are ongoing education programs with local stakeholders and there is increasing public awareness of the state of the species in schools, to the public, and in the media. 

Compliance and enforcement of protective regulations would benefit the species as it is imperative that all known roosts are protected from planned developments and that, where appropriate, historic roosts receive protection for potential future use. Further, degraded foraging habitats should be protected and restored. On Silhouette, invasive rat and cat populations are controlled in the immediate vicinity of the roost, yet very little management is being undertaken near the known roosts on Mahé. Invasive plants and animals need to be eradicated across the species’ range, especially at all known and extant roosts. Understanding the factors behind the strong fluctuations in numbers between roost counts is important. If it is due to the dispersion to other, unknown roosts, those need to be located and monitored. If other factors are at play, those should be identified and studied to understand their potential long-term effects on the population. 

Additional research is needed to locate additional roosts and explore if the subpopulations on Silhouette and Mahé are connected through dispersal. Periodic monitoring of La Digue and Praslin where the species was extirpated 1979 and 1997, respectively (Bambini et al. 2006) is prudent on the chance the species can recolonise those islands. It is also important that more research is undertaken to better understand the feeding and breeding ecology of this species.