In the dense tropical forests of a remote Seychelles island, a tiny colony of bats, fewer than 100 strong, represents the final stand of a species once abundant across its archipelago. The Seychelles sheath-tailed bat, a creature most people will never see, is now one of the rarest mammals on Earth.
Remaining Individuals
Primary Habitat Island
Conservation Status
Conservation Scientists
Deep in the Seychelles archipelago, where conservation scientists outnumber tourists, lies an island so protected that 200 researchers guard species found nowhere else on Earth1 . Silhouette Island remains the Indian Ocean's best-kept secret, where 93% of the land exists as pristine national park and critically endangered creatures cling to survival in their last earthly refuge1 .
Location: Seychelles Archipelago
Highest Point: Mont Dauban (751m)
Protected Area: 93% National Park
Access: Boat Only
This isn't just another tropical paradise plastered across Instagram feeds. This is a living laboratory where boat-only access and strict conservation protocols keep the curious masses at bay, preserving something extraordinary for those willing to seek it out1 . Here, the Seychelles sheath-tailed bat represents one of conservation's most urgent success stories, its population slowly recovering from near-extinction under the watchful eyes of dedicated scientists1 .
The Seychelles sheath-tailed bat (Coleura seychellensis) is a sac-winged bat found only in the central granitic islands of the Seychelles2 . These small, insectivorous mammals weigh a mere 10-11 grams (0.35-0.39 oz) with a body length of just 55-65 mm (2.2-2.6 in)2 4 . They display a dramatic color pattern of deep reddish-brown to almost black on their wings and back, with their underside showing shades of gray or lighter brown4 .
These bats differ from most bat species in their social structure. While many bats roost in massive colonies, sheath-tailed bats form harem groups typically comprising just 1-2 males with multiple females2 4 . They are nocturnal insectivores that roost communally in caves and rock crevices, emerging at twilight to feed2 .
Scientific Name:
Coleura seychellensis
Weight:
10-11 grams
Length:
55-65 mm
Status:
Critically Endangered
Population:
50-100 individuals
Habitat:
Caves & Rock Crevices
Historically, the species was probably abundant throughout the Seychelles, but it has suffered a dramatic decline over the past 30 years2 5 . The International Union for Conservation of Nature lists this bat as critically endangered, with current estimates suggesting fewer than 100 individuals survive in the wild2 4 . The largest known population resides on Silhouette Island, with smaller roosts potentially existing on Mahé, Praslin, and La Digue2 .
| Location | Population Status | Key Notes |
|---|---|---|
| Silhouette Island | Largest remaining population (high of 32 bats recorded) | Primary conservation site with intensive monitoring3 5 |
| Mahé | Possibly extant but small | Historical habitat severely compromised2 |
| Praslin and La Digue | Possibly extant but small | Fragmented populations if present2 |
| Global Population | 50-100 individuals | Critically endangered status5 |
The decline of the Seychelles sheath-tailed bat results from a combination of human-caused threats that have devastated their population.
The Seychelles islands were not settled until 1772, but impacts were severe in the early 1800s when over 99% of lowland forests were cleared for coconut plantations3 . This massive deforestation destroyed the bats' natural habitat and hunting grounds. Invasive plants like cinnamon and kudzu vine further degraded the ecosystem, reducing the availability of native insect prey that the bats rely on for food2 3 .
Invasive species followed the first explorers and settlers, and now rats and cats are well established on almost every island3 . These non-native predators pose a constant threat to the bats and their young. The species' exceptionally small population size also makes it vulnerable to natural disasters like cyclones, whose intensity may be increasing due to climate change.
Modern conservation science employs sophisticated tools to study elusive creatures like the Seychelles sheath-tailed bat without disturbing their fragile populations.
| Research Tool | Function | Application in Seychelles |
|---|---|---|
| CCTV with Infrared | Non-invasive roost monitoring | Records behavior and enables accurate population counts without disturbance3 |
| Acoustic Monitoring | Records echolocation calls | Tracks bat activity and distribution through unique vocal signatures1 |
| Baited Remote Underwater Video (BRUV) | Marine ecosystem assessment | Monitors health of surrounding coral reefs and marine food sources1 |
| Bat Detectors | Electronic survey equipment | Helps locate bats by identifying their distinctive echolocation frequencies6 |
Infrared cameras provide non-invasive observation of bat behavior and accurate population counts.
Specialized equipment records and analyzes bat echolocation calls for tracking and identification.
GIS technology maps critical habitats and monitors environmental changes over time.
One of the most critical breakthroughs in understanding the Seychelles sheath-tailed bat came from addressing a fundamental problem: how to accurately monitor the remaining population without disturbing them. Traditional observation methods proved inadequate because the bats roost in dense clusters where individuals are virtually impossible to count accurately3 .
"Often a group will be counted and will then move, as the bat move you realise that what you took to be one bat is actually three. By the time you have realised this the other bats have regrouped and the count is confused again"3 .
This counting challenge hampered conservation efforts for years, making it difficult to track whether populations were declining, stable, or recovering.
In 2006, Dr. Justin Gerlach and his team installed a CCTV camera inside the main bat roost on Silhouette Island3 . This innovative approach allowed for continuous monitoring without human presence that might disturb the colony. The methodology included several key components:
A fixed CCTV camera was positioned to capture the main roosting area of the La Passe roost, the largest known colony3 .
The system included infrared technology designed to record nighttime activity within the roost when bats are most active3 .
Unlike periodic human observations, the camera provided uninterrupted surveillance, capturing natural behaviors unaffected by researcher presence3 .
The footage allowed scientists to study social structure, roosting behavior, and breeding patterns over extended periods5 .
The implementation of CCTV monitoring generated unprecedented insights into the biology and behavior of this critically endangered species. The camera provided clear evidence of population numbers, revealing that the main roost contained several dense clusters of bats that could now be accurately counted during periods when they spread out naturally3 .
Most significantly, the continuous monitoring allowed researchers to potentially confirm breeding patterns. As Dr. Gerlach noted, "It has been speculated that they have a breeding season in April in addition to the main breeding season in December. With the camera working properly we may be able to prove that idea"3 . Understanding reproductive cycles is crucial for timing conservation interventions.
The research also demonstrated the viability of non-invasive monitoring techniques for extremely sensitive species, setting a precedent for conservation work with other endangered bats worldwide.
| Monitoring Method | Recorded Population | Key Limitations | Data Quality |
|---|---|---|---|
| Traditional Visual Counts | Fluctuating counts (16-32 bats) | Human disturbance, bat movement during counts, limited observation time | Inconsistent, potentially inaccurate3 5 |
| CCTV Monitoring | More accurate and consistent counts | Initial technical challenges with infrared system | Higher accuracy, continuous data, behavioral insights3 |
The Seychelles sheath-tailed bat represents more than just another entry on the endangered species list. Its plight highlights the fragile nature of island ecosystems and the devastating impact of human activity on specialized species. As one of only two bat species in the Seychelles, its potential extinction would represent an irreplaceable loss to the archipelago's biodiversity5 .
Bats consume massive quantities of insects, including agricultural pests and disease vectors.
As indicator species, bat population health reflects overall ecosystem condition.
Bats worldwide play crucial roles in ecosystems as insect controllers, pollinators, and seed dispersers. The loss of such species can have cascading effects on entire ecosystems, impacting everything from agriculture to forest health. The conservation efforts aimed at saving the sheath-tailed bat therefore represent a much broader commitment to preserving ecological balance.
Conservation efforts involve partnerships between UNESCO, the Critical Ecosystem Partnership Fund, local NGOs like Nature Protection Trust of Seychelles and Nature Seychelles, and international universities1 5 6 . These collaborations support everything from biosafety protocols preventing invasive species introduction to training local communities in conservation techniques1 .
As development pressures continue in previously isolated areas of Seychelles, the work to protect this species becomes increasingly urgent3 . The story of the Seychelles sheath-tailed bat serves as both a warning and an inspiration—a testament to what we stand to lose, but also to the dedication of those working tirelessly to ensure that such unique creatures don't vanish from our planet forever.
For those interested in supporting conservation efforts for the Seychelles sheath-tailed bat, information is available through the Nature Protection Trust of Seychelles and the Island Conservation Society.