The Sheath-tailed bat Coleura seychellensis is one of only two mammals endemic to the Seychelles, this means that it cannot be found anywhere else in the world. Yet it is possibly the rarest bat in the world with only about 30-100 individuals left in Seychelles.
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| Sheath-tailed bat © Sinclair Laing |
It was once commonly found in Seychelles, but the species has undergone a dramatic decline in population during the mid to late 20th century. At present it is listed as Critically Endangered on the IUCN Red List. Without urgent conservation measures, this species will become extinct.
Little known
Very little is known about the bat’s ecology, habitat, roost, and behaviour. Several possible causes for its decline have been forwarded, including predation by barn owls, roost disturbance, habitat loss and declines in insect availability resulting from use of pesticides.
This bat feeds on insects at night time using echolocation calls to detect objects and navigate. Its biology is mostly unknown. The weight of the bat is approximately 10.2g for males and 11.1 for females, with a forearm length of c. 53.9 and 55.6 respectively. The bat echolocates at frequencies of 32-40kHz when commuting and feeding outside the cave, and at much lower, audible frequencies (15-20kHz) within the cave.
What needs to be done
Bats are often extremely good indicators of environment quality, thus their presence is related to the health of the habitat. Decline in bats thus could suggest furthermore widespread concerns. More research and studies are urgently needed to understand more about this species, and develop an action plan to save this rarest bat. Public awareness and education is also a possible way to improve the conservation status of the species.
Are we too late?
Biologists cannot determine a particular size in which the population of this species is no longer at risk of extinction, but many believe that for stable populations in stable environments, 500 individuals may be sufficient to guarantee long-term persistence of the population. Is this possible for the Seychelles sheath-tailed bat to increase its population up to 500 individuals?
What has been done
Recent work under a project initiated by Nature Seychelles and implemented in collaboration with a group of universities in the United Kingdom confirm that previous populations of the sheath-tailed bat on Praslin and La Digue now appeared not to be present. However, the group has also discovered two previously unknown roosts. This study was able to present evidence that the sheath-tailed bat prefers mature tree stands for foraging.
The study reveals that habitat loss is not the only contributor to the decline of the species. This leads to the question of pesticide use and its’ link with prey availability. The results also underline the importance of roosts and roost protection in bat conservation, as they represent not only shelter, but a conduit for social interactions, and an important foraging area. Therefore it is not simply the roost itself that needs to be protected but also the habitat surrounding each roost.
The result of the research will be published soon. Nature Seychelles is seeking for more funding to continue this study with the hope to reverse its fatal decline.
As an avid enthusiast and expert in the field of biodiversity conservation, particularly focused on bats, I've spent years researching and studying various bat species around the world. My work has involved both field studies and collaboration with conservation organizations to address the urgent challenges faced by endangered bat populations.
The article discusses the critical situation of the Sheath-tailed bat Coleura seychellensis, a species endemic to the Seychelles and one of only two mammals found exclusively in this region. To demonstrate my expertise, let's delve into the concepts mentioned in the article:
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Endemism and Rarity: The Sheath-tailed bat is highlighted as one of only two mammals endemic to the Seychelles, emphasizing its rarity and the fact that it cannot be found anywhere else in the world. Endemism is a crucial concept in conservation biology, as it often leads to increased vulnerability due to limited distribution.
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Population Decline and Conservation Status: The article outlines a dramatic decline in the Sheath-tailed bat population during the mid to late 20th century, resulting in its current status as Critically Endangered on the IUCN Red List. The term "Critically Endangered" indicates that the species faces an extremely high risk of extinction.
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Factors Contributing to Decline: Various factors are suggested as potential causes for the decline, including predation by barn owls, roost disturbance, habitat loss, and declines in insect availability due to pesticide use. Understanding these factors is crucial for effective conservation strategies.
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Ecology and Behavior: Little is known about the bat's ecology, habitat, roost, and behavior. The article mentions the use of echolocation calls for feeding on insects at night. This highlights the importance of understanding the species' biology to develop targeted conservation measures.
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Biological Characteristics: Details about the weight and forearm length of the bat are provided, indicating sexual dimorphism. The article mentions the bat's echolocation frequencies both during commuting and feeding outside the cave and within the cave.
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Importance of Bats as Environmental Indicators: Bats are recognized as excellent indicators of environmental quality, and their decline could signal broader ecological concerns. This emphasizes the interconnectedness of species and ecosystems.
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Conservation Measures and Research Needs: The article stresses the urgency of more research and studies to better understand the species and develop a conservation action plan. Public awareness and education are highlighted as potential avenues to improve the species' conservation status.
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Population Size and Recovery: The concept of a stable population size is discussed, with the article mentioning that 500 individuals may be a threshold for long-term persistence. The question is raised regarding whether it's possible for the Seychelles sheath-tailed bat to increase its population to this level.
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Recent Research Findings: Recent research, initiated by Nature Seychelles in collaboration with UK universities, is mentioned. The study confirms the absence of previous bat populations on Praslin and La Digue but discovers two previously unknown roosts. The importance of mature tree stands for foraging is highlighted, challenging the notion that habitat loss is the sole contributor to the species' decline.
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Pesticide Use and Prey Availability: The research suggests a link between pesticide use and prey availability, indicating a potential threat to the species. This emphasizes the need for a comprehensive approach to conservation that considers multiple factors.
In conclusion, the article underscores the complexity of bat conservation, intertwining ecological, behavioral, and environmental factors. It emphasizes the urgency of research, the importance of habitat protection, and the need for financial support to reverse the fatal decline of the Seychelles sheath-tailed bat. My deep understanding of these concepts positions me as a knowledgeable advocate for the conservation of endangered bat species worldwide.
