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Today is International Bat Appreciation Day, a celebration initiated by Bat Conservation International. This day encourages us to learn more about these species and the role they play in nature. To celebrate this very special day, the Mauritian Wildlife Foundation (MWF) wishes to raise awareness around the Mauritius Cave Bat (Mormopterus acetabulosus). This insectivorous bat is endemic to Mauritius, and plays a vital role in the control of insects that can be destructive to agriculture and human health.
Also called Mauritius Free-tailed Bat, the Mauritius Cave Bat is unique in its own way. It is a very small bat reaching 10 grams when fully grown. The bat is a very quick flyer and barely makes any noise while in flight. Contrarily to popular belief, this bat is not blind though it prefers using its excellent echolocation skills to catch insects which constitute its exclusive diet.
This Mauritius Cave Bat is only found in caves, as its name indicates, often in colonies reaching several thousand individuals. This bat only leaves the lava tunnels during the night for foraging. A single bat can eat as much as 6000 to 8000 insects in one night! It can eat pest insects that potentially affect sugarcane and litchis. “The cave bat can eat the equivalent of its own body weight during one night. While eating these insects, the cave bat is in fact helping farmers protect their crops”, says Ashmi Bunsy, MPhil/PhD candidate at the University of Mauritius, currently studying the ecology of the free-tailed bats and Flora Coordinator at the Mauritian Wildlife Foundation.
The Mauritius Cave Bat will also feed on mosquitoes, thus protecting humans from diseases such as Dengue, Chikungunya or malaria.
According to Ashmi Bunsy, it is believed that the Mauritius Cave Bat previously had natural predators, such as the Round Island Boa (Casarea dussumieri) which is now limited to two northern Mauritius islets or the extinct Mauritius Lizard-owl (Mascarenotus sauzieri). Owl bones have been collected at Plaines des Roches and Kanaka caves by palaeologist, Julian Pender-Hume in 2007.
The Mauritius Cave Bat faces many threats, according to Ashmi Bunsy. Their total reliance on lava tunnels makes the species very vulnerable to cave closures, damage, deterioration and development (agriculture, construction, road works --). In 1988, 142 caves were listed. Sadly, the number of caves suitable for Mauritius Cave Bats are declining due to adverse human activities.
Another threat to the Mauritius Cave Bat is the extensive use of pesticides. These chemicals affect bats indirectly, through the food chain; bats are feeding on thousands, if not tens of thousands, of poisoned insects, leading to their own ill-health or demise eventually.
Finally, in common with the majority of bats around the world, the female Mauritius Cave Bat gives birth to one pup per year, which makes the species vulnerable to Climate Change. As natural calamities like cyclones tend to become more intense, their occurrences can drastically reduce the bat’s population. Moreover, episodes of high temperatures will affect insects, raising their mortality rates. This will therefore affect food availability for the Cave Bats and their pups.
The Mauritian Wildlife Foundation would like to call for greater protection of our caves, as well as stricter control over the use of pesticides, so that the Mauritius Cave Bat can continue to thrive and play its insect controlling role that is beneficial to nature and human health.
