Threatened species: 5 key facts on the Mauritian flying fox

Originally published in French in a Mauritian newspaper and targeting the Mauritian audience and some of the local misconceptions.

© Jacques de Speville

1.What is the Mauritian flying fox?

The Mauritian flying fox (Pteropus niger) is a species of fruit bat, found only in the Mascarenes. Majority of individuals of this species are found in Mauritius, where it is the sole survivor of three species of frugivorous bats that once occupied the island. There are misconceptions that the species is a bird or that it live in caves. But the fruit bat is a mammal that roost in trees in colonies that can consist of about a dozen to a few hundred of individuals.

2. Is there too many flying foxes in Mauritius?

From an ecological standpoint, there is not too many of the fruit bats on the island and there never was. The survival of the Mauritian flying fox is mostly dependent on the population that exist in Mauritius which is currently decreasing and facing multiple threats. It is estimated that there is about 62,500 fruit bats in Mauritius. Of these, only 37,700 of the individuals are mature (both male and female) and able to contribute to the next generation. Flying foxes are known to have a slow population growth and females mostly give birth to one single baby per year. Unfortunately not all of these young survive long enough to reach maturity .While it is likely that the population of the Mauritian flying has increased in the past few years, given the biology of the species, it is less likely that this was a substantial rate of increase. The current beliefs that there are a lot of bats now, with some even claiming millions, can be explained by people just seeing them more often. Seeing them more often is not equivalent to having more bats. It is more likely a sign that there is a lack of food in the native forests and thus they need to go out of their native habitats more often to be able to find food.

3. Why is the Mauritian flying fox threatened of extinction?

Mauritian biodiversity as a whole is highly threatened. Following human colonisation, several species have completely disappeared including our famous dodo, giant tortoises and one species of fruit bat. Another species of fruit bat, the Rodrigues flying fox that used to be found here is now locally extinct. Hunting and extensive habitat loss are mostly to blame. In the span of 380 years of human colonisation, Mauritius lost most of its native forests. Currently only about 5 % of the original forest remain and less than 1 % is of good quality. Degradation of the native forests due to invasive plants poses a serious threats to the Mauritian flying fox as flower and fruit production, which are are important sources of food are reduced. Illegal hunting, accidental deaths on powerlines and cyclones poses additional threats. Now mass culling need to be added to the list. Over the span of 14 months, at least half of the world’s population of the Mauritian flying fox was destroyed due to the two successive mass culls in 2015 and 2016.

4. Can the Mauritian flying fox go extinct?

Mauritius fruit bat
© Jacques de Speville

Yes. The history of Mauritius is already a cautionary tale. One of the argument put forward to justify the mass cull of the Mauritian flying fox its that it is just a population control that will not exterminate the species. However not all species are the same. Some takes months, while others take years to reach maturity. Some reproduce several times in a year while others reproduce only once. Some produce several babies at a time while some produce only one at a time. Some are found widespread across a continent while others are found in only one small location such as one small island. Some are facing imminent and mutliple threats like habitat loss while others are thriving. For a species like the Mauritian flying fox that is threatened by multiple threats, that have slow population growth and that can have their population drastically reduced by unpredicatble cyclones, such ‘population controls’ are equivalent to death sentences.

5. Does it matter if the Mauritian flying fox goes extinct?

Yes. Loosing the Mauritian flying fox is also losing many other species that depend on it. Following the extinction of many animals, the flying fox is now the only species responsible for the dissemination of large native trees species in Mauritius. Seed dispersal is important because small plants that grows further away from their mother tree have greater chances of surviving . This means that on its own the flying fox has a very important role in maintaining the unique biodiversity in Mauritius including our native forests and the species in it. Without the flying foxes, our already highly threatened biodiversity and the ecosystem services that they provide (provision of water, protection of lagoons etc.) will decline.

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