Mauritius fruit bat. (Credit: istock)

In a move that has outraged conservationists, the government of the Indian ocean nation of Mauritius is planning to kill off nearly 20,000 Mauritius fruit bats, a protected species that is found only on the island.

Mauritian fruit growers are claiming that the bat is responsible for significant agricultural losses, but scientists say that’s dubious — and that the planned number of bats killed could imperil the entire species.

It wouldn’t be the first time human actions have threatened a Mauritian animal. Over the past few centuries, several species have disappeared from the island, the most famous of these being the Dodo, which was hunted to extinction by the beginning of the 18th century. Since then, the Dodo has become a poster child for the conservation movement, and a grim warning to the world — and to the island of Mauritius, in particular — of the dangers of the unsustainable killing of wildlife.

The Mauritius fruit bat, sometimes referred to as the Mauritius flying fox, is a fruit-eating bat with leathery wings and, of course, nocturnal habits. It makes an impressive figure, with its fox-like features, golden-brown fur and a wingspan that can exceed two feet. The species has faced many threats over the past few decades from hunting, habitat loss and the effects of cyclones, which can have devastating impacts on the island and its inhabitants. The species was considered critically endangered in the 1970s and 1980s, when it began a long recovery. It was listed as endangered by the International Union for the Conservation of Nature (IUCN) in 2008 and downlisted to “vulnerable” in 2013 after showing some improvement. It’s still considered a protected species in Mauritius.

In addition to its precarious conservation history, the bat has a complicated relationship with the people of Mauritius. Fruit growers on the island have argued for years that the bats are highly destructive to their crops and should be viewed as pests. In response, the government of Mauritius initiated a small-scale cull in 2006, which is believed to have only led to the deaths of a few thousand of the bats, at least partly thanks to its protected status, which prohibits shooting them after dark. And in 2009 the government began subsidizing the cost of protective nets that could be placed around trees in order to keep out fruit-eating animals.

Despite these measures, fruit growers have reported continued damage to their produce — and on Oct. 6, at the Sixth Assembly of the Mauritian National Parliament, Minister of Agro-Industry and Food Security Mahen Kumar Seeruttun announced plans for another controlled cull, this time with aims to eliminate 18,000 bats. During his announcement, the minister cited reports from the Food and Agricultural Research and Extension Institute, which claim that bat-related damage “recorded for the year 2014 for litchi reaches as high as 73 percent in orchards whilst damage caused to mango is estimated up to 42 percent in backyards,” he said, according to a transcript of the meeting. 

“In view of the huge economic losses being incurred by fruit growers, bold and urgent action is required to reduce the bat population and hence reduce the damages caused to fruits,” Seeruttun said during the assembly. He said the government expects to cull about 20 percent of the fruit bat population starting this month, and with current government estimates placing the population at about 90,000 strong, this would amount to killing 18,000 bats.

While the culling has not yet begun, according to Vincent Florens, an associate professor of ecology at the University of Mauritius, the proposal calls for the Mauritius Special Mobile Force, the government’s main security force, to carry it out by shooting the bats.

Officials from the Ministry of Agro-Industry and Food Security, including Seeruttun,  did not respond to repeated requests for comment.

Conservationists are concerned that the island has overestimated how many of the bats it still has and how much damage they are causing to fruit trees on the island. The National Parks and Conservation Service concluded that the island had 90,000 bats left by counting bats in different roosts at different times. But that is problematic because Mauritius fruit bats often switch roosts if they’re disturbed in the middle of the day, Florens said. This means that there’s a high possibility many of the bats were counted multiple times in different places, he said. 

A more accurate population estimate would be closer to 50,000, Florens said, meaning a cull of 18,000 bats would take out about 36 percent of the population. And this could be disastrous for the species.

The “implementation of a cull will very likely result in an up-listing of the species from Vulnerable to Endangered or Critically Endangered on the IUCN Red List, which will damage the reputation of Mauritius as a world leader on conservation,” IUCN said in a recent statement. 

The Mauritian Wildlife Foundation has also publicly opposed the cull, noting in a statement: “Currently the evidence we have does not support a cull.”

The foundation also drew attention to several other ethical issues associated with the cull in its statement. For one thing, it noted, culls by shooting can result in bats being wounded and taking several days to die. Additionally, many Mauritius fruit bats are pregnant or raising babies during this time of year. This means that many babies could die if their mothers are killed — and it also means that a disproportionate number of female bats could be killed, as they’re likely to be slower and easier targets than the males this time of year, said Ryszard Oleksy, a postdoctoral researcher at the University of Bristol who’s currently involved in researching the bat’s impact on fruit trees in Mauritius.

Oleksy said his research also indicates that culling the bats would be of little benefit to Mauritian fruit growers. Preliminary results indicate that bats are responsible for about 11 percent of damaged fruit on large mango trees and less than 3 percent of the damage on small trees, he said. Similarly, Oleksy said his research has so far suggested that bats account for less than 10 percent of the damage observed on litchi trees.

He found that other animals, such as birds and rats, are also responsible for a significant amount of the damage caused to fruit trees. And Florens, the University of Mauritius professor, also noted that inefficient harvesting techniques, which allow a hefty amount of fruit to go bad before it’s collected, also account for a great deal of wasted fruit on the island, far more so than any damage caused by bats.

The reasons for the discrepancy between Oleksy’s research and the government’s estimates of bat-caused damage are unclear. But Oleksy suggests that part of the reason bats get a disproportionate amount of the blame is because they feed at night and fruit growers are unable to observe them and make accurate estimates of how much fruit they’re destroying.

And the bat’s creepy reputation probably doesn’t help, either. “I think generally bats never had a good reputation among humans,” Oleksy said. “They come out at night, we don’t see them clearly as we do birds, and we’re not used to them because they just fly at night.”

However much the bats may be disliked among the general populace, though, losing them could be catastrophic to the local ecology, Florens said. The bats are important because they help disseminate the seeds of native plants.

A better alternative to culling the bats would be to continue encouraging fruit growers to protect their trees with nets, Florens said. According to Oleksy, one of the reasons this tactic has been unsuccessful in the past is because the nets are not being used properly. Many people only cover the trees’ lower branches or simply drape their nets over the tops of the trees, a strategy that still allows fruit-eating animals to get close enough to nibble at the fruit. A better practice would be to hang the nets on frames that place enough distance between the trees and the netting to keep the fruit safe.

And Florens also suggested encouraging more efficient harvesting practices that don’t allow so much fruit to go to waste, thus cutting down on the fruit growers’ economic losses even more.

That said, Oleksy believes it’s unlikely the cull can be stopped at this point, since it’s already been announced. Both he and Florens said they expect the culling could begin any day nowand according to Oleksy it’s even more likely now, thanks to a new bill allowing for stricter control and management of the island’s biodiversity.

Still, with outcry building, the bats are likely to receive greater international attention if the cull is, in fact, initiated. There’s even been talk of a boycott against Mauritian-grown fruit, Oleksy said.

“People can punish this kind of decision and boycott the fruit, because [nobody] wants to buy fruit from an industry which is so destructive to the environment,” Oleksy said. “That’s one thing which I think is our last resort.”

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