Biology & Evolution

Plight of bats flies under the radar

Big-eared-townsend-fledermausFear of Ebola and the turbines used for wind farms pose a critical threat to an animal fundamental to our ecosystems.

The sun goes down and as the shadows lengthen, small patches of darkness detach from roof eaves and sail towards nearby trees, crisscrossing the sky.

In medieval Europe bats were synonymous with witchcraft and black magic. Later, Bram Stoker’s Draculacemented into our collective consciousness the image of a crepuscular, blood-sucking fiend.

In West African countries, bats are synonymous with the deadly Ebola virus, which has killed thousands of people, even though only specific bats are carriers rather than all bats.

But without them our agricultural systems would collapse, with disastrous financial consequences, and natural ecosystems would struggle to survive.

“Insect-eating bats, which make up more than 90% of the bat diversity, are the only group that is known to eat night-flying insects,” says Ernest Seamark, director at South Africa-based conservation group AfricanBats. “These insectivore bats can consume about 25% to 50% of their own body mass in insects per night.”

He cites the example of the Natal long-fingered bat, where populations at De Hoop in the Western Cape and Gatkop Cave in Limpopo – estimated to contain about half a million bats – will eat about 4.5 to nine tonnes of insects a year.

Friends of the farmer
This is particularly important for farmers. Not only do bat populations control agricultural pests but also the various pathogens, such as plant fungi, that the pests carry, says Seamark. Research by Peter Taylor, a professor at the University of Venda, found that bats fed on stink bugs in macadamia plantations. These bugs can result in crop losses of up to 80%, according to the department of agriculture, forestry and fisheries.

Fruit bats are also “known for seed dispersal, which leads to forest regeneration”, Seamark says. “Work in South America … has shown that if the fruit passes through the gut of a fruit bat, there is a much higher germination rate than that of the same … fruit passing through the gut of a bird or primate. The bat intestine seems to coat the seeds with a natural fungicide,” he explains.

But bats, the second most diverse mammal group in the world with more than 1 350 species described, are under threat from many quarters, with each continent – and even country – having its own set of bat-related concerns.

Citizens in West African countries had, until recently, relied on bat meat as an important part of their diet, Alexandra Kamins, a research analyst at the Colorado Hospital Association, wrote on Australian academic news site The Conversation.

The United Nations has cautioned people against eating bush and bat meat, following the Ebola outbreak in West Africa. According to the World Health Organisation, about 5 000 people have died from Ebola and more than 13 000 cases have been reported.

“The West African epidemic is thought to have started when the virus crossed over from infected wildlife into the human population and subsequently began spreading between people,” the UN said. “The Ebola virus is transmitted by direct contact with the blood and body of infected people and animals. And fruit bats – usually eaten dried or in a spicy soup – are thought to be the most likely reservoir species for the virus.”

The rest of this article is available on the M&G’s website.

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