4 reasons to save the bats

Bats have been mythologized for millennia as mystical, elusive and sometimes satanic creatures of the night. Indeed, the cave-dwelling superhero Batman is said to have been inspired by the Mayan "death bat," an animal god of darkness and sacrifice known as Camazotz.  

This image has become more sinister in recent times as bats are said to be the source of zoonotic diseases such as Ebola, SARS and now COVID-19. But researchers say humans are the real culprits since they're destroying habitats and biodiversity that once insulated people from pathogens carried by animals. 

Without the 1,400-odd species of bats that pollinate more plants across the planet than any other animal, biodiversity will continue to decline and the risk of disease increase. 

No bananas without bats 

Bats constitute 20% of all mammals on Earth. Without them, many ecosystems would collapse. It's bats, not the birds and the bees that pollinate flowers in vital food-producing plant species like banana, mango and agave. Bats also disperse and regenerate over 500 types of plants, including cacao beans, as they feed on fruits and spit seeds on the ground to germinate. 

But as they begin their migratory journeys across whole continents every spring, bat roosting habitats from Zambia to Germany continue to dwindle due to deforestation and development. Despite the fact that they do well finding hang-outs in buildings and parks in urban areas, their vast numbers are starting to dwindle. There were once some 200 species of flying fox or fruit bats, but eight are now extinct and another 22 are endangered. Fewer bats will lead to less biodiversity – and fewer bananas.

Even vampire bats are social animals

While most bat species feed on insects or fruit and pollen, there are also three kinds of blood-sucking vampire bats that are all indigenous to the Americas. On very rare occasions, these bats have been found with traces of human blood, though they almost exclusively feed on birds. 

Yet in contrast to their sinister image, a team of German researchers has shown that these blood-suckers are also very community-minded. "They exhibit very complex social behavior," says biologist Simon Ripperger.

"They groom each other's hair," he added. "And they share their food. If a bat comes back hungry from the hunt, other bats in the roost will sometimes regurgitate the blood they've consumed and share it." 

Such awareness includes social distancing in times of ill-health. When a bat is feeling unwell, it performs what Ripperberger calls "passive social distancing" whereby it becomes lethargic and is less likely to call out to its mates for social interaction — not unlike people staying at home instead of mingling with others during the current pandemic. 

Don't blame bats

While vampire bats probably get more attention than their relatively small numbers deserve, many more bat species do host viruses and spread them through the animal kingdom — and increasingly to humans. Ebola, SARS, MERS (Middle East Respiratory Syndrome) and COVID-19 are believed to have originated with bats.

In part due to their high body temperatures, bats have high immunity and can tolerate infectious diseases. In their feverish state, they can host and pass on viruses that then mutate as they spread to other animals. 

The role of bats in the spread of infectious disease is not surprising given that they are both the second most populous mammal after rodents, and are also highly mobile. The only mammal that can sustain flight, bats cover distances of up to 2,000 kilometers on their migratory journeys. 

But while bats are being blamed for pandemics, it is in fact humans who have made themselves more vulnerable to zoonotic diseases, says the #DontBlameBats campaign.

Recent studies have shown that a sharp reduction in biodiversity, especially through deforestation, has reduced the buffer between humans and wildlife that spread pathogens originating in bats.

In some countries there's a push to cull bats because of their association with zoonotic diseases. But bats in fact will be key to re-establishing the biodiversity that will limit the spread of viruses to humans. Bats also devour huge masses of disease-spreading insects, including mosquitoes. Some bats eat more than 1,000 insects per hour.     

They plant forests too

Fruit-eating bats are vital in dispersing the seeds needed to regenerate deforested areas globally. Helping to reforest tropical areas of Southeast Asia, busy bats have also been aiding in the regrowth of African woodland at a rate of around 800 hectares annually.  

Meanwhile, bat species in Madagascar that feast on insect plagues that threaten rice crops are also aiding in the regeneration of deforested lands.

Research by University of Cambridge zoologist Ricardo Rocha shows how rice farmers in Madagascar were cutting down more forest to compensate for crop losses to pests. But with bats (36 species are endemic to the island) helping to save crops by feasting on plagues of insects, Rocha believes there will be less incentive to fell more trees to make way for farming.