Unseen benefits of bats outweigh their stigmatised portrayals
In movies from Dracula to Morbius, bats were evocative of monstrosity. In reality, bats can be powerfully effective like the Bat of Gotham, keeping epidemics at bay and ecosystems functional. They deserve our careful understanding
My first visual memories of bats were nothing to be scared of. It was a tropical summer evening, humid and sweltering. Windows were open, fans spinning at max speed. A sudden thump caught my attention—something collided with the ceiling fan. Another thump followed immediately. Then, another—this time, something hit the wall. Then, something dropped on the floor. After the initial shock subsided, I came upon a tiny, furry blackish dead body--about the size of a sparrow--wrapped in a cloth. I vividly recall what I saw under the light. The leafy projection of its pointy nose and unusually long, flattened ears were etched onto my memory.
A pipistrelle is a type of small bat that, in Bangla, is dubbed as ''chamchika'' and uses echolocation much like Marvel's blind hero Daredevil. By producing very low-pitched sounds and gauging the nature of the echoes that gets bounced back to its hypersensitive and large ears, bats can do pretty much everything from tracking down food to communicating with kin to avoid dangers. Unlike Daredevil or any other mammal, bats are the only mammal capable of independent flight.
But the dead pipistrelle did not match anything I watched in any movie or read in any fiction. It did not seek permission or make creepy whispers before barging into an apartment. It was a hapless small bat—perhaps too young, too old or starved and having a bad night— made a wrong turn.
At that time, my then residence was a rapidly developing peri-urban area. With buildings sprouting and old groves vanishing, the changing landscape became unfamiliar to bats.
An evolutionary wonder
Bats might be struggling to tackle man-made obstacles, nonetheless, they form a fascinating taxonomic order; the Chiroptera. Bats are most known for mastering flight and use of sonar. However, it is believed that bats are blind or have poor eye-sight. "Bats, both large and small, have very good vision," says Md Ashraf Ul Hasan, a graduate student at Texas Tech University, US. Larger bats use a rudimentary form of echolocation; a few not at all.
Bats do not lay eggs. They give birth and breastfeed their newborns. They have a mammalian build so much so that they have finger-bones similar to ours. Those bones have become elongated to support thin, extended skin membranes that play the role of birds' wings. The skin flap, patagium, can be present between the legs. Some bats have a long tail—in some, the patagium extends down to the tail; in a few species, the tail dangles free. Some bats sustain on fruits, some on nectars. Some hunt insects and some can even catch fish by diving like a hawk. A few bats drink blood but they do not follow Vlad Dracul, who used to drain his victims to death. Vampire bats are one of the smallest types of bats. They do not swoop on to victims as a savage swarm either. Movies are more often than not, misrepresentative when it comes to the portrayal of wildlife.
Do bats spread disease?
Bats do not transmit disease deliberately. David Quammen, the writer of the famous book Spillover, made a factual remark, ''deadly pathogens, by nature, can live in animal hosts as reservoirs. Removal of animals or getting too close to them can infect humans,"—akin to HIV, Ebola, COVID-19 among many others. The pattern was the same in every case. It was traced down to us getting dangerously close to wild animals. Read: we do not stop eating wild animals.
Spillover stresses that "understanding the chain of transmission of emerging infectious disease from animals to humans needs careful understanding." In the case of bats, the picture is not clear yet. But, most often, it started with our palate for bushmeat. What was done in Wuhan did not stay in Wuhan.
Yes. Bat can spread deadly disease as we keep taking away bats' food, destroying bat caves and eating bats—as grotesque and risky as it might sound, we still do. Bat Conservation International, the NGO dedicated to bat research and conservation, highlights the fact that ''destruction of habitats and exploitation of wildlife increase the risk that new pathogens will jump into the human population." A 2019 study in the journal Mammal Review assessed the link between human activities and fruit bats in the spreading of Ebola and found "a significant link between forest loss and fragmentation that potentially altered the natural ecology of virus resulting in virus outbreaks.'' Simply put, due to dwindling numbers of bats, viruses are being forced to adapt and infect new hosts; and are finding human physiologies to be a good replacement.
Scenario: Bangladesh
Seasonal death by Nipah virus is common in northern and western Bangladesh, as is the practice of eating bats. The potential source of the spreading disease was deduced to be the drinking raw date juice and our habitual tendency of not worrying about bats. Bats are carriers of Nipah virus and have a taste for date palm juice. Heating raw date juice to a certain temperature can eliminate any virus that might be spilled from bat saliva, urine or faeces. In Bangladesh, we still have a long way to go as we still deem killing the bats, an easier remedy. I can recall news of tree felling in parks to get rid of bats and subsequent collection of bat corpses meant for illegal bushmeat markets.
Dr Tigga Kingston, Professor and supervisor of Hasan at Texas Tech University, says, "bats are frequently paired with scary, negative emotions, so we must work to link a positive perception of them.''
Bat research in Bangladesh is still in its infancy. New bat species are recorded every year. Two new bat species were recorded recently by researchers of Jahangirnagar University after a hiatus of more than a century. Hasan is assembling a team of young bat scientists. ''We need to build up a museum collection to understand bats, their positive roles and potential risk of meddling with them," Hasan echoed David Quammen. "We need to have a genetic database of all sorts of bat derivatives," the bat ecologist commented on tackling bat-borne diseases.
What if all the bats are gone?
Insect-eating bats are effective pest controllers. "Insectivorous bats can prey on 500 to 3000 insects per night, and fruit-eaters and pollen-drinkers are proven pollinators" said Hasan.
Dhaka University holds a good population of bats. Afternoons are rife with regal, leisurely flights of large fruit bats; but for how long I wonder, noticing all the infrastructure cutting deep through a once green campus. Bats are not built to squeeze through the concrete mazes.With less and less trees, bats will leave cities someday, viruses will not.
