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Don’t blame them for our plight
In Meghalaya, people are living healthy lives even with large colonies of fruit bats around
By Dr Uttam Saikia
They are so plentiful, yet we know so little; they are so beneficial yet we despise them so much! Unquestionably, no other animal fits better than bat to the above narrative.
With over 1,400 species and counting, bats are the second largest group of mammals after rodents in the world. They occur practically everywhere except for the polar regions and a few oceanic islands. And they occur in great numbers, some forming the largest mammalian congregations on Earth!
The evening emergence of an estimated over 15 million Mexican free-tailed bats that roost in Bracken cave in Texas is a sight to behold. Even in our own state Meghalaya, certain caves in Jaintia Hills hold large populations of bat species like large bent-winged bat. In spite of being so diverse and abundant, we know very less about these creatures.
The primary reason for this obscurity is flying and nocturnal lifestyle of bats that makes direct observation difficult. Also, our tendency to look for more charismatic megafauna as study subjects is a reason. Compared to other mammalian species (barring rodents), the life history traits, ecology and systematics of most of the bat species are still unknown to scientists. For the knowledge of common people, it is important to mention that bats are one of the most ecologically beneficial groups of mammals.
Notwithstanding their serious roles in maintaining the health of the ecosystem and farming economy, bats have always been viewed with fear and revulsion because we fear the most which we know the least. This fear has been magnified manifold in view of the current COVID-19 pandemic the humanity has been grappling with.
The scary news items of bats causing COVID-19 has created a fear psychosis so much so that people have resorted to mass killing of bats or evicting or destroying their roost sites. People get horrified by the news of fruit bats dying in numbers which normally happens because of heat stroke during the summer months. But what we know so far is that scientists are not sure about the source of the COVID-19 virus and it is also not confirmed yet whether the virus had jumped from animal host to human.
In fact, there has been a flurry of research focusing on animal origin of SARS-CoV-2, the pathogen for COVID-19. Many of these researches published in renowned science journals pointed towards a possible bat origin of this virus but without any conclusive proof. Some researchers postulated an intermediate animal like pangolin from which the virus might have jumped to human. Some critics even doubted the natural origin theory of this virus and speculated that it could be even man-made.
Hopefully, the definitive answer to the origin of this dreaded virus will emerge in future. However, all the evidences so far do not establish a bat origin of this virus. Yet, from the beginning, there were many news reports holding bats responsible for the current pandemic. The latest and most exhaustive analysis of bat coronaviruses funded by the US National Institute of Health also could not pin point the origin of the SARS-CoV-2. They found that a Rhinolophus (horseshoe bats) coronavirus having a sequence similarity of 96.2 per cent identical to SARS-CoV-2, the closest relative yet found.
However, calculations suggest it would take decades for that bat virus to mutate into the new human pathogen. It is pertinent to mention that coronaviruses are a large family of viruses normally found in birds and mammals. In humans, several coronaviruses are known to cause respiratory infections ranging from the common cold to more severe diseases like Severe Acute Respiratory Syndrome (SARS). Like other mammals, bats also host a number of coronaviruses many of which are innocuous. The large numbers of bat viruses known is because of disproportionately skewed virus hunting in bats compared to other animal groups.
In view of the above, it would be unjust and premature to blame bats for the current disease outbreak. The truth as we all know is that irresponsible actions of human and our continuous encroachment into the wilderness have increased the chances of interaction between wildlife and human. So theoretically, there is a chance of some animal pathogens jumping to human and causing some undesirable effects although in practice, this interspecific jump is not as simple and of common occurrence as it might seem.
For the sake of argument, even if we accept a bat or animal origin of COVID-19, we humans are responsible for its uncontrolled global spread; the animal is least to be blamed.
In fact, bats have very good safety record of living with humans. Our relationship with bats dates back to antiquity and instances of people dying because of bats are far less uncommon than any other wild animal. Many indigenous people eat bat on a regular basis, but there are no reported cases of illness arising out of this practice.
In Meghalaya, this practice of eating bats is of common occurrence especially in Jaintia Hills. People are living perfectly healthy lives with large colonies of fruit bats around or Pipistrelles living in the village huts. Eminent bat biologist and conservationist Dr Merlin Tuttle who has spent around 50 years of his life studying bats throughout the world points out, “Bats have excellent safety record of co-existing with human; Historically, the world’s greatest zoonotic pandemics have not come from bats.”
Yes, there are certain health concerns associated with bats like rabies, Nipah etc. Rabies from bats has been reported from Europe and Americas, but no such instances are known from South Asia. In fact, the Indian Medical Association does not recommend any post exposure prophylaxis (rabies vaccine) after a bat bite.
An overwhelming majority of the rabies cases worldwide are transmitted by dogs, our favourite pet. And unlike a rabid dog, a rabies infested bat will become morbid and will not become aggressive to attack any animal.
Nipah is another disease of public health concern which might have a direct bat connection. In South Asia, it is primarily transmitted through drinking of raw palm juice contaminated by bat saliva or urine as some fruit bats carry this virus. However, this disease is much easier to contain once the source is determined. And any chance of transmission of a bat disease to human is exceedingly less if we minimise contact with them.
From a human perspective too, bats are really useful creatures. From pollination to pest control, bats provide immense ecological and economic services to mankind. Researchers have found that bats have direct roles in pollination of more than 500 species of plants worldwide. Among these species pollinated by bats include varieties of economically important plants like banana, guava, mango, agave and mahua. Needless to say that without pollination, these plants cannot produce seeds and reproduce.
The coastal forests known as mangrove play an important role in protecting the coast from sea surges and coastline erosion. The mangrove systems are one of the most productive ecosystems on Earth and a large number of unique plant and animal species thrive there. Some of these mangrove plants especially of the genus Sonneratia are pollinated by fruit bats.
Besides, fruit bats are responsible for seed dispersal of a number of trees and thus forest dynamics and regeneration. One very significant ecological role of bats is biological pest control which has huge economic consequences as well. One well-publicised research in the US reports that insectivorous bats saves food crops of at least $23 billion every year through consumption of insect pests.
Although no such economic quantification has been attempted in India so far, we can assume that in an agriculture-based economy like India, this will be monumental. A large number of bat species lives in large colonies inside caves. Over time, they create thick piles of guano on the cave floor which have significant commercial value. In ancient times, bat guano was an important source of gunpowder and now also, they have significant values as fertilisers as it is rich in nitrogen, potassium etc.
In many parts of the world, bat guano is commercially harvested. This practice of commercial guano extraction was also prevalent in the early 18th century in Siju cave in South Garo Hills. Bat guano is also one of the major energy sources in resource impoverished cave ecosystem and a large number of invertebrates and their predators thrive forming a unique ecosystem.
To our fortune, Meghalaya is the most diverse state as far as bat diversity is concerned. With over 65 species being reported from the state, this is about 50 per cent of the total bat diversity in the country. It is time that we try to dispel many misconceptions about bats prevailing in our society and look at the in scientific light. It is essential that we ensure protection and welfare of these maligned and misunderstood creatures with whom we are co-existing from time immemorial.
Dr Tuttle is very right in his statement, “Care about bats or not, we should see COVID-19 as a grim reminder that human well-being requires responsible stewardship of nature, not just dominance.”
(The author is a scientist at Zoological Survey of India, Shillong)
(Photo of Hipposideros larvatus, a cave dwelling bat species, contributed by the author)