The flying mammals: Bats 

Many people, many communities even, are afraid of bats. In fact, recently, bats are suspected to be the main cause of the COVID-19 outbreak by being the source of coronavirus (SARS-CoV-2) that causes Covid-19. But bats are the victims of misinformation; they provide greater benefits to the ecosystem and humanity than harm.
Facts about bats
• There are 1,401 bat species in the world of which 142 species (about 10%) occur in South Asia and 128 species occur in India.
• Bats are the only mammals capable of flight. In order to make flight possible, bats digest their food extremely fast, sometimes excreting within 30 to 60 minutes of eating. That helps them keep their weight down.
• Almost all bat species hang upside down. Their feet have evolved to be relaxed in a clenched position (difficult for a human to imagine). When they’re ready to fly, they let go and gain momentum from falling, since their little legs and wings can’t give them the kind of lift birds get. However, there are six species of bats that don’t hang upside down. Most of these bats have suctioning pads on their limbs that let them stick to leaves or other surfaces.
• Many of these bat species have adapted to urban environments, living in gardens, urban parks, and even roosting around our homes, without posing a threat to their human neighbours. 
• Bats and human beings have coexisted for hundreds of thousands of years.
• Bats provide enormous benefits including pollination, seed dispersal, and pest control, worth billions of dollars annually.
Bats drink nectar from night-blooming flowers and while they do, pollen gets dusted off on their fur. They transport his pollen to other plants and in this way, they help in pollinating many fruit and vegetable plants.
Bats are attracted to the smell of ripe fruit and selectively eat only ripe fruits from orchards. They swallow the whole fruit and, while doing so, separate the pulp and spit out the seeds on the ground in the forest. This helps regenerate the forests. Spitting out seeds leads to faster regeneration of forests than excreting out seeds – in the case of the latter, out of 100 seeds, only ten or so might come up as plants since they’ve been subjected to digestive juices. With the extent of deforestation we are doing, conservation of bats will help balance this.
Insectivorous bats are really small. They leave their roosts at around 6.30 am in the evening and while foraging feed on insect mass about 25% of their body weight. Each one consumes 3000 – 4000 mosquitoes per night! So in a roost of ten bats, imagine how many mosquitoes are eliminated from that particular area.
Bat droppings, also known as guano, are high in potassium nitrate (saltpeter) and are often used as fertilizer. The saltpeter can also be extracted for use in gunpowder and explosives, and bat guano was an important resource for that purpose during the American Civil War. Bat guano has also been found to preserve fossils.

How do bats hear?
Bats use echolocation to locate objects around them.  Echolocating bats use echolocation to navigate and forage, often in total darkness. How does this work?  It is a combination of echo+location. The animal emits sounds out into the environment and listens to the echoes of those calls that return from various objects near them. They use these echoes to locate and identify the objects. Echolocation is used for navigation, foraging, and hunting in various environments.
Bats emit sounds in the frequency range from 11,000 to well over 200,000 Hz. Remember humans can only hear from 20 Hz to 20,000 Hz. Hence bats mostly emit sounds in the ultrasound frequency, much higher than what we can hear. They generate this sound via the larynx and emit the sound through the open mouth or, much more rarely, the nose (as in the horseshoe bats).
How can the bat tell if an object is near or far? The distance estimation is called ranging. It is done by measuring the time taken between the animal's own sound emission and any echoes that return from the environment. An amazing fact is that the bat can tell whether the sound reached its left ear first, or its right ear! From this time difference as well as the difference in the relative intensity of sound at each ear, the bat gets information about the horizontal angle from which the reflected sound waves arrive!  The pattern of echoes that are reflected by the tragus, a flap of skin in the internal ear, is also used to estimate the angle.  So the bat can tell the direction and distance to many objects as well as the size of each object, the and avoid them when flying.
At the most basic level, echolocation is based on the neural structures in the bat's brain. It needs to calculate the difference between the two ears to very small fractions of a second.
Only the smaller species of bats use echolocation as their main means of orienting themselves. Bigger bats can see better than humans. Sight is a blessing and a curse, however, because sight can override echolocation signals. For instance, a bat may fly into a window because it sees light outside, even if echolocation tells it the surface is solid.

Bats and COVID-19
• Bats do not spread COVID-19; it is being transmitted from humans to other humans.  SARS-CoV-2 virus strain of SARS-CoV species is very different from BatCoV species found in bats.
• There is no evidence that bats directly infected humans with COVID-19 in the first place.  Although, the SARS-CoV-2 is genetically related to the BatCoVs, and belong to the same genus Betacoronavirus, they are different.  The genetic similarity between BatCov and SARS-CoV-2 ranges only 80–96%.  For a better perspective, humans and chimpanzees are 98% similar genetically.
• Scientific investigations are pointing to a chain of events that may have involved bats but most likely only through an intermediate animal.  SARS-CoV-2 is closely related to BatCoV and Pangolin-CoV (80–96% and 91% similarity respectively.

Bats and humans conflict
Many bat species are in trouble and need our help to survive. Threats to bats include direct persecution, change in quality and quantity of habitats, pollution, the decline in food resources, excessive use of pesticides and pest control activities.  
Two bat species are protected by the Indian Wildlife (Protection) Act: Salim Ali’s Fruit Bat, a southern Western Ghats endemic species occurring in Kerala and Tamil Nadu, and Wroughton’s Free-tailed Bat known only from the Barapede Cave in Karnataka and the Siju Cave in Meghalaya.
Eight species are threatened with extinction in South Asia as per the IUCN Red List. It includes one Critically Endangered, three Endangered, and four Vulnerable species.
Bats are facing existential problems due to the increased impacts of human-induced changes in natural habitats. They are also threatened due to various superstitions that sees bats negatively. This causes irreversible damage to already diminishing populations of these wonderful animals.
Killing bats will not stop the spread of COVID-19, but would adversely affect the conservation status of bat populations, and all the benefits they provide to us like control of mosquito-borne diseases such as dengue, chikengunya, malaria, etc., pollination, and forest regeneration to combat the climate crisis!
We have to learn from our experience and not take any hasty decisions that will be more damaging to humanity in the long term. Wild animals are natural reservoirs, and some species act as safety barriers for many zoonotic diseases that have the potential of becoming pandemics in very little time.
Conservation scientists and bat biologists have taken up the responsibility to dispel myths and create awareness about how wrong and unscientific it is to blame bats for COVID-19 outbreak and its spread. Undoubtedly, the spread of the COVID-19 pandemic needs to be checked, and it can be, only by breaking the chain of human-to-human transmission. It is crucial to have a long-term plan to curtail the outbreak of such diseases by stopping certain human practices, the consumption of wild animals, and the widespread destruction of natural habitats ensuring prevention of such terrible events in the future.
Sources: Encyclopedia Britannica, Wikipedia, Zoo's print, Vol 35, No. 4, 2020 https://www.zoosprint.zooreach.org/index.php/zp/article/download/5669/5086