A deep look at how bats impact mankind and ecosystems - an engima unravelled!
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The enigmatic bats in natural ecosystems - An analysis
- The story: For centuries, bats have been called sinister, because of their beady eyes and razor-sharp fangs. But these nocturnal creatures aren't that bad! There are more than 1,300 species of bats in the world, making them the second most common group of mammals after rodents. The scientific name for bats is Chiroptera, which is Greek for “hand wing.” That’s because bats have four long fingers and a thumb, each connected to the next by a thin layer of skin.
- More on Bats: They are the only mammals in the world that can fly, and they are remarkably good at it. Their flexible skin membrane and movable joints allow them to change direction quickly and catch mosquitoes in midair.
- There are two main types of bats: microbats and megabats. Most bats are microbats, which eat insects like moths, that come out at night. Vampire bats are the only species of microbats that feed on blood rather than insects. They prefer to drink from cattle and horses, not humans.
- To navigate dark caves and hunt after dark, microbats rely on echolocation, a system that allows them to locate objects using sound waves. They echolocate by making a high-pitched sound that travels until it hits an object and bounces back to them. This echo tells them an object’s size and how far away it is.
- But megabats live in the tropics and eat fruit, nectar, and pollen. They have larger eyes and a stronger sense of smell than microbats but have smaller ears because they don’t echolocate. There are more than 150 species of megabats, which are usually, but not always, larger than microbats.
- Bats and humans: The two have cohabited since time immemorial but the ecosystem services that bats provide are often neglected. Bats can be found nearly everywhere, except in polar regions, extreme deserts, and a few isolated islands. They spend their daylight hours hiding in roosts around the tropics, dense forests, and wetlands. Roosts are where bats go to rest, usually in cracks and crevices that keep them hidden and protected. The most common roosts are existing structures such as caves, tree hollows, and old buildings. Seasons often dictate where any bats choose their homes. depending on the time of year because they hibernate during the winter. For example, in the winter, some may hibernate in caves, and in the summer, they’ll return to an attic. Because good roosts can be hard to find, many live in giant colonies with millions of other bats.
- Why bats are important: Despite all the misconceptions surrounding bats, they are very important to humans and the environment. Insect-eating microbats consume millions of bugs a night, acting as a natural pest control for plants. Thanks to bats, farmers might rely less on toxic pesticides, which costs them crores of rupees each year. Nectar-drinking bats pollinate plants so they can produce fruit. In fact, more than 500 plant species, including mangoes, bananas, and avocados, depend on bats for pollination. Finally, fruit-eating bats help disperse seeds so rainforests can grow, helping to mitigate the effects of widespread deforestation.
- The bats prey on insects in farms, fields, forests and grasslands including agricultural pests and disease-causing mosquitoes. Some bats sip nectar and helps in the cross pollination of flowers.
- They eat fruits and spread the seeds of many important tree species including wild varieties of bananas, guava, cashew, mango, figs, mahua and other fruits.
- Bat droppings (guano) have high concentrations of nitrogen and phosphorous and are widely used as a fertilizer for agricultural crops.
- Spreading diseases: Bats are suspected to be the natural reservoirs for many pathogenic viruses such as Nipah, Hendra, Marburg, Ebola and the now infamous coronaviruses that cause severe acute respiratory syndrome. Evidences are pointing that the SARS-CoV2 virus that causes COVID-19 originated in bats. Despite being reservoirs for viruses, bats themselves never fall sick. That is because in gaining the ability to fly long distances, bats have inherited an immune system that protects them from viruses. It protects them from multiple chronic age-related diseases and makes them age slower, and live longer.
- Human-bat interface: Humans have significantly modified the landscape over the years by cutting the forests, clearing the land for agriculture and development resulting in disturbances to the habitat of bats. Activities such as mining destroy natural cave systems that bats live in. The spillovers are unusual and rare eventsand tend to occur when there is increased contact between humans and wild hosts. Scientists have shown that when bats are disturbed, they become stressed and could shed viruses that they carry, increasing the risk of spillover. Spillovers refer to the transmission of pathogens from their natural host or reservoirs to novel hosts such as humans.
- Ecological balance: Many indigenous peoples are dependent on animals and nature,and have achieved a balance without any harm to both sides. Some have isolation practices such as quarantine following hunting.
- The Bomrr clan in Nagaland have traditionally celebrated the annual bat harvest where they gather at a place called Mimi and smoke a cave full of bats to kill them for consumption. In the process, the bats bite them or scratch them yet there has been no major disease outbreak among the Bomrr clan.
- Why are the Bomrr immune to the viruses in the bats? The National Centre for Biological Sciences (NCBS-TIFR), an aided centre of Department of Atomic Energy, carried out sero-ecological studies on this human-bat interface.
- Precautions: Many precautions can be taken to minimise direct interactions with bats such as (i) Avoid handling or eating bats, (ii) Avoid eating fallen fruits gnawed by bats, (iii) Avoid fruits likely to be contaminated by bat fluids etc.
- Summary: Integrated approaches such as One Health, where human health is linked to that of the environment and animals can result in the best possible outcomes. Global commitment is required for the reduction of habitat loss, and for the preservation and restoration of natural habitats and biodiversity.
- EXAM QUESTIONS: (1) Explain the role played by bats in the ecosystems of the world. (2) Why are bats not victims of the wide range of pathogens their bodies carry? Explain. (3) Explain "echolocation". (4) Why are humans not able to leave the bats in peace, creating spillover potentials? Explain.
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