The Indian Flying Fox is widely distributed in the Indian subcontinent and is one of the largest bats found in this region, which plays an important role in seed dispersal and pollination.
The Indian Flying Fox (Pteropus medius; formerly Pteropus giganteus) belongs to the family Pteropodidae, with 170 species of bats distributed across tropical Africa, Asia, Australia and islands in the Indo-Pacific. Members of this family are some of the largest among bats. They have big eyes and a keen sense of smell, which they use to forage on fruits and nectar, unlike insectivorous bats that use echolocation to navigate and find prey. Within this family of fruit bats, the genus Pteropus (flying foxes) represents sixty species that are predominantly found in islands and coastal regions. The Indian Flying Fox is among the very few species in this group with a widespread distribution spanning the Indian subcontinent. With a wingspan of up to 1.5 meters, it is one of the largest bats found in India.
Flying foxes started diversifying around 6-7 million years ago, their large flight distances allowing them to colonize faraway islands in the Indian and Pacific Oceans. The subsequent geographic isolation on these islands may have given rise to new species. While we understand the recent evolutionary history of bats in general, pressing questions about the origin of their striking adaptations remain to be answered. This is because of gaps in their paleontological record with an absence of fossils representing the transition of bats to flight and echolocation. Researchers hypothesize that tree- or rock-dwelling ancestors of bats may have started gliding before the evolution of powered flight in these curious mammals.
Given their ability to fly over long distances, fruit bats are ecologically important as pollinators and seed dispersers that can help in the regeneration of forests. At dusk, they emerge from the trees where they rest in colonies, known as roosting sites, and a recent study tracking individual bats found that they can travel more than 40 km in one night. They feed on the flowers and fruit of dozens of different tree species and select foraging sites based on the surrounding tree cover. The small but numerous fruits of Ficus such as banyan/aalamaram (Ficus benghalensis) and peepal/arasamaram (Ficus religiosa) are important food sources for the species. While it is thought that they return to the same roosting site after foraging, males may move between multiple roosting sites during the breeding season. The number of individual bats on a roosting tree is related to its width, canopy size and height. In northern Tamil Nadu, large colonies are seen roosting in trees of Ficus species along with tamarind/puliyamaram (Tamarindus indica) and mahua/kaattu-iluppai (Madhuca longifolia var. latifolia).
Fruit bats are natural hosts for viruses, which can cause zoonotic diseases when there is a spillover of the pathogen to humans. Such transfer may happen when several factors, including ecology, pathogen dynamics, behaviour and host biology - "barriers to spillover infections", coincide in time and space. A recent study reported the importance of fruit bats to the local dispersal of clumps of seeds in cashew and areca plantations in the Western Ghats. Plantation workers collect these dropped fruits and seeds, which can be processed easily, and view bats as beneficial to farming. Researchers advocate for (often simple) strategies to prevent zoonotic transmission in scenarios where people live near fruit bats and call for research and monitoring of bat colonies to detect future outbreaks.
On the IMSc campus, a colony of the Indian Flying Fox can be seen roosting on trees in the lawn east of the main building. While they rest during the day, they are occasionally heard chattering and seen fanning their wings and moving across branches in the canopy.
