- The Indian flying fox is crucial for pollination, seed dispersal and ensuring biodiversity and ecological balance. But its population is on the decline.
- A recent study has documented the fruit bat’s roosting colonies and the characteristics of its roost trees in Kurukshetra, Haryana.
- The study contributes to a deeper understanding of the bat’s behavioural ecology and may inform conservation strategies aimed at preserving their habitat and population, say the researchers.
A comprehensive study has documented roosting colonies of the Indian flying fox, a bat species, and the characteristics of roost trees in Kurukshetra district of Haryana. As these large bats are highly selective about where they roost, understanding their roost site selection is the first step towards their long-term conservation.
Fruit bats are vital for ecosystem health, aiding the survival of over 114 plant species worldwide. Among these bats, the Indian flying fox (Pteropus medius), especially, is crucial for pollination, seed dispersal, and nutrient cycling, a process that enables the flow of nutrients through the environment. However, despite its ‘Least Concern’ status on the IUCN Red List, studies show the Indian population faces decline due to threats like habitat loss, electrocution, urbanisation, and hunting, among others.
“Understanding the significance of Indian flying foxes in ecosystem health is vital for their conservation and the continuity of their ecosystem services. Therefore, the study areas were chosen to reflect the distribution, population dynamics, behaviour, and conservation status of Indian flying foxes, ensuring broader applicability and relevance,” says Parmesh Kumar, co-author of the study and research supervisor from the Department of Zoology, Kurukshetra University.
Site selection
Research was undertaken in all four tehsils (Pehowa, Thanesar, Ladwa, and Shahbad) of Kurukshetra district, guided by several criteria. The primary consideration was the significant population of Indian flying foxes, confirmed through extensive surveys.
“Kurukshetra offers an ideal habitat for Indian flying foxes, with abundant roosting opportunities provided by large trees with dense foliage, accommodating sizable colonies during daylight hours,” says Ritu Devi, lead author and research scholar from the Department of Zoology, Kurukshetra University. The area is easily accessible for researchers and equipped with essential infrastructure for fieldwork, including accommodation options, transportation facilities, and resources for necessary field data collection.
“Conservation issues such as habitat degradation, disturbance, electrocution risks, and exposure to extreme heat are prevalent in the area too, necessitating the need for research to address and mitigate these challenges,” says Kumar.
To begin with, field surveys were conducted in the district from January 2021 to March 2021, to identify the Indian flying foxes’ roosting sites. Initial information about the roosting sites was gathered through direct interaction with local residents. The identified sites were then surveyed every month from April 2021 to March 2022, to collect data on roost characteristics and the colony size of the bats. Their numbers were counted using the direct roost count method with the assistance of field binoculars and were also photographed.
Various parameters of the roosting tree, such as tree species, origin (exotic or native), circumference, diametre at breast height (dbh), and tree height, were recorded early in the mornings before the arrival of bats to roost. Data on the number of trees used by bats, the type of roost (permanent/temporary), habitat of each roosting site, and roost status were also recorded.
“Roost tree characteristics such as height, circumference, and dbh, were considered as independent units for statistical analysis. We also assessed the relationship between bat abundance (colony size per tree) and the height, dbh, and circumference of the roost tree,” says Devi.
Know it all
A total of 233 trees from seven families, eight genera and nine species served as roost trees for the bats. These were primarily located near water bodies (60%), followed by agricultural fields (20%), and roadside plantations (20%) within the Kurukshetra district. “However, eucalyptus was the predominant species, comprising about 70.94% of the total roosting sites. The preferred roosting trees were tall with broad canopies, offering protection from predators and adverse weather conditions,” says Kumar.
With regards to population dynamics, 80% of roosting sites were permanent, with individuals sighted year-round, while 20% were temporary, with observations limited to specific months annually. According to the study, at the temporary roosting sites, the bats undertook local migration during peak mating season, and in peak summer and winter months, to more favourable roosts where a large aggregation of individuals occurred. Migration during peak summer and winter season may also be due to unfavourable temperature and weather conditions in this region.
Insights into the diurnal behaviour of Indian flying foxes revealed daily, monthly, and seasonal variations. The bats typically returned to the same roosting sites each day, with movement patterns influenced by factors such as food availability and weather conditions. Significant fluctuations in population size were observed between seasons, with maximum numbers recorded during peak mating season.
The study also identified 15 distinct diurnal roosting behaviours, with sleeping, grooming, wing flapping, and wing spreading being the most common. These behaviours varied across different hours of the day, months of the year, and seasons. “Additionally, two mating patterns, dorsal and ventral mating, were observed, providing insights into the reproductive dynamics and social interactions of Indian flying foxes in the study area. Such findings contribute to a deeper understanding of their behavioural ecology and may inform conservation strategies aimed at preserving their habitat and population,” says Kumar.
The road ahead
The findings underscore the critical importance of habitat preservation, particularly large and tall trees near water bodies, for the Indian flying fox conservation. The study authors observed bats hovering over the surface of the water, dipping their bodies to drink and cool themselves. According to the researchers, key strategies should include protecting remaining forested areas and restoring degraded habitats to provide suitable roosting sites and foraging areas. Community engagement through awareness programs and education initiatives is also vital for fostering positive attitudes towards the bats and promoting coexistence.
“Encouraging sustainable agricultural practices can help preserve foraging habitats and minimise exposure to harmful chemicals. Additionally, effectively managing roosting sites, mitigating conflicts between Indian flying foxes and humans, and conducting further research on their ecology are essential for conservation efforts,” says Kumar.
While findings from the research in the Kurukshetra offer valuable insights and guidance for other areas occupied by the bats, the researchers advocate for careful consideration of local context and validation through additional research for effective conservation action.
Read more: Darkness-loving bats are being nudged out of the shadows
Banner image: The Indian flying fox spotted in Haryana. Image by Ritu Devi.
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