Photo credit: Harish Prakash
The philosopher Thomas Nagel wrote that it is impossible to fully know a creature like a bat in 'What is it like to be a bat?' But there are ways we can gain some insights on them. Take the example of the insectivorous bat, Megaderma spasma that roosts in old, abandoned, and relatively undisturbed buildings during the day. Come twilight, the bats leave their roost to find food and return late at night or early in the morning, occasionally with a bush cricket prey. Where does the bat spend its night searching for food in an agricultural landscape in which plantations and remnant forests are interspersed with each other? Does the bat spend equal time between the forests and plantations? What could influence the bat's decision? These are some of the exciting ecological questions we asked in our latest research publication.
To observe where the bats go, we glued radio transmitters on their backs and tracked their locations. We then used satellite images in which you can visually tell apart a forest patch from a plantation to prepare a habitat map of the area. With these two pieces of information, we were able to say where on the habitat map the bats’ locations were and observed that the bats were more likely to be found in forests than plantations. So, why do these bats prefer forests over plantations?
Maybe the differences are in the number of insect prey between forests and plantations. To test this, we deployed insect traps in the area and collected insects. But contrary to what we expected, we found no difference in the overall numbers of insects between forests and plantations. But a bush cricket prey species of the bat, Mecopoda, was found in greater numbers in forests than plantations, suggesting that forests may have more prey than plantations for the bat.
These results show how important these remnant forest patches are for an insectivorous bat. Conserving these forests in agricultural areas will not only help in the persistence of bats in the landscape but also in the maintenance of overall biodiversity and the ecosystem services that forests provide, both of which are crucial for our own future survival.
Reference: Prakash, H., Saha, K., Sahu, S., Balakrishnan, R., 2021. Ecological drivers of selection for remnant forest habitats by an insectivorous bat in a tropical, human-modified landscape. Forest Ecology and Management. 496, 119451. https://doi.org/10.1016/j.forec