Documenting Billion-Dollar Bats

Dr. Sara Bumrungsri, a leading bat ecologist, invited us to help document the essential roles of Cave Nectar Bats (Eonycteris spelaea) in pollinating some of SE Asia’s most ecologically and economically valuable plants near Hat Yai in Thailand’s Songkhla Province. We set up our bat photo studio in Sara’s lab at the Prince of Songkhla University, caught two cave nectar bats in mist nets set beneath durian flowers in an orchard, tamed them so they would go about their normal activities in Merlin’s enclosure, then brought them fresh flowers so he could photographically document their importance as pollinators.

Though it may sound easy, in reality it was extremely challenging. The flowers were often high up in trees and didn’t become fully open and loaded with nectar till well after dark. Fortunately, Sara was an expert tree climber, having practiced climbing coconut palms as a youth. He and his graduate student, Tuangit Sritongthuay (nick-named Fon) pitched in to help find and obtain flowers, and our volunteer helper, Jeff Acopian and I took turns sitting up with Merlin till 3 to 5 AM, helping organize flowers into sets indistinguishable from what one would see if photographing them in a tree top, which of course is impossible. Often we’d have to sit perfectly still for an hour or more at a time between bat visits through seemingly endless nights.

Merlin is never satisfied till he has several near perfect pictures in which the bat is not only clearly seen pollinating the flower, but is also in a cute pose. Often flowers are good for only a few quick visits before they wilt, and if a bat approaches from the wrong direction it may get all the nectar and pollen with what Merlin disgustedly refers to as “butt shots” being the only photos possible.

The story we came to tell involves the vital, but often misunderstood roles of Cave Nectar Bats as pollinators. Though durian fruits sell for billions of dollars annually in SE Asia, only a few growers actually understand the essential contributions of bats, mostly cave nectar bats. Some durian farmers even kill the very bats that pollinate their crops. They see flower petals and anthers falling to the ground soon after bats visit and mistakenly conclude that the bats are harming their flowers!  By dropping no longer essential parts of flowers, durian trees are likely helping bats find those that haven’t yet been pollinated.