As for ES, there were seeds of 14 species under roosts – seeds bats had clearly moved away from parent plants, suggesting potential for urban seed dispersal. But hey – it’s only seed dispersal if the seeds remain viable. And they do, as evidenced by high germination success. Of course, that was in vitro – recruitment depends on the fate of seeds in the field. And several seeds were in spots where they’ll never become trees either because the substrate is hostile to germination or because people will remove them.
To call it an ES, we must also ask which plants bats disperse. And some are invasive, such as spiked pepper (Piper aduncus). And some, such as Fagraea crenulata, only occur in horticulture, so CYBR could help them escape cultivation. Those would be ecosystem disservices. Still, its most important food plants are native. Like the Tembusu (F. fragrans)– a heritage tree that CYBR ate most often. So, it may help maintain populations of native trees.
Finally, we must ask where CYBR eats. And we can’t really say because we didn’t track them – this would be a good next step in this line of inquiry. Still, finding DNA from an unidentified species of Avicennia, a mangrove tree, 6 km from the nearest mangrove suggests CYBR must at least sometimes forage far enough away from its roosts to disperse native plants over long distances. Besides, it eats fruit from pioneer trees, such as tiup tiup (Adinandra dumosa), and drops seeds in more degraded, urbanised patches. In doing that, CYBR might promote forest succession. And if it eats rare, native trees in Nature Reserves and disperses them outside, then it could help establish urban populations to buffer from extinction.
This thesis (submitted with Drs Elizabeth Clare and Sheema Abdul Aziz) is now in revision, so watch this space. Angela is a biology teacher and award-winning wildlife photographer.