Adaptations of the Dawn Bat in the Rain Forest

The small dawn bats (Eonycteris spelaea) of Southeast Asia are well adapted to their rainforest habitat. Their physical structure, diet and social behaviour are all suited to a tropical forest environment that is rich in plant life, but contains plenty of predators. This species is also flexible enough to cope with some of the changes humans cause.

Although dawn bats belong to the fruit bat suborder, rather than the smaller insectivores, they don't in fact eat much fruit. Instead, they consume nectar and pollen, both of which plants provide in abundance in the rainforests.

Because dawn bats get their food from inside flowers, they have developed exceptionally long tongues to access the nectar and pollen. Bats fly and don't need tails for balance or to help them climb rainforest trees. For these reasons, dawn bats only have very short tails remaining, although their ancestors, which were probably arboreal, had long tails. These bats have large eyes, primarily because they are nocturnal and use vision to navigate in dim light. They may also use a simple form of echolocation.

Suitable caves for the bats to roost in during the day are not particularly common in rainforests. Once a population has located a cave, thousands of dawn bats use the cave to sleep in for generations. They are social when they leave the caves to feed, travelling in huge flocks to their food sources. This provides some protection from predators. It is much harder for a carnivore, such as an owl, to take a bat from a flock than to catch a single bat travelling by itself. This is partly because the number of individuals confuses predators and partly because so many bats are likely to spot potential predators early.

A female bat has only one baby at a time. The baby isn't completely weaned for three months, and for the first few weeks, the mother carries it with her. This level of maternal care gives the juvenile bat a good start in life but means the mothers can't have many offspring at a time. They appear to breed twice a year to balance this to a degree.

The dawn bat has successfully adapted to some of the human activity within its range. It now takes a substantial proportion of its food from cultivated fruit trees and crops, where it plays an important role in pollination. Reports indicate that small groups of dawn bats have started using the attics of people's homes as alternatives to caves. This adaptability is one reason the species is not endangered despite the extensive deforestation of its natural habitat.