Flying Mammals Bats

The vegetarians

Australia has some of the world's largest fruit bats. Many of these can be seen throughout the Wet Tropics, particularly at dusk when they leave their camps in the trees to forage for food during the night. Their main diet is nectar and fruits and they play a vital role in the dispersal of rainforest seeds. They will also take pollen and help to cross-pollinate flowers as they lap nectar. These bats are common in backyard gardens, too - especially when the pawpaws (papaya) have ripened!

The most common is the Spectacled Flying-fox (Pteropus conspiculatus) which boasts a wingspan of roughly one metre (3 feet). A good place to see these impressive bats rise up from the canopy and depart for their daily feed is from a boat on the Daintree River. There are many areas though, even in the inner suburbs of Cairns, where flying foxes can be seen hanging from tree branches during the day. A single young is produced in late spring and females are capable of reproduction at two years of age. These bats have excellent vision and sense of smell and can travel up to 20km in one night in search of food.

Not all the fruit bats are so large. They range in size down to the tiniest Queensland species, the Blossom Bat (Syconmycteris australis), with a body only 5cm (2 inches) long and weighing in at a meagre 15 grams (half an ounce). It shelters under leaves during the day but at night, its pointed snout and brush tongue (similar to the lorikeets) allow it to feast on the nectar hidden deep in flowers, making it an important specialist pollinator of the rainforest.

Some other flying-foxes to look for in this area are the Black (Pteropus alecto), the Little Red (Pteropus scapulatus) and the striking Tube-nosed (Nyctimene robinsoni), easily identified by the yellow spots on its wings.

The insect terminators

The Blossom Bat described above might be a heavyweight compared to some of the insect eating bats! These are the sonar-equipped bats whose calls sound like high pitched shrieks and clicks. Another name for them is microbats (as opposed to the fruit bats which are also called megabats).

There are many species of microbats and identification often requires trapping and detailed examination by an expert. Sophisticated technology is also being used to identify bats by electronic signature analysis of their calls. The majority of microbats roost in caves but several species use tree hollows, tunnels, roofs and under loose tree bark. Most of these bats are very small, having bodies as light as 4 grams (.15 of an ounce) although many of the Wet Tropics species are about 20 grams (.7 of an ounce) and are 4 to 6 cm (1 ½ to 2 ½ inches) long.

Insectivorous bats are usually seen around streetlights at dusk and appear like large, fast flying insects themselves, whirling and turning as they use their sonar to catch insects in mid-flight. When spotlighting in the forest, flashlight beams can attract moths, which in turn, attract microbats. Flashes of their wings can be seen as the bats pursue their prey through the beam of light.

We hear so many reports of wildlife facing extinction, that the story of the Tube-nosed Insectivorous Bat is welcome news. Once credited with being Australia’s rarest mammal, this tiny microbat (it weighs 8 grams) has made a dramatic reappearance thanks to new research techniques. Until 1994 only six of these bats had ever been caught, all of them in the Wet Tropics. But with new trapping techniques - in particular a harp trap of superfine fishing line which fools their sonar, and recent major advances in bat call detection, sensitivity and analysis - many more of these bats have been found in various locations around the World Heritage Area. Tiny transmitters also have been used to track animals to communal nesting sites and learn more about their behaviour. While the bat is still classified as rare, scientific research has been able to shed new light on how we can protect its habitat to help ensure its continuing survival.