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'Insect Bats' or 'Microbats'
Photo: C & D Frith
Australia's Cape York Peninsula
Suborder Microchiroptera
Of the two suborders of
bats, these are the bats most people around the world are more familiar with.
This is due to the fact that they are found practically everywhere. They are a
much more diverse group than the 'megabats'; there are microchiropterans that
have evolved to feed on insects, fish, fruit, nectar, blood and even other bats.
They are generally small and
fast, with most living in colonies in dark places where they roost upside down.
The saying 'blind as a bat' is a reflection of the fact that many species have
small eyes and that they tend to rely on another sense to make their way around.
This other sense involves emitting high frequency calls from the mouth or nose
and detecting the 'ultrasounds' as they reflect off other objects. They use this
echolocation sense both to navigate in the dark and to locate their prey.
Many people around the world
fear these bats for various reasons. Many of these reasons are unfounded, but
one has to admit that when examined in the hand, they often have rather
grotesque faces with various foldings in the skin. These convolutions may aid in
making and collecting their ultrasonic calls (Strahan 1998).
Insect bats in Australia
There are six families of
the microchiropteran or 'insect' bats in Australia,
with over 70 species (Egerton 1997). All species in Australia are primarily
insectivorous with the notable exception of the biggest Microchiropteran of them
all, the 'Ghost Bat', that feeds on small mammals, including other bats (Strahan
1998
Additional
Information:
Large-eared Horseshoe-bat: Rhinolophus
philippinensis
This is an insectivorous bat.
It has an elaborate nose-leaf, the U-shaped
lower part looking like a horseshoe.
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It has long ears, is grey-brown above, and
slightly lighter below.
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This small bat weighs only10-12g, has a head and body length of 62-65mm, tail
length of 33-35mm and forearm length of 50-53mm.
Habitat and
Distribution:
Lives in small caves and disused mines,
preferably in warm, humid areas for daytime roosting, a factor that limits their
distribution (in north-eastern Queensland).
It likes areas of dense vegetation such as
closed canopy vine forest that allows only a little light through. It has also been seen
feeding in open forest areas of Cape York Peninsula.
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It is rare in Australia, but common in the Philippines, Kei Islands, Celebes, New
Guinea and Timor.
Diet:
It feeds on moths and other flying insects, detecting its prey by
using ultrasonic 'sonar' calls that bounce off objects and return signals to their
sensitive ears. It usually eats from the ground, or close to it.
Social Behaviour:
This bat does not seem to form large colonies. Scattered
individuals are found in caves, often in association with the Eastern Horseshoe-bat (a
close relative).
It hangs from the ceiling (not against the wall as most species
do) and only forms clusters when juveniles and young are left together while the adults
are feeding.
Additional Information:
- Its flight is similar to that of a butterfly due to its short broad wings. It
hovers and darts among the foliage and close to the surface of water.
- If by accident it lands in water, it can take off directly from the surface as
long as the fur has not become waterlogged.
- It has a very intense ultrasonic call, its pattern of cries consisting of long
constant-frequency portions with a short modulated termination. The call is snorted
through its nostrils and beamed directionally by the nose-leaf. This is an advantage as if
the bat is flying through dense vegetation and eating a moth at the same time, it is still
able to make its call. (Most other bats emit their calls through their mouth.)
- It has large ears that move rhythmically but separately from a forward-pointing
to a lateral direction. This sweeping motion is thought to increase the accuracy of its
echolation and is often observed as one approaches a resting bat.
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