There are eight species of bats occurring in Tasmania. They are:
- Little forest bat,
- Southern forest bat, Vespadelus regulus
- Large forest bat,
- Chocolate wattled bat,
- Goulds wattled bat, Chalinolobus gouldii
- Lesser long-eared bat,
- Tasmanian long-eared bat,
- Eastern false pipistrelle,
Bats belong to the order Chiroptera, which is comprised of two main groups (suborders) of bats. These are the microchiropteran or small (micro) bats and the megachiropteran (large) bats such as the flying foxes. All of the Tasmanian bats are microchiropteran bats and all belong to the family of evening bats called Vespertilionidae. Bats in this family are insectivorous and have their tails fully enclosed in a membrane. Fruit bats, like the flying fox, lack tails and eat fruit. They do not generally occur in Tasmania, although occassional vagrants have been recorded on the Bass Strait islands, northern Tasmania and, very rarely, southern Tasmania.
Bats comprise one-fifth of all the mammals in the world.This highly successful group of mammals are predominantly a tropical group - given Tasmania's temperate latitude, it is not suprising that it has relatively few species of bat.
Bats are the only group of true flying mammals in the world. Like other mammals, they are warm blooded, feed their young milk and are covered in fur.
The unique feature of bats is their wings. The bones of their forearms are the same as other mammals except that they are longer and lighter. An elastic skin stretches over the forearm bones and attaches to the side of the bat's body making a wing. The length of the bat's forearm is used to help identify different bat species.
What do they eat?
All Tasmanian bats are insect eaters. They are nocturnal feeders and become active at dusk. Bats are opportunistic feeders and most commonly eat moths, beetles, caterpillars, mosquitos and other flying insects. Tasmanian bats do not feed on fruit or blood. In fact, they help control the numbers of many insects including mosquitos and crop pests. Bats can consume up to half their body weight in insects per night.
What is echolocation?
Tasmanian bats use echolocation as a way of locating their food in the dark. Echolocation is a high pitched sound produced in the bat's larynx and directed out through the mouth as a short pulse of ultrasonic sound. When these pulses strike an object an echo of the sound returns to the bat. These sound echoes are collected by the bat's forward-facing ears. The echoes enable bats to judge the shape, texture and distance of any object such as a tree, insect or building. Thus they locate objects by echoes (echolocation).
Bats catch insects in flight. Small insects may be taken directly into the bat's mouth, whilst larger insects are scooped into the bat's wing, transferred to the tail and then eaten. All of the Tasmanian bat species have their own favored way of insect hunting. Some species forage in the upper canopy, whilst others will hunt close to or on the ground. Some bats catch insects in mid air, whilst others seek insects amongst the foliage.
Where do bats live?
Tasmanian bats do not usually live in caves. Generally they live in old hollow trees. They roost, upside down, in these hollows during the day. So it is very important to leave suitable bat roosting sites such as old trees and limbs around farms.
Some bats will roost in alternative shelters such as rock crevices or buildings. The lesser long-eared bat is quite urbanised and is often found in the roofs or walls of houses and sheds. This bats' proximity to urban areas and its method of foraging close to the ground, results in this species being the one most commonly killed by pet cats.
Tasmanian bats are born pink and furless, during late spring or early summer. One or two young are born, depending on the species. During birthing, the mother hangs from her roost site by her thumb claws and catches the newborn baby in her tail membrane. A newborn bat's legs are very well developed allowing them to cling to their mother's fur or the roost site.
Initially baby bat's wings are poorly developed so most species leave their young clinging upside down to the roost site while the mother forages. Adult bats usually forage for around two hours at a time. The mother bat usually leaves her young in a 'creche' situation whilst she hunts. Known exceptions to this are the young of Goulds wattled bat and the little forest bat. The young bats remain attached to their mothers' nipples even during flight.
Bats are born with recurved (bent backwards) teeth which help them cling to their mother. They drink milk directly from their mothers' nipples which are located beneath each armpit. Bats develop quickly and may be fully furred within three weeks. By midsummer most bats have been weaned and are foraging for food themselves.
Bats hibernate over winter, when insects are scarce. The metabolism slows dramatically during this time and they rely on their stored fat reserves. Bats are very vulnerable to any disturbance while hibernating. If they are awakened, they may use up critical energy reserves. Similarly during the day bats go into a torpor which also slows their metabolism and helps them save their energy reserves.
Male bats only produce sperm in summer which makes breeding quite complicated as all bats hibernate over winter. This means techniques such as delayed implantation of embryos or storing of sperm are necessary. In some species the male bat stores sperm over winter while in other bat types, females are responsible for synchronised breeding strategies.
All of the Tasmanian bats are fully protected species and it is illegal to collect or harm them in any way. They are widespread and occur in a range of forest types. Seven of the eight species also occur on mainland Australia. All species appear to be relatively common, although the larger species are probably less abundant (e.g. Goulds wattled bat, Tasmanian long-eared bat and the eastern false pipistrelle). The lesser long-eared bat and the eastern false pipistrelle are often encountered foraging and roosting in urban areas.
The bat virus
In 1996, a previously undiscovered virus, lyssavirus, was found in Queensland's flying foxes (fruit bats). Lyssavirus has since been isolated from an insectivorous bat. This has drawn attention to the need for people to exercise caution and the proper care when handling bats even here in Tasmania. It is important that everyone handling bats wear leather gloves.
Lyssavirus is transmitted when open wounds come into contact with infected saliva or blood. It is not transmitted by casual contact or via urine and faeces.
The virus is related to, but distinct from the rabies virus. The distribution of lyssavirus is unknown. Although there are no fruit bats in Tasmania it may be carried by one of the insect eating species. However these bats are all very small and most species are unlikely to cause a scratch or wound, even when being held.
Tasmanian bats are shy, nocturnal and not aggressive. People only encounter them infrequently, for example when bats become disorientated and cling to curtains or roost in sheds.
What to do if you are scratched or bitten by a bat
Anyone who is injured (scratched or bitten) by a bat in Tasmania should seek prompt medical attention.
If you find a bat
Sometimes bats enter homes or may be found in unusual places because they have been caught out by a sudden change to cooler temperatures (e.g. sides of buildings). If a bat has flown into the living room area of your home encourage them to leave by opening windows or doors at night. If you need to catch and handle a bat then ensure you are wearing leather gloves. Place a towel or t-shirt over the bat and pick it up gently, to prevent being bitten. Place the bat on a tree trunk or a wall, at dusk or after dark.
Remember all Tasmanian bats are fully protected species and must not be unnecessarily caught or injured.
Little forest bat
This is the smallest Tasmanian bat. It produces a single young and roosts in tree hollows. The little forest bat has mid to dark grey for on its back and dark grey fur with lighter tips on its belly.
Forearm length: 29-30 mm, Body length: 40-50 mm, Weight: 4-4.5 gm.
Southern forest bat
A small bat, slightly larger than the little forest bat and may be distinguished by reddish brown fur on the back and lighter brown fur on the belly. It used to be called the King River eptesicus.
Forearm length: 32-33 mm, Body length: 45-55 mm, Weight: 5-5.5 gm.
Large forest bat
The large forest bat is the largest of this genus in Tasmania. These bats have dark grey to dark brown fur all over. They are found in all forest types including rainforest and catch insects from the mid canopy to the understorey. They only produce a single young at a time.
Forearm length: 35 mm, Body length: 40-60 mm, Weight: 6 gm.
Chocolate Wattled Bat
Chocolate wattled bat
This species gets its name from its chocolate brown fur. Its lifestyle is similar to the large forest bat. The chocolate wattled bat has a shorter hibernation period than other species.
Forearm length: 40-41 mm, Body length: 50-60 mm, Weight: 9-10 gm.
Goulds wattled bat
This bat has dark brown fur on the back and a black head and shoulders with lighter brown fur on the belly. Usually two young are born, remaining attached during flight. They roost in colonies in hollow trees and feed on insects in the upper canopy.
Forearm length: 46 mm, Body length: 56-75 mm, Weight: 14-15 gm.
Lesser Long-eared Bat
Lesser long-eared bat
The long-eared bats are so called because of their long, strongly ribbed ears (up to 25 mm in length) which can be folded back when at rest. These bats have light grey-brown fur on the back and paler fur below. They fly slowly close to the ground, occassionally alighting on low vegetation. They are found in urban areas.
Forearm length: 39-41 mm, Body length: 40-50 mm, Weight: 8-10 gm.
Tasmanian long-eared bat
This is Tasmania's only endemic bat species. It is larger than the lesser long-eared bat and has ears up to 30 mm in length. This bat has dark grey-brown fur on the back and slightly lighter fur on the belly. It mainly eats non-flying insects which it casptures from the vegetation. It often flies close to the ground searching for food.
Forearm length: 46 mm, Body length: 60-75 mm, Weight: 13 gm.
Eastern false pipistrelle
This is Tasmania's largest bat, with females averaging up to 21 gm. In all Tasmanian bats the female is generally larger than the male. The eastern falsistrelle has reddish brown fur on the back and lighter brown fur on the belly. It used to be named the Tasmanian pipistrelle. It flies quickly, catching mainly beetles from the upper canopy and produces a single young.
Forearm length: 49-50 mm, Body length: 55-70 mm, Weight: 19-21 gm.