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Microbats

Microchiropteran Bats

Bats are an important component of Australia's fauna, constituting about 30% of our native mammal species. All bats are grouped into the Order Chiroptera (Bats). They are divided into two main groups; Megachiropterans (flying foxes/fruit Bats) and Microchiropterans (mainly small insectivorous bats).1

At dusk various species of micro-bats can be observed flying over or around eucalypt canopies or throughout the edges or tracks of bushland areas. These small bats display a rapid, jerky almost haphazard flight while foraging for flying insects from dusk throughout the night. Specialist methods of surveys using electronic call detection recorders and harp traps or mist nests are required to identify what species are found at particular sites.

Conservation Status

Of the 16 threatened microchiropteran bat species in NSW, ten have been recorded within the Gosford, Wyong and Lake Macquarie local government areas as shown in the table below.  All ten species are listed as vulnerable in NSW under the Threatened Species Conservation (TSC) Act, 1995, while two species are also listed as vulnerable under the Commonwealth Environmental Protection and Biodiversity Conservation (EPBC) Act, 1999.

Common Name

Scientific Name

Primary Roost Type

TSC* Act

EPBC** Act

Little Bentwing Bat  Miniopterus australisCave V -
Eastern Bentwing BatMiniopterus schreibersii oceanensis               Cave V -
Large-footed Myotis Myotis adversesCave/ Tree Hollow / Foliage V -
Large-eared Pied Bat         Chalinolobus dwyeriCave/ Tree Hollow V V
Golden-tipped BatKerivoula papuensisTree Hollow V -
Greater Long-eared Bat     Nyctophilus timoriensisTree Hollow V V
Greater Broad-nosed Bat  Scoteanax rueppelliiTree Hollow V -
Eastern Freetail Bat                            Mormopterus norfolkensis Tree Hollow V -
Yellow-bellied Sheathtail BatSaccolaimus flaviventrisTree Hollow V -
Eastern False PipistrelleFalsistrellus tasmaniensisTree Hollow V

Description

Micro-bats are usually small with wingspans of about 25cm. Fur colour is variable and may range from light brown to reddish brown, grey or black. Identifying features include wing shape and length, ears, nose and tail. Identifying the sex of a bat is relatively easy as males bats have an obvious penis.

Little Bentwing bat Greater Broad-nosed BatEastern Bentwing Bat

Diet

  • Micro-bats are mainly insectivorous and take advantage of warm nights to forage when the insect activity is at its peak.  Foraging activities are usually at their highest within the first three hours after dusk. Micro-bats will often forage in sporadic periods throughout the night, often returning to the roost site.
  • Food items may include: moths, beetles, caterpillars, spiders, termites, birds, small mammals, bats, reptiles frogs and even fish (Large-footed Myotis) 2.

Life History & Reproduction

Bats mate in a specific season and in most cases have one pregnancy per year.  Bats generally give birth to only one young, although several species do have twins.  The young are born at the same time of the year to coincide with the best food supply.  Pregnant females often congregate in maternity colonies a few weeks before they give birth.  Some colonies comprise thousands of bats, others include just a few. 

Baby bats feed from the breast and cling to their mothers for the first few days after birth.  After a few days the mother leaves the young at the maternity site while she forages for food.  Once juveniles are older they may accompany the mother to learn how to forage, navigate and find their way back to the roost.  Juvenile females usually become sexually mature during their first year and are ready to breed by the next breeding season.  Males often take an extra year to reach sexual maturity.

Other Characteristic Features

Behaviour: Bats may be seen on dusk or at night foraging under street lights or around spotlights at playing fields. Some micro-bats can be observed foraging in flyways through bushland areas. These flyways are typically an open corridor in the bush such as a fire trail or walking track. Other micro-bats forage for insects throughout the upper tree canopy layers, particularly around flowering eucalypts where insects are attracted to the nectar.   

Scats: The smell of ammonia or presence of Guano at a cave entrance or hollow trees may indicate bat presence. Scats are small (2-4mm) and resemble a mouse scat.

Calls: Micro-bats use echolocation to navigate and to locate insects.  Echolocation calls are high-frequency sound waves made by the bat forcing air through its vocal cords. The calls bounce back from surrounding objects and the bat’s sensitive ears can detect the echoes of their calls.  These calls are mostly inaudible to humans.

Preferred Habitat

Micro-bats inhabit a wide range of habitats within the local area, including vegetation types such as wet and dry sclerophyll forests, melaleuca swamps, rainforests, well timbered valleys, open farm lands, suburban areas and areas surrounding water-bodies.

Where does this Species Roost

Micro-bats are either tree hollow roosting or cave roosting bats, however some species such as the Large-footed Myotis can utilise both tree hollows and caves.  The Eastern Bentwing-bat and Little Bentwing-bat are known to migrate to the same cave each year to give birth and raise young1. The great diversity of roosts used by bats is not random.  Micro-bats choose their roost site for protection against the environment and predators2.

In addition to tree hollows and caves, bats may roost in bird nests, under bark, sheds, hanging clothing, outdoor ornaments, houses or within dense foliage. Despite this bats are typically divided into two main groups based on roosting characteristics.  

Where this Species can be Found

Micro-bats are generally found wherever suitable habitat is present. Micro-bats are widespread throughout the Gosford, Wyong and Lake Macquarie district. These bats are known to occur throughout conservation reserves and inhabit residential areas especially those located near bushlands where they utilise well lit houses, streets and ovals for insects. Examples of areas where these species have been recorded are:

Gosford: Empire Bay, Bensville; MacMasters Beach; Somersby, Peats Ridge.

Wyong: Wadalba Wildlife Corridor, Wadalba; Bruce Crescent, Warnervale; Berkeley Road, Berkeley Vale.

Lake Macquarie: Wallarah National Park, Wallarah; Gradwells Road, Dora Creek; Mt Waring Reserve, Ridge Road, Kilaben Bay.

Where is this Species Habitat Protected?

Gosford: Brisbane Water National Park, Bouddi National Park and Kincumba Mountain Regional Reserve.

Wyong: Wadalba Wildlife Corridor, Olney and Ourimbah State Forest.

Lake Macquarie: Lake Macquarie State Conservation Area and Awaba State Forest.

Threats to Survival

  • Disturbance to colonies, roost sites and maternity caves.
  • Predation by feral cats.
  • Clearing and fragmentation of habitat.
  • Removal of tree hollows.
  • Competition for tree hollows by Common Myna.
  • Use of pesticides.
  • Fire.
  • Reduction in stream water flows quality and quantity.

Management Issues

  • Protection and improvement of roosting habitat, including hollows, caves and dense foliage.
  • Retention or establishment of regional and local corridors for foraging, breeding and roosting in the semi-urban to urban landscape.
  • Erection of roost boxes in suitable habitat.
  • Creekline revegetation to provide suitable foraging habitat near waterways.

Useful Web links

Further Reading

  • Duncan. A, Barry Baker & Montgomery. N (Eds) (1999) The Action Plan for Australian Bats. Natural Heritage Trust
  • Menkhorst .P. (2001) Field Guide to the Mammals of Australia. Oxford Uni Press

Bibliography

  1. Strahan. R. (Ed) (1998), ‘The Mammals of Australia’, Reed Holland Publishers, Carlton, VIC.
  2. Churchill, S. (1998), ‘Australian Bats’, Reed New Holland, Sydney, NSW.