SWIFFT - State Wide Integrated Flora and Fauna Teams

SWIFFT - State Wide Integrated Flora and Fauna Teams
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Golden Plains Shire
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Insectivorous bats of Victoria

common bent wing bat

Southern Bent-wing Bat - Critically endangered

Key points

Insectivorous bats consume at least half their body weight in insects per night when feeding. They are one of nature’s natural pest controllers and can play an important role in reducing agricultural pests.

 

The loss of habitat, particularly big old tree and loss of tree hollows is a major threat to insectivorous bats – the less big old trees the less bats.

 

Insectivorous bats enter state of torpor (May – September), disturbance to bats in torpor can have a significant impact on their ability to survive.

 

The Southern Bent-wing Bat population at Naracoorte has suffered a 67% reduction over three generations. Insecticides, drought and land use change all being contributing factors. 

 

Thermal imaging cameras, laser beam technology and radar tracking systems are now being used to monitor bats.

 

There is high variability in cave use by bats which means non-intrusive monitoring must be carried out regularly throughout the year, over multiple years.

 

It has been difficult to determine the impact of windfarms on Southern Bent-wing Bats because there have been limited requirements on operators to search for mortalities and report findings.

 

Chocolate Wattle Bat

Chocolate Wattled Bat

Insectivirous bats of Victoria

These are the most abundant species of bats. There are 16 species in Victoria and south-eastern South Australia. Insectivorous bats are generally tiny; they are sometimes referred to as microbats. People are not usually aware of their presence due to their nocturnal behaviour and their ultrasonic calls which are inaudible to the human ear.

Species

Scientific name

Status Victoria

Status South Aust.

 Gould’s Wattled Bat

Chalinolobus gouldii

 

 

 Chocolate Wattled   Bat

Chalinolobus morio

 

 

 Eastern False   Pipistrelle

Falsistrellus tasmaniensis

 

Endangered

 Southern Bent-wing   Bat

Miniopterus schreibersii bassanii

Critically Endangered

Endangered

 Eastern Bent-wing   Bat

Miniopterus schreibersii oceanensis

Vulnerable

 

 Large-footed Myotis

Myotis macropus

 

Endangered

 Lesser Long-eared   Bat

Nyctophilus geoffroyi

 

 

 Gould’s Long-eared   Bat

Nyctophilus gouldi

 

Endangered

 Inland Broad-nosed   Bat

Scotorepens balstoni

 

 

 Large Forest Bat

Vespadelus darlingtoni

 

 

 Southern Forest Bat

Vespadelus regulus

 

 

 Little Forest Bat

Vespadelus vulturnus

 

 

 Yellow-bellied   Sheathtail  Bat

Saccolaimus flaviventris

Data Deficient

Rare

 Southern Freetail   Bat

Mormopterus  sp. (sp. 4)

 

 

 Eastern Freetail Bat

Mormopterus  sp. (sp. 2)

 

 

 White-striped   Freetail Bat

Tadarida australis

 

 

Breeding time  - October to December

  • Gould's Long-eared Bat Nyctophilus gouldi; giving birth to one or two young (Nov-Dec).
  • Gould's Wattle Bat Chalinolobus gouldii; start of birthing to two young (Nov-Dec).
  • Inland Broad-nosed Bat Scotorepens balstoni; giving birth to one or two young (Oct-Nov).
  • Lesser Long-eared Bat Nyctophilus geoffroyi; giving birth to one or two young (Oct-Nov).
  • Little Forest Bat Vespadelus vulturnus; giving birth to one young (Nov-Dec).
  • Southern Forest Bat Vespadelus regulus; giving birth to one young (Nov-Dec).

Bats are a farmer’s friend

Bats consume at least half their body weight in insects per night when feeding. They are one of nature’s natural pest controllers and have been recorded feeding on insect pests to primary producers.  The composition of insects consumed by bats varies between species. 

The Little Forest Bat consumes bugs, beetles, moths, ants, flies and mosquitoes. The Chocolate Wattled Bat has been recorded feeding almost entirely on moths. The Southern Freetail Bat has been recorded feeding on bugs, ants, flies and mosquitoes. The Southern Myotis feeds exclusively over water on insects and small fish.

little forest bat

The Little Forest Bat is a species that would most likely be flying over peoples homes in the summer months feeding on insects such as mosquitoes.

Roosting

Most species roost in tree hollows; some are specialists requiring dead trees, others only roost in live trees containing spouts. The female Lesser Long-eared Bat only roots in large cracks in dead trees to give birth. The Southern Bent-wing Bat only roosts in caves and although they are found across south-west Victoria and south-eastern South Australia there is only one cave in Victoria and one in South Australia where they go to give birth.

Old paddock trees provide valuable habitat for many species of bats, some species will use cracks in the tree or under the bark whilst other species will use hollows or dead spouts. Some species will even use cracks in old fence posts where there is a shortage of natural roosting habitat.

Buildings are sometimes used by insectivorous bats for roosting;. They do not cause structural problems and do not eat through wiring etc. Generally their presence in eating insects outweighs any problems.

Don't disturb bats

Disturbance to bats in overwintering caves needs to be avoided. There are cases where bats have fallen to their death because they try to fly in a state of torpor. Long term impacts are not readily seen. Each time a bat comes out of torpor they use up valuable fat reserves. If there are multiple disturbances there is a high probability they will not have enough energy to feed in the spring and starve to death.

Disturbance during summer has been identified as a problem in some areas where tourists and holidaymakers enter caves, which is likely to result in bats fleeing the cave in daylight and using valuable energy reserves and making them more prone to predators. Repeated disturbance can result in abandonment of the cave. Disturbance has been identified as an issue in some areas along the coastline where otherwise perfectly good caves have been rendered unsuitable, sometimes forcing bats to use much smaller caves and crevices that are marginal habitat, which can only support low numbers.

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