Hawkesbury River new home to rare fishing bat

The Large-footed Myotis is a microbat - able to fit into the palm of your hand - and shelters near the river, feeding on fish and insects by diving down over the water and spearing them with its hind feet.

Wildlife ecologist Brad Law of the Department of Primary Industries in Parramatta said if residents were to watch slow-flowing rivers or dams at dusk or just after the sun goes down, they might see fishing bats flying low and zig-zagging over the water.

“It’s the only microbat in Australia that fishes so it’s very unique,” he said, speaking with the Gazette from Western Sydney University’s Hawkesbury Campus during the Australasian Bat Society Conference.

“They have very big feet with quite long claws on the end, and they use these to trawl in the water and stab the fish. They also hunt aquatic invertebrates like water striders, whirligig beetles and also occasionally mosquitos.”

Myotis fishing bats are listed as a vulnerable species in NSW, and they are one of Mr Law’s specialties. While they usually favour fresh water creeks and rivers, they have recently been found in a number of different salt water areas in the Sydney Region including around Sydney Harbour.

“They’re actually hunting using echolocation, which is unique to bats. They can see - so saying ‘as blind as a bat’ is not really true - but they really see the world in sounds. They’re fascinating animals,”  he said.

Their main threats are pollution in fresh waterways, including runoff from fertiliser, industry and heavy metals - the latter of which can accumulate in their bodies because they are at the top of the food chain.

Hawkesbury residents who live along streams and creeks that flow into the river can help protect these fishing bats by protecting and replanting waterside vegetation, which will help provide shelter for these bats and minimise bank erosion.

“They also particularly don’t like lights near the water where they’re feeding, so minimising light pollution near large water bodies [is important],” Mr Law said.

Research into bats is growing at the WSU’s Hawkesbury Institute for the Environment in an area unofficially called the Bat Lab, according to senior lecturer in animal physiological ecology, Dr Chris Turbill.

One of his students, Alice Barratt, has begun a masters of research focussing on the area’s fishing bats, to find out what they are doing here. The project will include gluing tiny radio transmitters to their bodies to measure their temperature in the wild.

“She’s going to use acoustic detectors that can record the echolocation of the bats - whenever they’re active they’re using ultrasonic calls to navigate,” said Dr Turbill.

“And she’ll be looking at seasonal variation in foraging and thermal physiology. It will include diet, and if that changes over the year, and whether they use some form of hibernation in winter time.”

He said other insect-eating bats in the area (there are around ten other species) use small bouts of hibernation called ‘torpor’ to save energy and get by when there’s not much food.

“It’ll be interesting to look at [the fishing bats’] energy budget compared to bats that feed on terrestrial insects,” he said.