Little forest bats: Earth’s tiniest heroes

Name(s): Little forest bat (Vespadelus vulturnus)

Size: Weight: 3-6g. Wingspan: 15cm.

Diet: Little forest bats love eating mosquitos, including the species responsible for the Ross River Virus. That means if you’re not a big fan of mosquitos, little forest bats are your new best friend!

Habitat/range: Coastal and inland regions of south-eastern Australia, including Tasmania.

Conservation status: Least concern, but threatened by the loss of hollow-bearing tree roosts.

Superpower: Small but mighty! These tiny bats punch above their weight when it comes to pest control, eating hundreds of insects every night, catching prey in mid-air, and using their tail to scoop insects into their mouth while flying!

Photo of a little forest bat on a tree branch
Little Forest Bat, Blue Mountains. Credit: Chris Lindorff, (CC BY)

Little forest bats are one of Australia’s smallest mammals, usually weighing around 3 to 6 grams as an adult – the weight of a five cent coin or US dime! True to their name, these bats prefer the lush environment of forests to caves, and devour hundreds of mosquitos, moths, and other pest insects every night. By emitting ultrasonic calls and listening to the echoes bouncing back, they create a detailed mental map of their surroundings, allowing them to detect obstacles and insect prey. Their echolocation is too high pitched for humans to hear, so they tend to “fly under the radar”, but if you happen to be near a forest in south-eastern Australia, chances are you’ll find these bats fluttering overhead! 

Because insectivorous bats are smaller and quieter than their fruit eating cousins, many Aussies have never heard of the little forest bat. But they’re the unsung heroes of our ecosystems, keeping bug populations under control.

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If you’re lucky enough to spot one, you’ll notice forest bats show off incredible aerial acrobatics that would make any fighter pilot jealous. They effortlessly navigate through dense foliage, making tight turns and dives with remarkable precision while chasing food.  

Little forest bats are the smallest of the forest bat species, which have overlapping ranges, making them difficult to identify at times. Strangely enough, one of the ways researchers determine the difference between species of forest bats is by checking their penis! It may be a bit weird, but since forest bats share a lot of similarities, researchers use clues like echolocation calls, arm length, weight and even penis shape to determine the species.

A little forest bat held in gloved hands
Little forest bat. Credit: Fiona Murdoch, Mallee Conservation

Male little forest bats are bachelors and prefer to live alone, but the females tend to roost together in small groups from 20 to 120 individuals. Every year in late spring, little forest bat ladies get together with a group of their best gal-pals to raise their babies together in a maternity roost. They give birth to a tiny hairless pup that weighs about 25% of their body weight (that’s like a human having a 14-kilo baby!) These hard-working single mothers nurse their babies for around seven weeks until they learn to fly and catch bugs on their own. Like all bats, they make great mums, and will even carry their bub while flying if they need to change roost sites.     

A little forest bat held in a gloved hand
This little forest bat was rescued as an orphan, hand raised by an expert carer, and released in 2019. Researchers discovered him living his best life as a healthy adult during a catch and release survey, almost one year later! Credit: Lindy Lumsden

Little forest bats are facing their own housing crisis, especially near human cities where large old trees are scarce and competition for tree hollows is high! Like 42% of Australia’s mammal species, little forest bats primarily live in hollows, which makes them highly dependent on old growth forests. Some resourceful little forest bats have gotten creative and figured out that patio umbrellas and roofs make pretty good roost sites. This impressive adaptability allows them to persist in suburban areas, but unfortunately, living close to humans has some downsides for little forest bats; cat attacks are one of the leading causes of injury and mortality. Little forest bats remain adorable and adaptable in the face of adversity, but they need all the help they can get to survive in the face of habitat loss and introduced predators. These tiny mosquito-eating marvels deserve your vote for Australian Mammal of the Year!

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