Backyard guardians: Bats
By Dr Lisa Cawthen, environmental consultant and educator
As the sun sets over Lutruwita/Tasmania and the evening chorus fades, a hidden shift begins. From tree hollows and rooftops, tiny winged warriors take flight – our microbats. These backyard superheroes spend the night devouring hundreds of insects, helping to keep our ecosystems in balance.
Often misunderstood, bats are far from ‘blind’. They can see just fine – but their real superpower is echolocation, a remarkable skill that lets them hunt and navigate in total darkness with pinpoint precision. So next time you see a flicker in the night sky, remember: the bats are out, hard at work keeping your backyard healthy and perhaps catching 1,000 mosquitoes each night. All superheroes need a superpower, right? And echolocation is theirs.
Dr Lisa Cawthen with a bat detector. Photo provided by Lisa.
Meet the Tasmanian bat pack
Lutruwita/Tasmania is home to at least eight species of microbat. These range from the pint-sized little forest bat – weighing just five grams, or about the weight of two jellybeans – to the white-striped freetail bat, a true tank of the skies at around 40 grams, about the weight of a chook egg.
Not long ago, we thought there were only eight bat species in Tasmania, but since 2010, the white-striped freetail bat has been regularly spotted here. Could this be our first mammalian climate-change refugee from mainland Australia?
Tasmania’s microbat family includes:
- Little forest bat, Vespadelus vulturnus
- Southern forest bat, Vespadelus regulus
- Large forest bat, Vespadelus darlingtoni
- Chocolate wattled bat, Chalinolobus morio
- Lesser long-eared bat, Nyctophilus geoffroyi
- Tasmanian long-eared bat (endemic), Nyctophilus sherrini
- Eastern false pipistrelle, Falsistrellus tasmaniensis
Each species has its own distinct diet and habits. While suitable habitat be found across much of Tasmania, some species, like the Tasmanian long-eared bat, are rarely seen – and we still know very little about how their populations are faring in our ever-changing world.
Hotspots for bat diversity include the forests around Fern Tree, Pirates Bay, Mole Creek, Liffey, and Coles Bay. One of the best spots to experience bats in action is the Pipeline Track at Fern Tree. On warm summer nights, this trail becomes a highway for hungry bats, darting and weaving as they feast on insects hovering above the track.
Chocolate-wattled bat. Photo by Anthony Mould
Not just cave dwellers
Contrary to popular myths, the bats of Tasmania don’t generally roost in caves. Most rely on tree hollows, especially during the spring breeding season.
Each spring, female bats form maternity colonies, gathering in cosy tree hollows to give birth and raise their pups. The males are usually kicked out of the hollows until pups learn to fly. These hollows aren’t necessarily small either – some colonies are known to have hundreds (possibly thousands) of bat mummas and their young, requiring large hollows.
Bat mummas are also clever; they switch hollows every few days to avoid parasites and predators. But here’s the challenge: each colony needs 10 to 12 different hollows per season. That’s a lot of real estate in forests where tree hollows can take hundreds of years to form.
Lesser long-eared bat maternity colony. Photo by Lisa Cawthen.
A real estate crisis in the canopy
Like many of us humans, bats are facing a housing crisis. Many species in Tasmania rely on tree hollows to survive and raise young. But with fewer old trees with hollows remaining, many taken over by swarming honeybees. Competition for these vital shelters is intense. Without enough hollows, where will our backyard guardians go?
Bat-tastic ways to help
The good news? Everyone can help. Even if you are not a steward of hollow-bearing trees, bats can travel several kilometres each night between where they roost, forage, and drink. Recently, I used a bat detector in my own backyard in South Hobart and was amazed to discover at least six different species zipping around above me, despite having no hollow-bearing trees in my own backyard.
Here are some simple ways you can support our backyard guardians:
Protect their homes. Leave hollow-bearing trees standing where possible. If one must be removed, try to salvage and re-establish the hollow. Plant tree species like eucalypts that will form hollows over time. Remember, micro bats can live for decades, so they need long-term solutions!
Install a bat box. While nothing beats a natural hollow, a well-designed bat box can provide temporary shelter and even breeding habitat. Not all species use them, but it’s a great start. Visit www.ausbats.org.au for designs and setup tips.
Build a bat buffet. Plant night-blooming fragrant flowers to attract insects, especially native plants. Leave log piles and leaves to create habitat for bugs, build insect hotels and consider creating an open compost heap. Add a pond or water feature to help quench bat thirst and boost insect diversity at the same time.
Protect the night. Light pollution can disturb a bat’s nightly activity and reduce the amount of habitat available for roosting, foraging and commuting. Turn off unnecessary outdoor lights and audit your home’s lighting to reduce the light pollution in your own area. Visit www.darkskytasmania.org for tips on preserving our night skies.
Keep your cat contained. Cats pose a significant threat to bats, especially during the day when bats are snoozing. Keep your feline friends indoors or in a secure “catio” to protect both your cat and our bats.
Become a bat detective (chiropterologist). Join a citizen science project like CallTrackers, and discover what species are flying through your local skies. Or get your own bat detector; it’s fun, fascinating, and educational. Faunatech is a great place to learn more.
Bats are important to Tasmania’s ecosystems, and they need our help to keep doing their incredible night-time jobs. So next time you hear a flutter after dark, take a moment to appreciate these tiny, tireless superheroes and consider giving them a helping hand.
Banner: Eastern false pipistrelle by Lisa Cawthen.