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We Spent A Night With Tiny Bats In Melbourne

We Spent A Night With Tiny Bats In Melbourne

The most well represented groups of mammals in the Melbourne area are creatures most of us don’t even know exist. LEAH ROBERTSON spends a night with Melbourne’s elusive microbats with Earthwatch.

Backstage at the gardens

The gang sits in a staff mess hall, in the hidden guts of Melbourne’s Royal Botanic Gardens. Kicking around are giant tins of Milo, botanical trade magazines, buckets of ferns in staff showers. Outside – a cluster of other nursery and admin buildings, and various landscaping materials and machinery.

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We enjoy these little glimpses of backstage at the gardens. Most people in our group this evening have environmental science backgrounds. While we get acquainted, they discuss research and share stories of volunteering stints in wildlife reserves. “Sarah the spider-monkey?”, one woman recalls. “Psychotic number, that one.” In lieu of experience, my friend and I grapple for times we’ve come in professional contact with big-name conservationists. Jane Goodall. Alan Rabinowitz. It’s kind of exciting ‘cause we’re staying the night, like school camp. I even had to locate my sleeping bag from somewhere in the depths of storage.

Tiny bats are all around us

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The reason we are here is microbats – to learn about and research them. I didn’t even know they existed, until now. This is normal because our ears can’t hear their calls. They don’t swoop out of shrubs as you walk around Brunswick at night. They don’t eat from your neighbour’s overhanging fig tree. They don’t gaze down at a sweep of the Yarra to navigate home after a night out sniffing for food. Those guys, the ones we know, are megabats. Colloquially, flying foxes or fruit bats.

Microbats are very different. They are about the size of a sparrow and some species are as tiny as moths. They mostly feed on flying insects – mercifully keeping our mozzie population down – though rare species elsewhere fish for wetland bugs, stalk spiders or drink blood. (Not here – no need to worry.) Rather than sight and scent, microbats use incredible powers of echolocation to navigate. Echolocation is like sonar, where the bat emits a very high- pitched call that bounces off objects in its environment, allowing the creature to map its surroundings or locate its dinner. They hide out in little nooks all around us. They are tiny, sharp-toothed little champions, with wings of the most delicate alien fabric and faces like Pixar monsters.

We’re in good hands tonight – our researcher guides are patient, knowledgeable, full of anecdotes. The point of their collective study is to monitor the lives and habits of microbat populations living in and around Melbourne. They’re learning how many bats live here and in which parts of town, and what type of shelter is preferred.

We know that 16 species call greater Melbourne home, but their future isn’t clear. Researchers worry that as the city expands, our human tendencies will impede on their bat needs by, for example, removing dead branches and trees that provide safe little roosting hollows, flooding the night with artificial lighting, or bulldozing insect habitats. Introduced predators are a problem too. Bring in your cat at night, always.

Setting traps for science

Right here in the Botanic Gardens there are four species. Tonight we aim to temporarily capture a few with specially designed “harp traps”, then study and fix identification bands to them to aid research (if not already banded), releasing them by morning.

The thing is, it’s getting dark and the BOM radar is menacing. We need to set up numerous traps before the storm hits. We are novices but with good guidance we give it a go, traversing the garden in teams.

What does a microbat trap look like? Surprisingly big. Like a panel of chain-link fence, but in place of fencing wire, two delicate screens of fishing line are attached to the metal frame – running vertically, like harp strings. A canvas bag is looped around the base.

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The traps capture the bats in flight, without harming them. The fine wire is difficult to detect so sometimes they fly into it, toppling into the bag below, where they are safe and unable to escape.

Uh oh

The storm finds us just as we finish our setup rounds and it rains suddenly and heavily. Violent wind throws a garden umbrella at the surprised guy next to me. Trees fall. This doesn’t bode well for microbat catching – insects will not be flying about and a smart bat won’t be either.

But nonetheless, after sheltering a few hours in our cosy mess hall, we slip head-torches over hooded raincoats and head out into it to check our traps. After the wait it is Christmas morning-esque – despite the night and the rain we can’t see through. And lo, the first trap we visit houses a tiny dark mass within the white canvas that reveals itself to be a female Gould’s wattled bat. She is so small and unfamiliar. We are thrilled. She’s carefully removed and popped into a little cotton bag, carried proudly and protectively by a volunteer.

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We trek the rest of the gardens – through rushing rivulets and past a night wedding in full flight, its guests restricted to a steamed-up plastic marquee, glowing in the gloom – but find no more microbats. On calm nights the researchers might find a dozen, but we will make do with our one.

Finally we meet

Back in our dry abode, our guide tucks the tiny bat’s wings and legs firmly into one hand, her cute/grotesque head protruding. We touch her fur, and gently, her wings, and are in awe. The researchers produce a device that “translates’”echolocation ultrasound signals into frequencies audible to human ears and, when switched on, it reveals that our friend is chirping and chattering like the strangest bird.

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Our little Gould’s, after examination, is determined to be around one-year-old. She has never given birth, and has tiny nipples in her armpits. When she does reproduce, her young will latch onto these as she flies ­­– baby microbats hitching underarm rides. She weighs 13.8 grams. We fix a tiny, barely perceptible band to her arm.

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We sleep after this, drifting off on our stretcher beds to the odd sound of transmitted microbat chatter. Overnight, more soggy trap checks are completed (to no avail), and our girl is released from her warm cotton bag, flying reluctantly home to her roost.

In the morning we eat eggs, then step around storm-felled trees on our way to dismantle the harp traps. A still dawn in the gardens, with the new knowledge of all these little guys hanging out in nooks around us – out of sight, and making a racket we can’t detect. Pretty great.

(Lead image is supplied. All other images are author’s own.)

The writer was a guest of Earthwatch’s Scientist For A Day: Melbourne Microbats expedition. You can use your Qantas points for a range of sustainable activities. Learn more here


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