Every evening at dusk, thousands of grey-headed flying foxes fill the skies of Melbourne’s eastern suburbs.
The colony, which can number from 4,000 to 70,000 bats depending on the season, flies out of its roosts in Yarra Bend Park in search of food.
It is a vital quest not only for their survival but also for the regeneration of Australian forests.
“They are the bees of the night,” says Tamsyn Hogarth, owner of the Fly By Night shelter.
“They are looking for the nectar and the flower of our eucalyptus. They are our only long-distance pollinator, so if we lose them, we lose koalas.”
Ms Hogarth runs her shelter from the Dandenong Ranges, with the small group of volunteers working to rescue injured animals and raise abandoned puppies.
Hundreds of flying foxes find their way into their custody each year, mostly after being caught in tree nets, barbed wire and power lines.
“We might do one or two rescues a day,” says Ms Hogarth.
“If the gums don’t bloom, often the animals will go to replace food like nectarines or other things in people’s backyards and then they’ll be cared for.
“One year, I think we had 500 rescues in one month.”
New Victorian tree netting regulations were introduced at the end of 2021, with residents required to use mesh of 5mm by 5mm or less.
But Ms Hogarth says few people are aware of the changes and the flying foxes are suffering.
“Many have to be put down over time due to the severity of the injuries getting worse,” she says.
Although man-made gear poses an ongoing risk, global warming could threaten the very survival of the vulnerable flying fox.
When temperatures rise above 40 degrees, they become stressed and can die in large numbers.
“There are physiological limits in terms of how much energy they use and how much water they need,” says Dr Pia Lentini, senior scientist at the biodiversity research organization, the Arthur Rylah Institute.
“When they are pushed beyond these limits, they become very anxious. They start flapping and licking their wings and slowly descending the trees.
“We know our climate is changing and we’re experiencing more extreme weather events, so we could start to see an increasing number of these heat stress events.”
If flying foxes, which also underpin ecosystems via seed dispersal, become more vulnerable, this could pose a risk to other native flora and fauna.
“Every time we take a species out of the system, the system has to work really hard to bounce back,” says Casey Visintin, an RMIT University researcher and bat expert.
“In some cases, it completely transforms into a state that may or may not be desirable.”
More sprinklers have been installed at Yarra Bend Park and other resting sites across Victoria to cool vulnerable animals.
Friends of Bats and Bushcare are also upgrading Yarra Bend to make it safer for them.
They do regular revegetation work and support Fly By Night in their soft release program, where hand-reared flying foxes are returned to the colony.
The bats are kept in the release cage for about 10 days before slowly returning to the trees, says Megan Davidson, secretary of Friends of Bats and Bushcare.
“We continue to feed them for about six weeks, gradually reducing the amount of food we give them.
“It gives them time to develop their own skills flying with the rest of the wild bats.”
Neither Dr. Davidson nor Ms. Hogarth have formal degrees in veterinary science or conservation, but their passion for flying foxes motivates their volunteer work.
They are also passionate defenders of the Yarra Bend settlement, which has been battered by residents for its noise and strong smell, including calls from former Liberal MP Tim Smith for a 2020 cull.
But Dr. Davidson says it’s important to protect the animals she affectionately calls “pups from heaven.”
“This is an ancient species that has been present on this continent for millions of years,” she says.
“You are looking at a little slice of prehistoric Australia when you are in a bat colony.”
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