As the sun finally dips below the horizon, the small crowd that had gathered on the hill to see Melbourne’s skyline silhouetted against a glorious summer sunset slowly starts to drift away. If only they had waited another 15 minutes they would have witnessed something much more spectacular, something much more memorable and unique than just another sunset over a big city…
Instead they would have witnessed the daily exodus of up to 50,000 grey-headed flying foxes making their way from their urban sanctuary to the suburbs of Melbourne and beyond. The Park Ranger responsible for their Melbourne home at Yarra Bend Park, zoologist Stephen Brend says: “I don’t think most people appreciate how lucky we are to have this right on our doorstep, just 5km from the city. What an incredible spectacle it is to witness flying mammals, with wingspans of over a metre, crossing a major city at night. I’ve worked all over the world, and seen the animal migrations in Africa, but this fly-out is certainly one of my favourite wildlife experiences, and so easily accessible to everyone to watch”.
But why do these ‘megabats’ – so named because they belong to a family that includes the largest bat species – fly out at night? Where are they going? Well, like many Melbournians, they are heading out for dinner, but in this case hoping to feed on the pollen and nectar of flowering eucalypts and native hardwoods (such as banksias and melaleucas), as well as native rainforest fruits. Of course you can’t always get the meal you’re looking for. Sadly these trees and plants are not as plentiful as they used to be, and so the flying foxes will also turn to eating the more ‘exotic’ introduced fruits commonly found in gardens. But whether eating native or exotic food, it’s when they drop in for dinner that most people get their first close-up encounter with these amazing flying mammals.
Also commonly known as a fruit bat, the grey-headed flying fox (Pteropus poliocephalus) is one of four mainland species of flying foxes found in Australia, along with the black flying fox (Pteropus alecto), the spectacled flying fox (Pteropus conspicillatus), and the little red flying fox (Pteropus scapulatus). Flying foxes differ markedly to the smaller bat species. As Dr Justin Welbergen, President of the Australasian Bat Society explains: “most smaller bats tend to roost in dark places like caves, mines, tree hollows and under bark, and rely on echolocation to navigate and find food (usually insects). Many don’t travel long distances in search of food but rather hibernate when supplies are low. Flying-foxes, however, roost in amongst the branches of tall trees, possess keen eyesight and a powerful sense of smell, and travel epic distances in search of ephemeral sources of nectar, pollen and fruit”.
Highly social and intelligent mammals, grey-headed flying foxes can live for up to 20 years in the wild and typically give birth to just one pup per year, normally between September and December. Being highly social means they also tend to roost in large groups. These gatherings are not only important for social interactions, but are also a place for them to rest and a provide refuge during the significant phases of their annual life-cycle, such as mating, giving birth and raising their young. Although generally used intermittently, some flying-fox camps have now been established for more than 100 years – longer than some Australian cities.
Whilst an incredible spectacle to watch, the daily nocturnal excursions of grey-headed flying foxes also play a vital role in the health of native forests. They help disperse pollen and seeds, and in doing so, contribute to the reproductive and evolutionary processes of forest communities. In fact, flying foxes are Australia’s most effective long-distance native pollinators and seed dispersers, at least as important as the other well-known pollinators such as birds and bees, who are often given all the credit for this role. Grey-headed flying foxes travel, on average, around 20km a night before returning home. But the spread of pollen and seeds isn’t only limited to the 20km radius around an established camp. The trees that flying foxes rely on for food tend to flower at different times in different parts of the Australian landscape, so local nectar and pollen supplies are generally not stable enough for many bats to base themselves in a single place for the entire year.
Instead, as winter approaches in Victoria, many will leave the safety of their Melbourne camp and move up the east coast in search of large flowering events to help them get through the lean colder months. During this time the Melbourne population that can swell to nearly 50,000 over summer, will drop to between just 2,000 and 5,000. As Dr Welbergen puts it: “camps are more like backpacker hostels than stable households, housing a constantly changing clientele that comes to visit local attractions. Camps are connected into large networks through which flying foxes move in response to changes in local food resources.” Indeed, grey-headed flying foxes have been recorded travelling between Melbourne and Sydney in just two days – that’s 880km. Dr Anja Divljan from the Australian Museum says “Grey headed flying foxes are vital for the health of our ecosystems. Thousands of pollen grains collect on their fur and many small seeds collect in their gut. Coupled with their ability to fly long distances each night, this means they provide a great mechanism for cross-pollinating plants and dispersing seeds over large areas – they really are the great night gardeners of our ecosystem”.
Leaving the safety of their homes in an urban environment in search for food can be extremely dangerous. Natural predators include large birds of prey (e.g. Powerful Owl), large snakes and goannas, but becoming entangled in fruit tree netting and barbed wire, as well as being electrocuted on power lines can take a terrible toll. No one appreciates the impact that these types of human obstacles can have more than Bev Brown. Recently awarded an Order of Australia Medal for her decades of work rescuing and caring for urban Grey-headed flying-foxes, Bev says “I don’t think people realise how devastating power lines, or inappropriate fruit tree netting, or barbed wire can be to these mammals. I have rescued over 300 grey-headed flying foxes in the last 10 years, and I’ll never get used to seeing them tear their wings as they desperately try to untangle themselves from someone’s backyard fruit tree netting, or as they hopelessly try and chew their way through barbed wire. I’ve even seen an entangled mum try to chew her wing off in a desperate attempt to escape and get back to her pup in the camp. It’s just heart breaking, and what’s really frustrating, is that much of this trauma is preventable. If people just did a few simple things like use appropriate fruit tree netting or paint the top line of any barbed wire in a bright colour so they can see it, it would make a huge difference”.
Barbed wire, fruit tree netting and power lines are not the only threats to grey-headed flying foxes. Disturbance, habitat destruction, and legal shooting in commercial fruit orchards have all taken their toll on the population. Perhaps worst of all, flying foxes can experience fatal heat stress when temperatures exceed 42°C, with some events causing mass deaths on a biblical scale. Over two days in November 2018, a record-breaking heatwave in Northern Queensland saw the mercury rise to 42.6°C, killing at least 23,000 spectacled flying foxes – estimated to be a full third of the Australian population. The same event also wiped out around 10,000 black flying foxes. With climate change projections forecasting higher temperatures and an increased likelihood of heatwaves, flying foxes are going to need all the help they can get.
Wildlife carer Julie Malherbe looks after three recently orphaned pups in her home, whilst simultaneously taking calls on the phone to manage the next wildlife rescue (below left). Rescued bats need to be hand-fed fruit, and many are bottle-feds up to six times a day, they also need their wings moisturising with baby lotion and are kept stimulated with kids’ toys. In the wild, the mother bats would lick them clean, but Julie draws the line at that!
Some rescued bats that are cared for in private homes can’t be released immediately back into the wild. They need a half way home, where they can first get used to being in the open, and with other bats, while still having the safety of a shelter and food to come back to. This process is known as a ‘soft release’. During the soft release process, bats are provided with food and care.
Time to Fly!
Rescued grey-headed flying foxes are released back into the wild at the Melbourne camp after months of home care by Graeme and Treycee, volunteer bat rescuers and caretakers. After two months of care, a rescued and rehabilitated grey headed flying-fox, released just seconds earlier, takes to the skies to head back home to his colony. Even after rehabilitation and release, bat carers work hard to boost their former patients’ chances of survival, carrying out weekly habitat maintenance patrols and planting over 1000 trees in the Yarra Bend Park every year.
Another challenge faced by grey headed flying foxes is their unjustified reputation. They’re maligned as fruit thieves and disease carriers and – like all bats – they’re stereotyped as being sinister and ghoulish, rather than the intelligent, highly social, and indeed affectionate creatures they really are. While it’s true that flying foxes have been known to cause damage to commercial crops and orchards (and they can also roost in large numbers in public gardens, sparking concerns about noise, droppings and power outages), it’s important to remember that they are running out of space, and simply looking for homes and food. They also provide a vital service, keeping the ecosystem healthy by dispersing seeds and pollinating native plants.
The belief that they’re riddled with disease is another falsehood. Flying foxes may be hosts for Hendra virus and Australian bat lyssavirus, but human transmission is rare. In the past 25 years, no more than seven people have died after being infected with one of these diseases (and none directly from bat bites or scratches). Statistically, you’re more likely to get sick from a dog bite. The risk of disease can also be greatly reduced by not touching flying foxes. For some people, the animosity towards the bats is more personal in nature. To prevent their backyard trees being stripped of fruit, they use unsuitable netting. The risk of injury to bats, birds and possums would be greatly reduced with simple changes, such as using a smaller weave and
making all netting white, and thus more visible to wildlife. Indeed, in September 2019, the Victorian Government drafted legislation that would restrict the type of netting used to protect household fruit trees – an Australian first. Under the new law, anyone found selling netting that doesn’t meet these regulations would face a penalty.
“There is no justifiable reason that netting which causes horrific injuries to wildlife should not be banned,” says photographer Doug Gimesy, “especially given that there are equally effective and safer alternatives available”. Stephen Brend, Bat Ranger for Parks Victoria, hopes that public education can help dispel some of the misconceptions surrounding flying foxes, and promote a more wholesome attitude: “more and more people are coming to appreciate these amazing animals, and how lucky we are to share our city with them,” he says.
Far from being flying vermin, grey-headed flying foxes are a vital part of the Australian landscape, and their contribution to native flora deserves to be recognised.
Words and photos: (c) Douglas Gimesy / naturepl.com