In the last few weeks, extreme heat has affected our flying-foxes. This and the bushfires currently ravaging eastern Australia are all related – with a warming climate, heatwaves are becoming more frequent and severe, which is exacerbating the bushfires, and also directly causing casualties in flying-foxes.
We’ve mentioned in previous posts that before Christmas, extreme conditions in South Australia killed over 10,000 flying-foxes in a couple of days, and 3-4,000 animals in Victoria.
This last week, we’ve had extreme temperatures in the Sydney and Hunter regions, so much so that on one day Penrith in western Sydney was the hottest place on the planet at 48.9 C. https://www.theguardian.com/…/australian-weather-canberra-a…
This burst of extreme temperature has resulted in mass fatalities of flying-foxes in many camps in the area, made worse by the fact that the flying-foxes are in big numbers in this region, as south of Sydney is basically a burnt wasteland… and that many of the animals are probably weakened by having to fly long distances to escape the fires.
Even Sydney Bats’ home camp has had mass fatalities. We don’t usually experience this, as the valley the camp is in is heavily vegetated and protected – but the storm that went through the local area in November last year caused damage to the vegetation in the valley, leaving it more exposed https://www.theguardian.com/…/sydney-storm-power-cut-to-470… – and we currently have double the usual number of bats resident for this time of year, a result of bats trying to escape the fires…
It’s quite common for people to claim that “it’s just nature”, or “survival of the fittest”, or “we’ve always had heatwaves”. But this isn’t normal. Yes, in Australia there’s always been heatwaves, and droughts, and fires. But they are becoming more frequent, and more severe. Which is in line with predictions made by climate scientists. For our wildlife, this is hitting combined with decreasing habitat, and being forced into less suitable and less protective environments.
Wildlife rescue groups have been doing what they can, but their ability is limited in these extreme conditions. Like the Rural Fire Services who are trying to actively fight the bushfires, there’s not enough resources available to do the job effectively – so compromises have to be made…
There’s some good links available which show the scale of the devastation – I’m deliberately just going to link to them here rather than share them, with the caveat that yes there’s good information but it’s distressing…
Flying foxes are dying en masse in Australia’s
extreme heat
In three days before Christmas, thousands of the
mammals died in 110-degree heat in one Melbourne park.
Dozens of panting, suffocating
gray-headed flying foxes clump together in an attempt to survive 110-degree
heat in Yarra Bend Park, outside of Melbourne, in late December. Some 4,500
foxes, including many of these seen here, died over three days in the park.
The 30,000 gray-headed flying
foxes in Yarra Bend Park, just outside the heart of Melbourne, Australia, were
having a fairly normal early spring.
In September and
October—springtime in Australia and prime birthing season for the 11-inch long
megabats—many of the flying foxes had returned to the park from their winter
migration
up the coast. Females were
birthing pups as normal, says biologist Stephen Brend, who is in charge of
monitoring gray-headed flying foxes in Victoria province, including at Yarra
Bend Park, which is home to a significant colony of the bats. All was routine.
“And then the horror started,”
Brend says. “It got too hot, too quickly.”
Incapable of surviving the
extreme, relentless heat that gripped Melbourne in December, the flying foxes
were dying. Across three days just before Christmas, when temperatues exceeded
110 degrees Fahrenehit, 4,500 of the park’s gray-headed flying foxes
perished—15 percent of the colony’s population.
The tragedy for flying foxes in the park echoes scenes of wildlife suffering across the country and puts a spotlight on the perils of extreme heat, which for some species can be just as deadly as fire. Great and small, fast and slow, Australia’s endemic animals are falling victim to the heatwaves and fires that are ravaging the country at an unprecedented scale. It’s the hottest and driest summer in Australia in recorded history. As the planet warms, large-scale fires are becoming more frequent, and bushfire seasons are getting longer.
For gray-headed flying foxes, which are classified as vulnerable to extinction by the International Union for the Conservation of Nature, the Yarra Bend event is not isolated. “The colony in Adelaide suffered even worse,” says Brend. Several thousand flying fox babies died there from extreme heat between November and January, says Justin Welbergen, associate professor of animal ecology at Western Sydney University and president of the Australasian Bat Society. On January 4, many thousands of flying fox babies died across multiple roosts in and around the Sydney region in New South Wales, where the temperature reached a record-breaking 121 degrees Fahrenheit. Welbergen’s team, which monitors flying fox heat stress conditions, is calculating a final death toll.
This summer’s extreme heat and
extreme fires, which have imperiled Australia’s entire eastern coast—prime
flying-fox habitat—“risk wiping out the 2019 generation” of newborn bats, Brend
says. Some 80 percent of flying fox pups are born in October. They were young
and vulnerable when heat waves and wildfires broke out late last year.
Hour by hour in extreme heat
A day in the life of a flying
fox in a heatwave is unforgiving. By 5:30 a.m., as dawn breaks, the bats have
returned to their trees after spending the night feeding on nectar and fruit.
By 8 a.m., Brend says, it’s getting hot in their roosts. The bats fan their
wings to keep cool, but they can only do it for so long before they start to
get tired, he says. By noon, they’re getting exhausted, and temperatures
continue to climb. The bats start to pant, which accelerates dehydration.
At that point, they could fly
into the river to get a drink (the Yarra River runs through the middle of the
640-acre park), “but it’s like us running to the shop in the middle of a heat
wave,” Brend says. Flying takes energy, and when they’re exhausted and
dehydrated, they’ll simply stay put.
Distressed and starting to
panic, the bats try to find a cool spot. Mothers will deposit their babies on
branches and separate, Brend says, searching for a tree trunk that might be
cooler. The bats follow each other—spotting one on a trunk seems to signal to
the rest that it’s a refuge. They start to clump together. “It’s like a
football scrum of bats,” Brend says. “To the observer, it looks mindless.” The
ones who got there first are now surrounded and smothered by dozens of others.
“At that point in time
everything has gone wrong,” Brend says. That’s when his team, made up of park
staff and volunteers, will step in to try to break up the clumps by spraying
them with water, which cools them down and slakes their thirst.
Tragedy on the trees
On December 20th, at the
height of the three-day heat event that killed 4,500 flying foxes, “it never
got cool,” Brend says. At 9 p.m., the team was out spraying. But it was pitch
black, tree limbs were falling, and there are venomous snakes in the brush. “We
had to call it off. We couldn’t see. It was 38 degrees [100 degrees
Fahrenheit]. It was deeply distressing,” he says. “It was carnage.”
“One falls, and the rest
cascade on the ground, crushing and suffocating each other. Dozens if not
hundreds of dead or dying bats are at the bottom of the tree,” says
Melbourne-based photojournalist Douglas Gimesy, who documented the December
rescue efforts. “You’re looking down at them and they’re looking up at you
gasping. They’re smothering and heating up. Volunteers will go in and separate
out bodies and find some that are still alive. But you’ve got 20 to 30 rescuers
and 4,500 bats. It’s like a war zone. It’s sad and distressing and
heartbreaking, and you know it will happen again and again and again.”
“Some we get to in time,” says Tamsyn Hogarth, one of the rescuers. “Others die in your hand.” By the third day, on December 20th, the air was thick with “the smell of death,” she says. Hogarth runs Fly By Night, a wildlife shelter in Melbourne dedicated to rescuing, rehabilitating, and releasing gray-headed flying foxes. She and other volunteers rescued 255 babies during the extreme heat events in December in Yarra Bend Park. Two dozen volunteers across Victoria province are currently caring for the bats, which range in age from two to 12 weeks old.
Heatwave deaths are normal for the bats—but this is
different.
Hot days causing bat deaths
are normal in Yarra Bend Park. “We’re always worried about heat events. You’re
not going to get through summer without having really hot days,” says Brend.
Last summer, for example, a
few hundred bats died, he says.
One study found that between 1994 and 2007, approximately 30,000 gray-headed flying foxes died in extreme heat events in Australia.
But the timing of this year’s
extreme heat—right after birthing season—contributed to unusually high
mortality. Because the young were still nursing, their mothers’ energy levels
were depleted, and all of them—parents and new babies—are more vulnerable,
Brend says. The first weekend in December was extremely hot, and it was
followed by a succession of hot days all month, culminating in the three-day
death event, reaching a peak of 110 degrees Fahrenheit in Yarra Bend on
December 20.
“It’s emotional and
frightening for the species. And this is happening across their entire range,”
Brend says. While Yarra Bend Park hasn’t been hit by fires, much of the flying
foxes’ habitat lies directly in the fire zones along Australia’s east coast.
The bats are nomadic. Much of
their range is currently in the fire zones. Many travel north in winter,
roosting in forests along the coast, which they may find scorched. The
“bushfires have destroyed essential foraging resources on unprecedented
scales,” says Welbergen. “There is no refuge for them,” says Brend. “It’s not
like it’s bad in Melbourne but will be OK in northern New South Wales—it’s not
OK anywhere.”
“That can’t go on for too many
cycles before the population declines,” Brend says. “I don’t want to be
alarmist or dramatic—there are still thousands of these bats—but there’s no
reason to be confident anymore.”
“Our worry is we’ll have the
new passenger pigeon,” he says, referring to what was once the most abundant
bird in North America before being hunted to extinction in the 19th century.
‘Bats need the forest and the forest needs the bats’
Flying foxes play a vital role
in the forest. “Their ecological role is as big, nocturnal bees,” Brend says.
They carry seeds and pollinate trees, gardening the forest by night. “Bats need
the forest and the forest needs the bats,” says Brend.
And it’s still the middle of
summer in Australia. “We’ll battle on for our upside down friends,” says
Lawrence Pope, a rescuer caring for five orphaned baby bats at home, “but
things look very grim.”
“In this horror year, all species are suffering. It’s
really frightening,” Brend says. “We’re hot, and they’re hot, and it’s a
nightmare.”