Found throughout New South Wales and Queensland, the iconic fruit bat could be in danger. Colin Johnson reports.

Once the sun starts to set in Sydney, birds aren’t the only animals to call the city’s trees their home. From the canopies of Hyde Park to the foliage on Oxford Street scores of fruit bats can be seen rustling in tree leaves, or heard swooping gently through the air and whooping to one another.

Flying fox
Australia’s flying foxes may be in danger. Photo credit: smurfun / Foter / Creative Commons Attribution-ShareAlike 2.0 Generic (CC BY-SA 2.0)

To be specific, those “fruit bats” are actually grey-headed flying foxes, the species of flying fox most common in New South Wales. Colonies of these nocturnal flyers have taken up residence all over the state, but their presence may, in fact, be in considerable danger.

The Queensland government recently released online “damage mitigation permits” to try and combat flying foxes damaging crops. Justin Welbergen, a senior lecturer at the University of Western Sydney, explains that “in Queensland there are these permits given out for shooting a limited number of flying foxes at orchards.”

“This is based on the misguided idea that if you remove the first flying foxes to arrive, then other flying foxes are less likely to show up at your orchard,” Welbergen says.

While this legislation is in effect north of New South Wales, Welbergen described flying fox colonies as “nomadic.” “They go where the food is,” he says.

“The animals can cover hundreds of kilometers a night, and could fly easily all the way from Sydney up to Rockhampton.”

While New South Wales hasn’t created its own “damage mitigation” legislation, flying foxes in Sydney one night could be in Queensland the next, making Queensland’s legislation a potential threat to flying foxes in Sydney as well.

Welbergen is worried about this government policy, “Culling, or roost destruction, doesn’t provide a local solution because new flying foxes will keep coming in until the whole species is depleted.”

One alternative solution to culling or roost destruction is relocation projects, such as that the Royal Botanic Gardens undertook in 2012, widely seen as harmless – and successful.

“Flying foxes would strip foliage from the trees, and over 30 trees in the garden have been killed from this foraging,” says John Martin, an ecologist from the Royal Botanic Garden who helped coordinate this flying fox relocation project.

From June 4-2012, staff at the Botanic Gardens played recorded noises were played before dawn and around sunset for approximately two weeks to disturb the flying foxes roosting in the garden. After the initial two weeks, noise-disturbances were only played before dawn.

Martin spoke of the project’s success, despite mentioning that flying fox numbers in the garden have – since the effort started – been as high as “25,000 sightings in a single day.”

More reassuringly, Martin mentioned that recently “only four [flying foxes] have been spotted in the Garden.”

The number of roosting animals seems to be shrinking as time goes on. The Royal Botanic Garden also lauded the project’s success, but warned that further action and monitoring would be needed to ensure that the flying foxes don’t return to the Garden to roost.

Martin, aware of the necessity of monitoring, describes the monitoring by saying, “noise is used to deter them [the flying foxes], to prevent them from re-roosting.” This is an effort which appears to be a continuation of the initial relocation effort.

Secondly, Martin says the monitoring is done “not just to keep them out, but also related to finding out where they go.”

The monitoring, according to Martin, has found that grey-headed flying foxes “show a total species distribution as far as Melbourne to Bundaberg.”

The Botanic Garden’s project looks to be the most successful, and least harmful to the flying foxes, but other projects – such as the Charters Towers dispersal projects in Queensland – are also working to move flying foxes away from sites they can damage. However, one factor which might explain the Botanic Garden’s success, as Martin explains, is that “grey-headed flying foxes, the species most native to New South Wales, is listed as vulnerable.” Meanwhile “Little Red flying foxes and Black flying foxes, species more native to Queensland, are not.” This listing could be a benefit to the flying foxes of Sydney and New South Wales, as people are less prone to hurt the endangered animal population.

Culling and roost destruction may not be the only threats to flying foxes in New South Wales, however. 
The Northern Star reported in January that approximately 15,000 flying foxes fell from their roosts due to heat exhaustion and dehydration. Any of the flying foxes that didn’t die in the heat were left orphaned as their parents dropped dead to the ground; temperatures were reportedly getting as high as 42 degrees.

According to Welbergen, who primarily studies flying foxes, “up until this last January, the majority of casualties [of the heat] were in New South Wales.”

In April, The Conversation also reported that in Queensland, this summer has seen “one of the most dramatic animal die-offs ever recorded”, with at least 45 500 flying foxes dead in a single day due to the heat. With flying fox colonies being a mobile as they are, colonies in Sydney could potentially fly to their deaths in Queensland’s heat waves if New South Wales’ own heat doesn’t kill them off first.

Welbergen believes that climate change is a major culprit in these flying-fox related deaths, as it is leading to “more extreme temperature events.”

There’s a silver lining: these flying fox deaths may present an unexpected benefit despite all of the damage they do to the species. Welbergen observed that “there are no conservation efforts, except for carer groups” to actively protect the flying foxes, but “when these extreme heat events occur, an army of bat-carers come out the woodwork.” Once the heat starts killing more able-bodied flying foxes, “people go into the colonies to save as many young as they can.”

Even if they can get people motivated to protect them from the heat dangers, Welbergen points out, “flying foxes aren’t special.”

“They’re not unusually susceptible to temperature events. Similar die-offs are happening to koalas, birds, and other parts of biodiversity,” he says.  “The difference is that flying foxes congregate in large colonies and are easier to observe. You don’t have a pile of dead koalas – other animals live more cryptic  lifestyles.”

But flying foxes, despite being in no more danger from these climate extremes than other animals, are still getting people’s attention whether or not they suffer from the heat.

“They’re bats,” says Welbergen. “People have a very visceral reaction to bats. People either love them or hate them. There’s no middle ground.”