Researchers testing cooling method to prevent bat deaths in Campbelltown

An example of roosting flying foxes in Singleton. Picture: NSW Department of Planning, Industry and Environment / Jaime Plaza Van Roon
An example of roosting flying foxes in Singleton. Picture: NSW Department of Planning, Industry and Environment / Jaime Plaza Van Roon

Experts are hard at work on a solution to mass flying fox death during scorching summer heat spells thanks to a first-of-its kind experiment in Campbelltown.

Researchers from Western Sydney University, in collaboration with the Department of Planning, Industry and Environment, World Animal Protection Australia and Campbelltown Council, monitored the temperatures and behaviours of a large grey-headed flying fox camp in Campbelltown during the past summer when exposed to a cooling sprinkler system.

The experiment came after tens of thousands of bats were killed during the high heat stress events in the record-breaking summer of 2019/20.

WSU Associate Professor Justin Welbergen, whose team at the Animal Ecology Lab is analysing the data from the experiment, said there was much insight to be gained from the experiment, even though the past summer was much milder than years gone by.

"We've been very pleased with the data-gathering effort," Associate Professor Welbergen said.

"It clearly hasn't been very hot this summer, which is merciful for the bats, but in terms of our data we didn't get everything that we wanted.

"The plan is to continue next summer.

"We've been able to gather continuous temperature and humidity data across the camp at different heights across the canopy, thermal data from a drone at regular intervals (before and after spraying from the sprinkler), and also behavioural data.

"These data allow us to determine the responses of flying foxes to different temperatures and humidity regimes, and the effects the sprinklers have on them."

DPIE Treatened Species and Conservation manager Linda Bell said the data collection and analysis would have real-world applications.

"Now we can do some analysis on what's worked and what hasn't, whether or not temperatures have been reduced, how the sprinklers have affected humidity, and whether or not the sprinklers are a goer in heat stress events," she said.

"We will be able to see if that's viable, and make decisions based on real data and not just based on an impulse to help vulnerable animals.

"The worst thing we can think of is having them dying in the heat, but the dilemma is we really don't know if what we've been doing up to now is helping them or harming them.

"Other jurisdictions will be interested in trialling this experiment as well. This is the first time a project has included the council, World Animal Protection and WSU."

The sprinkler system within the Campbelltown camp. Picture: Associate Professor Justin Welbergen

The sprinkler system within the Campbelltown camp. Picture: Associate Professor Justin Welbergen

Ms Bell said she was expecting some helpful analysis would be released from the experiment before the start of the next summer.

Associate Professor Welbergen said an important part of his teams' analysis would be determining the effect the sprinkler systems would have on the humidity of the camp.

While the water would definitely cool the temperature, the added moisture in the air could have the effect of creating an artificial tropical climate in the camp, which could potentially reverse any benefits from the reduction in temperatures.

Associate Professor Welbergen said the Campbelltown camp easily housed several thousand flying foxes.

But he said they weren't the same individual bats each day.

"Flying fox camps are part of this vast network through which flying foxes travel, nomadically," he said.

"Flying foxes travel all over the place, all the time - vast distances.

"Sometimes they travel across the entire species range multiple times a year.

"If you were to zoom in on the individual bats at the camp on any given day, 17.5 per cent will not be there the next day. They'll be replaced by flying foxes from elsewhere. There is constant turnover.

"Rather than camps, the sites are better compared to hostels, with an ever-changing clientele."

Associate Professor Welbergen, who is also the head of the Australasian Bat Society said it was extremely important to find ways to ensure the survival of flying foxes, are the animals serve an important purpose in our ecoystem.

"Flying foxes provide key pollination and seed dispersal services, which are very expensive services, entirely for free," he said.

"That is essential for the persistence of Australian forest ecosystems and for regeneration.

"People say about koalas: 'no trees, no me'. But with flying foxes, you could really say: 'no me, no trees'."

Ms Bell and Associate Professor Welbergen thanked the local flying fox carers for their valuable assistance and urged anyone thinking wanting to assist local bat populations to become an accredited carer and receive the appropriate training before engaging with the species.