There are lots of ways for a grey-headed flying-fox to get into trouble. Poor quality netting on fruit trees is perilous, hot and dry days can prove fatal, and once-in-a-decade hailstorms are nothing short of tragic.
The January 20 storm, which pummelled and pock-marked Canberra in a band which stretched from west to east, killed more than 600 flying-foxes from the Commonwealth Park colony, more than double the number first thought. Volunteers from ACT Wildlife cared for 60 injured bats until they were again strong enough for release.
That event has prompted an expanded extreme weather plan to make sure a quick response is always on hand in the event of more destructive weather.
The National Capital Authority, which is tasked with managing the bat colony, is also investigating a new misting sprinkler system to keep the flying-foxes cool on hot days.
The authority's manager of open space, Michelle Jeffrey, said she hoped to have the system installed by January, but this was a very optimistic goal.
"What we are looking at are misters that would normally be used in propagation houses. So it's delivering a very fine mist and they would only be activated on days possibly in excess of 35 degrees, 38 degrees or more, for very short periods of time," Mrs Jeffrey said.
"And that just may help reduce the effects of an extreme heat event, because the flying-foxes, they do suffer quite a lot from extreme heat but also the dry weather that we have here in Canberra."
Mrs Jeffrey said she was still getting engineers' advice on the project and works approval had not been finalised.
But ACT Wildlife volunteers are on standby for hot weather, and have access to a separate sprinkler system in case the hot weather becomes too much for the flying-foxes that come to Commonwealth Park each year.
Volunteer Denise Kay, who cares for flying-foxes at her home, said there was little that could be done to prevent the damage of a hail storm, but a team of about 30 volunteers would keep tabs on the colony this year through summer
Ms Kay said more than two days in a row of extreme heat were needed before the bats started to feel the effects.
"It might be a different year again this year because there's a lot of mothers and babies there and all of the bats we've had come into care at the moment have been mothers with babies. That's never happened before. Every year's different," she said.
Ms Kay said the main work of the volunteers was cutting bats out of fruit netting around Canberra at the start of each year. The peak period is when figs ripen in February and Ms Kay said gardeners in the ACT should use high-quality netting with small holes which bats don't get caught in.
She said the organisation was building a release aviary at the Jerrabomberra wetlands to better rehabilitate rescued flying-foxes locally. "Once they've recovered from netting injuries, they'll spend a couple of days there getting their flight up and ready, and then we'll just open the gates and let them out. That's the plan anyway," Ms Kay said.
The bats can carry Hendra virus and Australian bat lyssavirus, so members of the public who have not been vaccinated are urged to contact ACT Wildlife if they find a bat on the ground instead of attempting to help it.
To inform the draft flying-fox management plan, the authority monitored the flying-fox colony to gauge the bats' reactions to large Commonwealth Park events.
"Due to bushfire smoke and COVID-19, many planned monitoring events were cancelled as events and concerts were not able to proceed," the authority said in its annual report.
But Mrs Jeffrey stressed again there was no intention of moving the colony on because it was close to an ideal situation. "They're not above a park or a playground where children gather, they're not above a hospital or above people's cars. They're not above someone's residence, they're not disturbing a majority of people. They're in a location that we can manage and co-exist quite well," she said.
"And they seem to come back. They're coming back every year even though they know we have events in Commonwealth Park. There was concern that different events may disturb them, and yes there are events that will set them into the air, for example fireworks or flyovers by the low-flying aircraft, but they come back. They live with it."
