Wildlife experts are raising the alarm after months of concerning weather patterns sparked a “mass starvation event” for one of Australia’s native animals.

The Hills Wildlife Sanctuary in Sydney is seeing an unprecedented number of dead or dying flying foxes brought into care, with fears the cause of the tragedy is far from over.

“Over three to four weeks, we’ve started to see really large numbers of flying foxes coming into care,” Sanctuary director and CEO Ben Dessen said.

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“They’re all coming in emaciated, really, really thin and starving. It’s something that we really haven’t seen before, especially at this scale. There’s literally thousands of them coming in.”

Witnesses have also reported seeing flying foxes out during the day, including coming down low in trees and landing in people’s backyards — all uncommon and concerning in the mammals.

Wildlife sanctuaries throughout NSW have reported similar events, all pointing to one major issue affecting the native bats.

Many flying fox species, such as the grey headed flying fox, are listed as a threatened species. Credit: Supplied

“And right now is a really important time for flying foxes to feed. We’re in the middle of spring. A lot of our native gum trees and eucalyptus should be flowering at this time,” he said.

“All of our bottle brushes and paper barks, all of our native trees generally blossom at this time, which corresponds to the breeding season of the flying fox.

“Right now all the mums have pups, they have their little babies, they’re giving birth, they’re feeding milk, and they should be getting lots and lots of fresh nectar and food to feed their babies. Instead there’s basically a mass starvation event.”

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Flying foxes are vegetarian and live off a diet of nectar, pollen, blossoms and fruit and need to consume about 500g a night to stay healthy.

However, a delayed onset of native plants flowering this spring has caused flying bat population to be pushed to their limits.

“Some of these trees are blossoming and flowering later than they normally would, but the ones that are flowering have really poor nectar yields. There’s just not enough of it,” Dessen said.

Flying foxes are a keystone species and are essential for the pollination of Australia’s native gum forests, with numbers on the decline due to habitat loss.

“Our gum forests would ultimately collapse (without flying foxes) because they pollinate the trees and help them to survive and for the forests to thrive,” Dessen said.

Sydney Botanic Gardens chief scientist Brett Summerell said the weather plays a key part in how native plants behave.

“The starvation event affecting flying foxes is likely linked to a broader shortage of flowering and fruiting plants across parts of eastern Australia,” Summerell said.

“Many native plant species rely on adequate winter and spring rainfall to support flowering, nectar production and fruit development.

“Following an unusually dry winter and spring in many regions, we are seeing reduced flowering and fruit availability in some landscapes.”

Areas along the NSW east coast, inclduing Sydney, received approximately 50mm to 100mm of rain during the three months of winter, according to the Bureau of Meteorology, roughly 100mm to 200mm below average.

In the first month of spring, some areas only saw 25mm to 50mm of rain.

“Native vegetation, including eucalypts, paperbarks, figs and other flowering and fruiting species, play a critical role in supporting flying fox populations,” Summerell said.

“These events highlight the close connection between climatic conditions, native plant health and the wildlife that depends on these ecosystems.”

Flying foxes are vegetarian and live off a diet of nectar, pollen, blossoms and fruit. Credit: Supplied

The starvation event was likely linked to a drier than usual winter. Credit: Supplied

Dessen said his wildlife sanctuary is assisting other centres that have also been inundated in the area, taking in more than 50 sick flying foxes this week alone.

“It is unprecedented. This is a national crisis for these keystone species,” he said.

“We hoped that the state and federal government would bring some support but that hasn’t come yet.

“At the moment, we’re all doing this as volunteers and small charities out of our own pockets. We really need the community to rally behind us so that we can continue doing this important work and help as many bats as we can.”

Residents have been warned not to touch or pick up sick or injured bats due to the small risk of contracting lyssavirus. Iinstead people are urged to contact their local rescue.

“If you do have bats in or around the yard coming down low, you could hang some fruit kebabs by stringing up some chunks of apple or get a watermelon and cut it into big wedges and hang them up in a tree, so the bats do have some fruit to eat while the flowers are not producing.”

Dessen said his team are currently going through more than 200kg of fruit every week to feed the flying foxes in their care, with donations welcome to assist in their ongoing efforts.

While the issue is far from over, Dessen said locals can look to the future to help provide more wild food for local flying fox populations.

“The more native trees that we can plant in our backyards and neighborhoods, the better, because they’re going to flower and provide food for not only bats, but lots of other important pollinators like birds and insects as well,” he said.