Flying fox rescuers in Sydney are experiencing "the worst season ever" as a record number of bats get caught and injured in nets used to protect backyard fruit trees.

The predominant species, the grey-headed flying fox, usually feed on eucalypt blossoms, but a poor bloom season across the city combined with high summer temperatures has drawn bats to suburban backyards.

"We're completely overloaded with bats coming in from netting," Sarah Curran, rescuer with the Sydney Wildlife Service, said.

"We're really struggling with numbers ... it's the worst netting season we've ever experienced."

Ms Curran said the most common rescue mission involved a bat caught in a large aperture net used to cover fruit trees.

Since January 1 animal service WIRES has rescued 1,076 flying foxes from backyards across New South Wales, the majority of the calls being netting incidents.

Tree netting guide Protect individual fruit using fruit protection bags

Protect individual fruit using fruit protection bags Use a densely woven net that doesn't need a frame

Use a densely woven net that doesn't need a frame White nets are best

White nets are best Use the finger test — choose netting you cannot poke your finger through

Use the finger test — choose netting you cannot poke your finger through Mesh size should be less than 5mm Source: wires.org.au

That has equated to about 20 rescues a day, compared to only a dozen per week in previous years, according to WIRES rescue office manager Kirstie Harris.

The comments come nearly a year after scientists told ABC Radio Sydney that the number of bat roosting sites were increasing as colonies moved into urban areas in search of food.

Last week thousands of bats died during a heatwave across the state.

'The bat ate the mangoes'

After noticing half-eaten mangoes left strewn across his backyard this week, Concord resident TK Hoh woke on Tuesday morning to find a flying fox caught in the net he used to cover his tree.

"I walked to my beloved mango tree and noticed a pile of leaves on the ground and when I looked up, lo and behold there was this creature staring at me," Mr Hoh said.

"It was all entangled in the net.

"This was the first time in five years since we've had this mango tree."

Volunteer WIRES rescuer Meg says she has been rescuing up to 20 flying foxes a day. ( Supplied: TK Hoh )

Mr Hoh called WIRES whose rescuer arrived within an hour to free the animal.

"The WIRES lady came straight to the back, cut the net and wrapped the bat up in a blanket," Mr Hoh said.

Don't attempt to free the bats

Stanmore resident Luciano Zappulla also had a bat caught in his net this week after it tried to eat from his fig tree.

"The poor thing, I tried to free him but it was going to bite me," he said.

"I don't know how it got inside there.

"Next time I'll put in a net with smaller holes."

Large holed nets used to cover fruit trees can easily trap wildlife searching for food. ( Supplied: Sarah Curran )

Ms Curran, who has recently also rescued snakes and birds caught in backyard tree nets, advised residents to use nets with a fine mesh that "you can't poke your finger through".

She also said to never approach a tangled bat to prevent further injury to the animal and to avoid getting bitten.

Under 1 per cent of flying foxes may carry Australian bat lyssavirus, a virus linked to rabies.

What happens to the bats

Ms Curran said all flying fox rescuers, of which there are just under 300 in the Sydney metropolitan area, have been vaccinated and trained to rescue the animals.

She said netted bats were usually distressed, suffering from heat stress and injured wings.

Sarah Curran with rescued bats that are recuperating at her home. ( Supplied: Sarah Curran )

After a rescue Ms Curran takes the animal to the vet to get them pain relief and fluids.

"I take them home and care for them for a couple of weeks and treat their wings with anti-inflammatories," she said.

"After that I take them to flight facilities at the Lane Cove National Park and they're released back into the wild."

Ms Curran said she was currently caring for about 30 bats at her home in Wahroonga.