THE community is invited to share a "David Attenborough moment" at the March 6 social bat watch.
Wolli Creek Preservation Society spokeswoman Deb Little said the majestic sight of thousands of flying foxes taking off across the dusk sky was something not to be missed.
Ms Little said 13,000 flying foxes had created a camp between the creek and railway tracks and the site was growing each year.
"It was a seasonal camp for several years and they flew north for winter," she said.
"Now it has become a permanent camp that happened around the time that the Royal Botanic Gardens in Sydney removed its bats.
"They have to go somewhere."
Flying foxes received bad press but they played an essential ecological role of distributing seeds and pollen, she said. "The forests would be in trouble without them."
Ms Little said the flight was part of a "mass movement of animals that happen[s] every evening" across Sydney.
"It is an amazing sight to see and it is all within 20-30 minutes."
BYO blanket, chair and picnic to Turrella Reserve beside Wolli Creek (enter via Henderson Street, Turrella) from 6.30pm.
Wolli Creek Preservation Society, Rockdale and Canterbury councils, National Parks and Wildlife Service and Sydney Trains are supporting the event.
Details: bats@wollicreek.org.au