Monday marked the first attempt to displace the 5000 strong grey-headed flying fox colony with computerised recordings of loud industrial noise and banging sounds.
But at first light on Tuesday they were back in the trees.
'We've definitely seen the flying foxes respond to the stimulus of the noise disturbance and from that perspective it can be considered a success,' wildlife officer John Martin told AAP.
'It's a gradual process.'
Wildlife officers have rigged golf buggies with stereos to blast the flying foxes with industrial noise and distress calls for 45 minutes before dawn and 30 minutes at sunset.
Mr Martin said it would take anywhere from a couple of days to a few weeks for the flying foxes - they destroy the heritage landscape - to take the hint and relocate.
'I'd be looking more at somewhere between one to two weeks it'd be likely that the population should be noticeable smaller,' he said.
'But in saying that it could be slightly longer.'
Mr Martin said there are more than 200 colonies across the Sydney region, but some might seek out a life in the country and join rural colonies in NSW and Queensland.
There are permanent colonies at Parramatta, Centennial Park, Gordon, Wolli Creek, Clyde, Cabramatta, Avalon, Macquarie Fields and Kareela Park and it is hoped the flying foxes will leave the gardens to join one of these.
Flying foxes, unlike bats, forage using sight and scent and have hearing slightly better than humans, which makes using disturbing and annoying sounds an effective way to get rid of them, Mr Martin said
Source: Bigpond news