Sydney's bats not easily scared off
Author: Pauline Askin
Sydney's Royal Botanic Gardens has tried all of the above in a fruitless effort to disperse a colony of some 5,000 grey-headed flying fox bats which have made the inner city gardens their home after fleeing developments up and down the coast.
The problem is that the species is the world's largest flying bat, weighing four kilograms (nine pounds) and with a one metre (three feet) wing span. By sheer weight of numbers as they hang upside down, they are damaging the garden's 180-year-old trees.
"They're doing a fair bit of damage because of the concentration in that area," Patrick Houlcroft, the garden's environmental coordinator, told Reuters television.
"We're hoping via different means if we can try to spread them more evenly across the site," Houlcroft said.
After early failures of python excrement and chilli paste, gardens staff are now hoping they can scare the bats off using a sound system. Each morning from just before dawn, speakers broadcast sharp and abrasive noises for about two hours.
"The sound is set at high volume with a mixture of shrieks and bangs - an assortment of long settling noises we hope will deter them from a few particular trees," Houlcroft said.
"They are very stubborn creatures."
The urbanisation of coastal land north and south of Sydney has destroyed the flying fox bat's traditional habitat, forcing them to migrate to Australia's most populated city to seek refuge in the botanic gardens.
Australia's National Parks and Wildlife Services has classified the flying fox bats as "vulnerable", making them a protected species and in turn making the garden's efforts even harder.
Houlcroft said the bats were not a menace, contrary to what some office workers may think as they watch thousands fly across the harbour each night hunting for food.
Each evening they take off and forage in a 12 to 25 mile radius before returning in the early morning.
"We are mindful of the fact that in general across Australia their numbers have crashed," said Houlcroft.
"So whilst people complain about the enormous number in Sydney, it's part of a bigger picture of overclearing and species being forced into these safe havens basically."