Bat out of hell: noise to send flying foxes fleeing

BATS will be blasted from Sydney's botanical gardens with "industrial noise", widening the debate over whether they should be shooed away.

FLYING foxes will be blasted out of Sydney's botanical gardens with "industrial noise", widening the debate over whether the creatures should be shooed away from people and horses vulnerable to the Hendra virus.

Queensland's chief vet, Rick Symons, yesterday questioned whether scattering colonies could backfire by making the fruit bats more infectious.

Those roosting in the lower section of Sydney's Royal Botanic Gardens - in a colony 5000-strong but capable of expanding to 22,000 during summer - will be moved on next May under permits issued by NSW and federal authorities.

Motorised buggies are being kitted out to harass the creatures with "industrial noise" in 10-minute bursts. These will alternate between pre-dawn, as the bats settle in to nest, and pre-sunset, putting them to flight early to forage for food.

Royal Botanic Gardens wildlife officer John Martin said similar programs had worked in Melbourne and Adelaide. The idea was to disrupt the bats with sounds of "banging and clanging", he said.

The noise level would be 80 decibels at 10m, which was less than the 110 decibels a chainsaw would make at the same distance.

The issue of dealing with bats has been given added needle by the unprecedented number of Hendra outbreaks in Queensland and northern NSW since last month, and confirmation this week that a dog had for the first time been infected in the field.

Flying foxes can infect horses and, through them, people with the potentially lethal virus. Four of the seven people known to have contracted it died.

Queensland Liberal National Party leader and former Brisbane lord mayor Campbell Newman wants to disperse troublesome bat colonies with smoke bombs and helicopters, and has even suggested cutting down trees in which the creatures roost.

But Dr Symons said research had suggested that environmental stress, such as food shortages, made the bats more infectious and dispersing them could compound this.

He had advised the government and opposition LNP against moving colonies, partly because "you don't know where the bats might go".

"We have not done definitive research on whether dispersal itself would cause the virus to spread," Dr Symons told ABC radio yesterday.

"We do know in mammals stress increases the risk from viruses and the risk of increased virus (in bats).

"There's a possibility in dispersing them it will cause stress and increase virus load."

Premier Anna Bligh seized on Dr Symons's remarks to argue that Mr Newman's plan would worsen the Hendra problem.