I have a number of serious concerns about the plan to use recordings of industrial noise to relocate the colony of the vulnerable Grey Headed Flying Foxes from the Royal Botanic Gardens (RBG) as reported recently by the Sydney Morning Herald, Central and Crikey. The bats are an important pollinator and seed disperser of a wide range of native trees, including many commercially important species. I feel there are serious doubts about what impacts the plan will have on the species and whether or not it will be effective.
The RBG wants to relocate the bats because they have killed or damaged a number of trees in the gardens. Those are reasonable motives but around 22 000 bats roost in the gardens – around 5% of the total world population – and they all have to go somewhere. It’s uncertain where exactly the bats will move to – while the relocation plan has identified a number of other potential roost sites around Sydney there is no guarantee these sites will be able to support this many individuals. They may be forced to take fruit crops from farms to survive (which will result in farmers once again crying out to be allowed to shoot them), if an urbanised population like this one can survive at all.
While the relocation program is timed so as to minimise disturbance to breeding it is impossible to entirely avoid causing problems. Even though most matings occur in April Grey Headed Flying foxes have a 6 month gestation period and young are suckled for another 6 months, meaning that there’s no time of year where you can do this kind of thing without disturbing pregnant females or dependent babies.
To make matters worse the RBG have a mobile sound system that will be used to drive the flying foxes away if they try to settle in Centennial Park or any other sites that they deem inappropriate. This means that even if the initial relocation avoids the times when unborn or fledgling young are most vulnerable there is no guarantee that follow up relocations will be able to be as sensitively timed unless the RBG is prepared to wait a year to carry out such relocations – which they aren’t.
While balancing the protection of the iconic RBG with the needs of the flying foxes is not easy this seems like a particularly poor solution. The Gardens management just don’t care what happens to the flying foxes once they leave as long as they don’t come back to roost and no one is complaining too loudly. When you add this to the Garden’s program of possum culling it makes me wonder what sort of management is in control of this public space which is home to so much of our urban wildlife.
Image by Justin Welbergen, use authorised under creative commons.