Rare bats to live inside Sydney artwork

Australia's most expensive sculpture will be a haven for native species.

IT'S CERTAINLY AN extravagant upgrade from the branches and dead trees they normally call home. Several threatened species of bats may soon take up permanent residency in the walls of one of Australia's most expensive sculptures.

It's hoped the new $4.5-million work in the Royal Botanic Gardens will welcome a number of threatened species into its fold while charming human visitors with its artistic beauty. The massive work, believed to be the most expensive ever commissioned in Australia, will use 200 tonnes of sandstone to create a flowing wave form sculpture overlooking the harbour.

One threatened micro-bat, which eats up to one thousand mosquitoes per hour, will live within a hollow structure woven from 22,000 quartz stones inside the sculpture walls, says Dr Tim Entwisle, executive director of the Botanic Gardens Trust. Aside from the useful bat, it's expected rare fauna will grow among the moist sandstone while bees will occupy wooden blocks placed within the structure. Gaps deliberately left in the sandstone waves will allow other struggling city species to find a quiet new home.

A naturalist from the Australian Museum who assisted with the sculpture, Martyn Robinson, says while most public spaces eventually became habitats for plants and animals, the encroaching species are generally viewed as a nuisance.  "This sculpture is the reverse. It's been specifically designed to be colonised and as time goes on it will become more than it was, will change in appearance and increase and fluctuate in diversity," he says.

Biodiverse beauty

"The structure will be available to any species of insectivorous bat which needs it and it is not unusual for several species to share a roost," Martyn told Australian Geographic. "Though only some species of insectivorous bats are listed as endangered, all species seem to be in decline primarily due to lack of suitable daytime roosting site. Dead trees and hollow branches are sought out and removed by firewood collectors and councils worried about falling timber and threats of legal action. Without these the bats have fewer places to live and hide by daytime."

He says that likely tenants could include the large-footed myotis bat (Myotis adversus), the large-eared pied bat (Chalinolobus dwyeri), the golden-tipped bat (Kerivoula papuensis) and a range of other species.

The sculpture also recognises the indigenous Gadigal people, with the artist weaving the outline of a traditional Aboriginal shield into the quartz stones. The unique structure was funded by the late Sydney finance executive and keen art lover Ronald Johnson, who stipulated that the bulk of his estate be used for a large artwork overlooking Sydney Harbour. Ronald, who donated substantial sums of money to other causes in his lifetime, died in 2003 at 80 years of age.

The Royal Botanic Gardens announced on Tuesday that the sculpture will be open for public viewing during its construction.