Foreigners not welcome

Sydney scientists have teamed up with the native bush rat to evict the foreign black rat from areas of bush around the city.

New research from the University of New South Wales suggests black rats have held a mortgage on Sydney since 1900, when concern over the plague led to a bounty of 6 pence for every rat killed. Native bush rats, which look similar to the black rats, got caught up in the genocide and have never recovered, allowing black rats to take over bush areas.

A project led by UNSW will reduce the number of black rats in a study area around Taronga Zoo by 70 per cent, before re-introducing native bush rats in 2011.

Dr Peter Banks, a biologist at UNSW, said experiments have shown that once established, the bush rats will hold their own. “Putting two animals together into an arena…whoever was the resident won the fight,” he said.

Because bush rats do not climb trees, they do not pose as much danger to wildlife as black rats, who wreak havoc on birds’ nests and other wildlife. “We hope that by replacing black rats with bush rats, we’ll reduce that mass predation and maybe we’ll see some increases in bird life in these areas,” said Dr Banks.

But while native rats might reclaim the bush, Dr Banks said black rats are likely to remain unchallenged around urban areas. Peter Lamond, Senior Field Biologist for Rentokil, an extermination company supporting the study, said poor sanitation, apathy by shopkeepers and an unwillingness to invest in rat control measures would ensure black rats continued to thrive in the CBD. “Chinatown, The Rocks and Kings Cross would be…the places you would go first if you wanted to see a rat in its natural environment,” he said.

City of Sydney Council failed to respond to requests for information on rat control measures.

The Australian Research Council has awarded funding of $365,000 over three years to support the re-introduction of common native species as a block to reinvasion following pest control.

by Aaron Cook