for National Geographic News
Australians often laugh at some people's notion that kangaroos hop down the streets of the country's major cities. But in Canberra, the capital, that's no joke.
Large numbers of the animals roam throughout the city, which was designed to be a series of satellite neighborhoods linked through pockets of bush by arterial roads.
Now the kangaroosmainly the common eastern grey varietyhave become a huge public safety issue, often getting hit by cars. (Related: "Kangaroo Attacks in Australia Spotlight Growing Turf War" [May 2005].)
Concern is so high that the government of the Australian Capital Territory (ACT), which includes Canberra, has called in marsupial reproductive experts to try and find a humane method of controlling the animals' numbers (map of Australia).
The researchers' proposal: kangaroo contraceptives.
The Animal Pill
John Rodger, a professor at the University of Newcastle's Tom Farrell Institute for the Environment in Callaghan, is heading the three-year program. He says the effort is inspired by humans' ability to control their own fertility.
"We have demonstrated that it's possible to have a fertility-control vaccine just as you or I have been vaccinated against polio or other diseases," Rodger says.
"So rather than poisoning or trapping or shooting [kangaroos], couldn't we do what we have done to ourselves? And can we apply the appropriate technology to achieve that?"
Scientists have already developed working contraceptives for kangaroos. Similar to some human treatments, these fertility-control methods include hormones that can be injected or placed under the skin.
"We have used molecular biology to make a protein coat around the shell of the egg," Rodger explained. "The protein is the layer the sperm must interact with, so if it is in an inappropriate state then the egg can't be fertilized."
Such injections can be given safely and efficiently to small numbers of animals in confined spaces, such as zoos.
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