But Rodger is dealing with numbers as high as 1,000 kangaroos per square mile (400 per square kilometer), according to one survey done by the Commonwealth Scientific and Industrial Research Organization based in Canberra.
At such densities, kangaroos are frequently sighted in the city's bush parks, along roadsides, and in people's backyards.
So Rodger faces a major obstacle: He needs to find the best way of distributing his product to a large number of animals.
Ideally, Rodger says, he would like to put pills or pellets containing these contraceptive proteins in a feeder and allow the animals to come and get them.
"[But] animals are generally frightened of new things, and we assume they like one thing rather than another," he said. "Would they like a pellet that's sweeter to make it more attractive? Then there are demography issues, like which kangaroos would be attracted to a feeder."
The pellets also need to contain a protective packaging to prevent stomach acids from destroying the active ingredients.
The next three years of research, Rodgers says, will determine whether what sounds like a good idea can actually be an effective control method.
In the meantime, animal welfare groups are watching the project closelyeven though many are supportive of its aim.
"It is positive that the ACT government is investing effort in researching nonlethal kangaroo control methods," said Simone Gray, a spokesperson for ACT's Animal Liberation organization.
"Oral delivery seems to be a practical way to treat large numbers at once."
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