Environment Minister Simon Corbell announced a trial involving up to 200 kangaroos this week, to test whether the fertility control drug GonaCon can be delivered effectively via dart. Of the 200, about 150 would be vaccinated, some with darts and some by hand injecting, with others forming a control group, government senior ecologist Don Fletcher said.
The kangaroo fertility trial will include capturing kangaroos to check the extent of bruising and injury from being shot with a dart.
The darts were relatively heavy, not only carrying the drug but also a marker dye. They must be shot much slower than a bullet so they didn't damage the kangaroos but hit their target with the correct impact to deliver the vaccine. That meant the darts travelled in a curved, imprecise trajectory, making accuracy more difficult. Kangaroos were lightly built and there were a number of reports from interstate of them being injured by darting. The trial would test the distance at which the dart could be delivered accurately and humanely, he said.
The government doesn't want to name the 10 reserves, but Dr Fletcher said the populations were small, some of them contained, including golf courses and urban parks, allowing accurate assessment of whether a sufficiently high proportion of kangaroos could be rendered infertile to affect the population growth rate.
"The ideal test … would indeed be with multiple large populations, but you have to take the small steps before the big steps," he said.
Firearms tranquilliser expert Marcus Fillinger, a strong critic of the government's approach to kangaroo control, questioned whether the expertise existed in government to deliver the drug properly.
Commercial shooters aimed at the head or body of a kangaroo, whereas a dart must be delivered into the muscle mass - the large thigh muscle - where it could release slowly, he said. If it went anywhere else in the body, it risked injury to the kangaroos which had fragile chest cavities. It could puncture a lung, rupture a kidney, break ribs, or if went in the head, kill or blind an animal, he said. Too much velocity could cause impact damage.
Mr Fillinger said he fired 200 darts a day in target practice to maintain proficiency and has concerns about the experience of those involved in the trial.
"They're not tranquilliser firearms professionals, they're not marksmen. They're reading the back of the pack and away they go."
Mr Fillinger, who runs a wildlife rescue charity and recently announced his candidacy for the ACT election as an Independent, questioned the $500,000 cost of the kangaroo fertility trial, saying GonaCon cost $US5 a dose and the darts $US9 each.
The government should go to open tender, which would deliver a much reduced price, he said.
But Dr Fletcher rejected the criticism, saying one of the vets on the program had "darted thousands and thousands of animals around the world".
"There's very substantial experience in our group," he said.
Mr Corbell's spokesman said the budget included the cost of government and CSIRO staff, a wildlife veterinarian, permits for the use and import of GonaCon, darting equipment, a vehicle, veterinary supplies, and analysing blood samples.
Regional Friends of Wildlife Spokesperson Frankie Seymour said the organisation did not believe population control was necessary, however it would support fertility control if it ended the annual cull.
"Cull after cull, without any evidence either that the kangaroos are doing harm or that the culling is having any benefit, are simply not acceptable," she said, accusing the government of inconsistent methods of counting kangaroos and "arbitrary and incomprehensible" assumptions about kangaroo carrying capacity.
Dr Fletcher said it was wrong to assume that fertility control could replace culling. Culling was necessary to get the population right before fertility control began, he said.
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