Of plagues and rodents: Australia’s war against mice

Evidence of bird deaths arising from the ingestion of poisoned bait has already been found in the central west of NSW. And that's in connection with the less toxic and commonly used zinc phosphide. Kelly Lacey, a volunteer for the NSW Wildlife Information, Rescue and Education Services (WIRES), found 100 dead galahs in a cemetery in Parkes at the end of last month. It was particularly galling for her, seeing as she had been involved in rehabilitating and releasing a good number of the birds around the area.

Bait poisonings of household pets and working animals have also been recorded. Peter Best, a veterinarian based in South Tamworth, estimated that one in 15 admissions to his practice had involved poisoned animals.

Such facts could only make another researcher at the CSIRO sigh. "If it's used properly," observed Steve Henry, "it should be a very, very low risk that a bird should find one of those grains of zinc phosphide and eat it." The bait was sound. The same could not be said for those using it. "Why birds start falling out of the sky is [that] people do inappropriate things." Such people used the bait in ways "not described on the label, or people make up their own baits."

When asked about her attitude to the problem, Healthy Rivers Dubbo convenor Melissa Gray suggested, with no detectable irony, that everybody wanted "the mouse plague gone, but there's no silver bullet." No silver bullets, maybe, but virtually everything else in the armoury of extermination. For the president of the NSW Farmers Association, the mayhem caused by such a poison as bromadiolone was worth the effort. Showing the somewhat patchy wisdom of his forebears, he accepted the lethal calculus. "It will cause poisoning in animals that eat the dead mice". That, however, "was the lesser of two evils".