Authorities on the island say the animals eat opium poppies, get high and then hop around in circles. Attorney general Lara Giddings told a budget hearing: "The one interesting bit that I found recently in one of my briefs on the poppy industry was that we have a problem with wallabies entering poppy fields, getting as high as a kite and going around in circles. Then they crash. We see crop circles in the poppy industry from wallabies that are high."

Tasmanian Alkaloids field operations manager Rick Rockliff confirmed that wildlife and livestock which ate the poppies were known to "act weird". "There have been many stories about sheep that have eaten some of the poppies after harvesting and they all walk around in circles," Mr Rockliff said.

"But as growers we try our best to try and stop this sort of consumption, particularly by livestock, due to concerns about the contamination of the meat. There is also the risk to our poppy stocks, so growers take this very seriously but there has been a steady increase in the number of wild animals and that is where we are having difficulty keeping them off our land."

Tasmania is the world's largest producer of legally grown opium for the pharmaceutical market.

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