Killing predatory pests like rats and possums with poisoned bait helps protect rare bird species. But if the birds eat the bait, they die too, says Agresearch of Hamilton, New Zealand. So the company has been experimenting with additives that deter many birds from eating poison (WO 2004/14).
A small dose of a chemical called pulegone makes the bait smell of mint and deters casual pecking. A little anthraquinone makes the bird feel ill after a small peck, and a bright blue dye helps the bird remember what makes it ill. After four days robins were pecking blue bait…
