I was watching a David Attenborough programme recently and it showed an Australian marsupial carnivore called a quoll, which is being wiped out because it's poisoned by cane toads (an introduction to control insect pests in crops - they never learn, eh). Bear with me on this one ..... They're now training the quolls not to eat the toads by capturing them, feeding them toad sausages laced with emetic then releasing them back into the wild. They're now seeing evidence the parents are teaching young quolls (quollettes?) not to eat toads. I was thinking of doing the same when the corvids have young in the nest next Spring - injecting a few sacrificial eggs with hot chilli paste and leaving them around the farmyard.