I didn't read that study but I have a British Wildlfe book which talks of 'homing' behaviour of snails marked with tippex who came back from about a mile and a half away - perhaps it was referring to the same study. Recently R4 covered the same subject but i missed it darn it. I take mine to Dartmoor, about 5 miles away, but I wish there was an easier, snail friendly solution. Not keen on sacrificing them to the birds. If I were a snail, I would object. When their heads are out, they look almost sentient and intelligent. Not that that should make any difference really, if they are suffering they are suffering, high IQ or not. I would love to hear from someone who has an answer to this problem. They eat the best bits of my garden. Are there any plants that repel snails, or make them eat less?! Or sterilise them?