This maybe sound daft but i was speaking to a neighbour at my new address who has pakistani tumblers and fantails he said he has a lot of trouble with bop but what he has done has attatched little bells to the pakistani tumblers legs and since this he hasnt lost any tumblers only fantails he said the bop cant stand the wee bells anyone else heard of this! if it works maybe an idea for to put on a couple of your doos when out at the loft might just work