they aint wood pigeons are they?? i suspect they are ferals?? its easy to trap them if you have the time to make a trap an bait it, the bigger the trap the better, i cleared a farm not so long ago, i built a cage or small aviary as such, i made it so it could jsut bolt together an be built an dismantled in minutes, at the bottom i put some bob wires an fed the trap, try an stay out of sight itll fetch them in easier, i killed over 200 pigeons in a space of a week