This is the trap most professionals use. It is effective and it folds into a flat-pack for easy transport and storage.
One way entry door, one either side, carry handle and top hatch to remove trapped birds
For effective trapping conditions, pre-bait the area where feral pigeon trap is to be placed for several days before the trap is sited. Corn or dried bread should be used for bait. After the pigeons become familiar with the feeding spot, place the pigeon trap over the feed. Bait the pigeon trap with a trail of grain on the outside of the trap and leading into the entrance door. Make sure you bait the inside the perimeter of the pigeon trap so the pigeons can find it. Leave the trap unset for several days so the birds become accustomed to it.You are legally obliged to check your trap daily. Food,water and shelter from weather conditions should also be supplied for all trapped birds. Any trapped pigeons should be humanely dispatched. Freeing the birds in an alternative spot is not effective. Pigeons have a very strong homing instinct and they will return to their roosting site even from hundreds of miles.
You can only expect to effectively trap birds for a limited time. Pigeons are very intelligent and will soon recognise that the cage is a trap.