Years ago, back in the late 70's, my Dad used to belong to a dog club. I remember he had some type of permit from the state. Many nights we would stop at the local police station, show them the permit, let them know what bridges we were going to be at(usually back roads), and off we would go.

One guy would hold a flash light, and the other would use a net on a long pole to capture the pigeons from where they roosted under the bridges. My job was to remove them from the net and put them in the crate. When we brought them home, we had a pigeon pen at the farm. Nothing more than a caged area about 20 x 20 with a wire top and a small coop. When we needed them for training, we would go in at night and pick as many as we needed off the roost, and put them in a crate for the next morning. When supplies ran low, we would make plans for another night out scooping them up.

Bear in mind this was years ago. There was almost no traffic out after midnight. I'm not so sure the local police would think it was a great idea now a day, even if it were still legal to do it.