To make the trigger better use a piece of wood the same width as it is from the door pushed in to the middle of ur cage, cut this piece of wood in half then put in place,this under tension will hold the door open and can easily be triggered when the birds land on the pirch, crows can be crafty to catch, look around your land to see where the crows sit, i.e single trees around fields where they have good views around them. place the trap under neath these, bait this time of year would be carrion as the birds haven't started laying yet, it would be alot easier if you had a call bird but then ur