Hoytwon,
The starling trap is a simple envelope trap that is used around the world to trap specific species of birds depending on the opening size of the slot. We made an earlier version that was permanent and worked fantastic. But we have multiple locations around us that are loaded with starlings so we made a smaller version of the first trap and anchored it to a trailer so that we could move it from place to place. Google envelope trap and it will give you a good idea how it works and show you how to build your very own trap (I highly recommend that you make it mobile that way it is more versatile).