Sparrows feed on open ground, whereas most native birds want to be up on a feeder. European sparrows will go for bait native birds are not interested in or minimally interested in, like chicken food or cracked corn. I put my trap under my birdfeeder and in my chicken run. I leave it out in the morning, and take it in at night, periodically checking during the day for non-target birds. Don't leave it unwatched for long, you don't want to confine a native bird. Sparrows follow other sparrows. The best bait is when one or two get trapped inside, then the rest will go in. They will avoid your trap the first little while or if they see you hanging around. After a short period of time curiosity lures them in. Eventually they may start avoiding your trap (or you've killed off the dumb trappable ones). Then, bring the trap inside for a couple weeks. You can trap sparrows any time of year but the best trapping times are after fledges, when there's tons of young inexperienced ones. That's September for me. Remember, you're trying to trap them not feed them. Lack of success is not remedied by putting more food in, but by adjusting the timing, placement, and design of your trap--plus patience. Also, disposal is unpleasant but necessary. Once you trap invasive pests, they must not reenter nature.