To legally trap tree squirrels, the management company should have an animal removal permit issued by an IDNR district wildlife biologist or have hired a licensed nuisance wildlife control operator. It is highly unlikely that a squirrel is going to enter a trap that doesn't have any food in it. By law, traps must be checked at least once a day. And any animals that are caught should be removed as soon as possible (i.e. ideally as soon as they are caught, but no longer than 24 hours after they were captured). It is inhumane, and illegal, to leave an animal in a trap without food or water for more than 24 hours. If you find that animals are being left in traps longer than that, you should contact your local IDNR Conservation Police office. Contact information for those offices can be found on the Find a Professional Page of this website.