Watch out for the squirrel police. They ride around in tandem with the mattress police(who are looking for missing mattress tags). The squirrel police stake out squirrel nests for weeks on end and as soon as they see an illegal trapping, the squirrel SWAT team shows up to put the offender in the slammer for life. The only other alternative for them would be to go out and fight crime but they have their own priorities.
Contact your city/county/humane society/park dept/etc. and they may have traps that they will loan out.