This is a great idea. I wonder if it would also be able to read those tags that are implanted into some pets such as the "homeagain" tags (maybe they aren't RFID or don't have enough range?) If so, it would work great for tagged pets without a collar. Also, since many pets bear such tags, a log could be kept of attempted accesses.

The aftermath of such a parade (these days) is quite interesting. The Fire Department hoses down the streets, turning the blowing paper into a slush. Then with brooms the Sanitation Department moulds the slush into piles and picks it up.