Out here, the ravens are our neighborhood watch. They have certain blocks that they patrol, always one spotter (from a tree or building), and one on the wing or walking about.

Ravens are about the size as a 4 year old human. They love McDonald's french fries, alas: they will sort through the refuse bins, and aren't too careful about putting the trash back.

I often wonder about encouraging them to pick up litter and recycling. I am sure they could handle the job. There's at least one instance documented of getting corvids to pick up trash...