where i live, choppers train here every year. can easily see 8-10 choppers here flying for practice.. then they disperse leaving the 2-3 local ones to fly and do there thing. they start normally in about june. since theres so many gardens around here, they take pictures and pot where the gardens are at, and pick the biggest ones to start with and work there way down. they dont stop till october, even then ur not safe cuz they will come to ur house (backyard gardens), and take ur dry pot while ur trimming.
can u be a bit more specific about where you are talking about?