You are not picking fight by letting them know they are poisoning your kittens. Firstly, they are littering on your property. Secondly, it is affecting your pets health- surely you are not on the wrong. They would have never taken you seriously if you had not said something to them.
File a report if it occurs again.
You've done just the right thing. They do it once again, call the police.
That's gross,what's wrong with those people.
Why can't you call the police, or the SPCA?
Lol. The idea of poisoned kittens eating bags of meat was funny. But seriously, that's kinda stupid, they ought to throw their trash in their own trash cans or something, not on your roof.