Sounds like someone got tired of a flock of Grackles continually in their garden or something and put out some gopher bait (strychnine laced seed) for them.
A .177 pellet bounces off the damn things. And they drive away the purple martins that people put birdhouses out for.
It’s about this time of year they start migrating in large flocks, too. When they show up, it’s like a scene from “The Birds”, there are so many of them.