"I know I still get nervous when I notice groups of birds gathering. "
Hahaha, yes! For me it is really squirrels, they are creepy little things with their darting and unpredictability.

We have a hawk that visits our backyard looking for tasty morsels like my poor mourning doves from time to time. They're plump and slow moving so easy lunch for him. I've asked him very nicely several times to leave the poor things alone and opt for, oh say, squirrel tartar. But no go. What does it say that even a hawk doesn't care for the little tree rats! :-)