I love this video of Piggy responding to an alarm call.
I know that particular call well. It's sounded around here when a hawk is in the area, or when Riley the Cat walks around. Riley the Cat drives the squirrels crazy, although he doesn't appear to be the least bit interested in them (although he's very interested in the dogs).
I do question the idea of upsetting the squirrels. I've seen squirrels that became so rattled that they couldn't stop squawking and shaking long after the threat had disappeared. I recall one who kept eating nuts (to calm down) and kept on squawking between chewing. It was like trying to cure the hiccups! Apparently once they get started it can be very hard to stop.
But that wasn't the case with Piggy, who was able to handle the alarm without panicking and remained watchful throughout. I think Piggy has the makings of an alpha squirrel. You know, one of the squirrels that stays behind to challenge the invader after the other squirrels scurry.
I'm fascinated by the human-to-squirrel interaction that went on here. Our friend has the squirrel sound down pat and did an amazing (and amusing) job of communicating vocally with Piggy!