The primary message a squirrel sends with its wagging tail is a warning. If they see something dangerous or suspicious, they wag their tails to alert other squirrels. They also use it to let predators know they've seen the danger, taking away the element of surprise.

Why are squirrels so twitchy?

Squirrels are so twitchy because they are prey for almost any animal out there, giving them a heightened keenness of their surroundings. ... When it's scared and detects any danger around it whatsoever, a squirrel's first reaction is to go into 'freeze' mode. If it's near trees, it will quickly climb up to safety.

What does it mean when a squirrel has its tail on its back?

The general gist is: "Stay away!" When upset or wary of predators, the tail works to warn others in the area of danger. It's also used as a territorial warning to keep other squirrels away from their precious acorn supply.