Why ground squirrels turn into ninjas over nothing

Whipping its tail may indicate a squirrel is ready for an attack. Video by Rulon Clark/YouTube

In a standoff with a rattlesnake, the California ground squirrel stares down its opponent. It might kick sand at the snake, whipping its fuzzy tail back and forth in a “come and get me” taunt. The snake lunges and the squirrel leaps into the air, twisting its furry body like a ninja. The squirrel successfully dodges the attack and warns fellow squirrels of the snake with its display.

But ground squirrels also sometimes flip out over harmless rocks, sticks and leaves. Why?

When facing a predator, these air gymnastics make sense, says researcher Rulon Clark at San Diego State University. Whipping its tail back and forth signals to the snake and other squirrels that the predator has been spotted, ruining the element of surprise for the snake, Clark says.

But Clark and his team believe that tail-whipping is not a taunt, but a sign of an alert squirrel — one that could flip out at the slightest surprise.

Clark’s team set up an experiment using a cork on a spring, the kind that normally launches fake snakes from cans in children’s toys. They set their squirrel-scaring device in areas where snakes had not been spotted and in places where snakes lived. Then they watched how squirrels reacted to their fake attack. The results of their study are published in the upcoming edition of the journal Behavioral Ecology.

In the areas where snakes hadn’t been seen, squirrels dined peacefully and barely flipped their tails. When the cork launched at them, they turned and scurried — no ninja moves.

But the squirrels eating where snakes had been spotted aggressively whipped their tails back and forth. And when the cork popped, more than half flipped into the air in a full ninja evasive maneuver.

“All four legs came off the ground and their tails were torquing around,” Clark says in an interview with Science News.

This tail-flipping could be a warning to predators that the squirrel is ready for an attack, and therefore not an easy target, Clark says.

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