Why do hamsters (and possibly other rodents too) sometimes freeze, motionless, for seemingly no reason?
In: Biology
They have poor eyesight and saw something that startled them. Many predators use movement to track prey. Prey animals are just playing it safe.
Yeah, it’s a stress response. It’s often said that “fight or flight” should more accurately be called “fight, flight or freeze.”
The unofficial term for it is going “tharn.” Coined by Richard Adams in Watership Down. Don’t know what the scientific term is.
There’s reasons to believe that humans also exhibit a form of this, where under periods of immense stress a person just shuts down.
Like that scene from Jurassic Park with T-Rex. If you don’t move, he can’t see You. Hamster probably think of You as a T- Rex. 🦖
This is common behavior among prey animals in general, especially small ones. Many predators–ourselves included!–see movement more easily than anything else. This is especially true for predators with less color vision than we have. Prey animals have evolved to freeze when threatened so that predators overlook them.
The thing is, animals can’t always tell what is and isn’t a threat. And it’s all right to freeze when there’s actually no danger, but not great if you *don’t* freeze when there *is.* So rodents and other small mammals are constantly on alert, and anything that catches their attention as a potential threat is a reason to freeze momentarily while they check to see if it was actually something that might eat them.
It’s their response to being startled. In most creatures a startle or fear response will trigger one of three responses: Fight (they will fight), Flight (they will run away), or Freeze (they will freeze — totally motionless).
These are fundamental responses to fear which aid different species in survival — so it’s not really for no reason, it’s for survival.
Heard a good example of fight, flight, or freeze today, specifically on the “freeze”: If you’re birdwatching, and there’s a bird in a tree, you probably won’t spot it until it moves, even if it has brightly colored feathers. That’s why fear can make you freeze up and breathe more shallow, because movement is really noticeable to predators obviously, even very slight movements. So it’s kind of hiding.
To simplify, the responses to threats are *actually* “Fight, Flight, or Freeze”, and the newer understanding of that has massively changed our interpretations of intelligence among animals, which was previously based on the wildly-flawed “mirror test”… which plenty of *children* can’t even pass if they’re unfamiliar with the concept of reflections.
Fight or flight is often mentioned but there’s also another evolutionary trait seen in some animals which is freeze.
Same reason rabbits do, I’d think. “Oh shoot, there’s a human. He doesn’t see me. He doesn’t…. ooop…. he’s too close! RUN!”
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