Why do hamsters (and possibly other rodents too) sometimes freeze, motionless, for seemingly no reason?


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.

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.

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.

Yeah, it’s a stress response. It’s often said that “fight or flight” should more accurately be called “fight, flight or 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!”

Fight or flight is often mentioned but there’s also another evolutionary trait seen in some animals which is freeze.

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.

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.

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.

The mammalian freeze response. You have it programmed into your brain too. It is actioned by neurons in the basolateral amygdala. It is hypothesized that it evolved to prevent predators nearby from hearing our movements until we can calculate how to escape them.

They’ve evolved the response of holding very still when startled, since that reduces the chance they’ll be seen by a predator.

That doesn’t mean they feel horrified or are even consciously aware of their survival strategy. It is all instinct.

Animals can and do learn from experience, but they don’t get a chance to learn what not to do because they’ve already been eaten at that point. So this is an automatic response that has to emerge even when they are too young to understand it.

Incidentally humans can also freeze from fear but it takes a lot more fear to initiate this reaction because in humans it’s competing with a lot of other inputs and strategies. When it comes to prey animals, they do this constantly, dozens of times a day, without experiencing negative health effects that you’d expect if they were under extreme stress.

Even when rabbits are just playing with other rabbits they freeze up sometimes.

When I’m walking my dogs in the fields I often spot rabbits, but the dogs don’t notice them. Until the rabbits move, then they attract attention.

A lot of hunters are motion detectors.

So we’ve established they’re scared and likely would respond to any sudden movement but it also conserves energy. If they ran every time they got scared, they’d die of starvation (maybe not in captivity)

They have predators, and a lot of their predators have “hunter vision”.

We look at a room and see square things, round things, tall/short things, /red/blue/green things…

Hawks look at a meadow and see

gentlymovinggrass- **wigglewiggle**- gentlymovinggrass-

and their brains zoom RIGHT IN on that different spot because THAT’S LUNCH.

So I have found that hamsters will be still for a few reasons. If my hamster “meerkats” as in stands on her back legs and is still with her ears up, she is generally listening to figure out something, like where she is or what is around, or perhaps a noise she can hear. When my hamster “chameleons” as in takes careful back and forth steps, it means she is trying to sense and find out what is ahead of her by lettung her whiskers and nose try to sense something . When she “eggs” as in sits really still with ears up and on all fours, normally a sudden halt whilst going about regular activity, it means something has startled her and she is listening out and smelling for any clues as to what that is, trying to see if she is in danger. When she “sploots” as in is sat on her bum tilting to the side with her eyes closed, it means she is ready for bed. These are reasons that I have observed for my hamster being still.

u/printers_of_colors the real answer is that most predators have excellent vision but not always full colour so holding still makes it harder to see you especially if your colouring camoflages you against the background. A hamster or mouse will stop motionless instinctively because they think you won’t be able to see them.

I have pet Guinea pigs (not the same as hamsters but close enough). What I have found to help with the freezing and startled movement is just being around more often.

I place their cage in a frequently inhabited area like my bedroom or the living room so that they can see people often; therefore, becoming less afraid of our movements. I try to socialize them as much as I can with myself, my partner and yes, even my cat! So that they are less afraid and more trusting. When I enter the room, I bring them a small snack so that they begin to associate my entrance (a huge human) with something that is beneficial to them. I’ve raised my cat around them so that neither parties feel the need to run/attack. I also talk to them and pick them up as often as I can & give them lap time with a treat so again, my voice, hands, movement and body are now associated with something good for them rather than to be afraid of. I’m hoping that this helps. Main take away is try to socialize & desensitize your pet with your presence.