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The way rodents move across gaps

JonJon Lemming
edited January 2016 in Behaviour
I've always wondered about this. It's much more noticeable in rats, although mice and I suspect other rodents do it as well.

When a rat or mouse has to climb across from one surface to another and it involves stretching to bridge a gap, they have this really clever way of moving their body mass across. The overall appearance is that they "draw" their back legs behind them without having to hop, without overbalancing and without any signs of them holding on like grim death with their front paws.

I've watched it countless times but never filmed it in slow motion to see. Do they suck all their guts forwards or something?

Anyone else wondered about this?
Ask not what your rodent can do for you...


  • zany_toonzany_toon Mouse
    Posts: 631
    You aren't the only one who has wondered this Jon!! I always thought before seeing them that they would pull themselves across gaps much in the way a cat would, with a graceful hop. But they make it seem as if it has far less effort. If you ever manage to film it in slow motion I'd love to see it :)
  • AnnBAnnB Mouse
    Posts: 1,053

    I think you must both have more acrobatic mice than mine then! My lot are really clumsy and I have to make sure there aren't any large gaps between their hammocks etc.

    I'd love to see some footage in slow motion too. I don't have any good action shots of the mice but I do have a funny pic of my old cat in the middle of a hop from one piece of furniture to another.

    2.05 Doodle 032.jpg
    2288 x 1712 - 790K
  • JonJon Lemming
    edited January 2016 Posts: 147
    Well that's the funny thing; it's much more noticeable in rats than mice so it might be hard to capture at the moment because I only have mice.

    With rats, they "suck" themselves across gaps very obviously, but nimble they are not. It always makes me laugh how in Hollywood films, the evil rats always announce their presence by squeaking as they walk along and they are also incredibly deft at climbing.

    Oh sure, my Ex's rats could climb (the Christmas tree, her trousers, the chairs) but they were equally good at losing their balance and toppling over. One rat we had, in many ways The Definitive Rat of our family's experience, Loki, was terrified by heights and probably with good reason as all he seemed to do was fall off stuff.

    I recall one time he seemed to have vanished from his play area in the hall. He was fairly young and so, worried to death that he might have totally escaped, I climbed over the barricade and into the tiny hall. "Loki?" I called. There was a short pause and then I was answered by one tiny, plaintiff little "cheep!" Odd. Never heard that before, "Loki?" Again, "cheep!". Oh God, he's stranded himself again. It was coming from the coats above the ledge he liked to climb onto.

    Gingerly, I parted the middle two coats and there, staring at me with beady black eyes out on stalks, was poor, stranded Loki. The great waddling idiot had got himself up there and then couldn't fathom his way down again.

    Another time, I was sat minding my own business when I was aware of him out of the corner of my eye. I looked across at his two-level cage and saw Loki, hanging by both hands from a horizontal wooden ladder. Before I could leap off my chair and rescue him there was the by-now-familiar pause-plummet-crash! He was unhurt, but honestly!

    Loki was very, very smart. He even understood a number of English phrases. Or perhaps I should say he related certain given strings of vocal sounds to a certain action or consequence. He knew the following:

    Fish... and chips (you had to say it like that. Loki would get excited before we even went out to fetch them)
    Do you want your octopus? (one of those soft, dome-like things with four cloth tunnels leading into them)
    And of course his name.

    This was dear old Loki:


    Ask not what your rodent can do for you...
  • zany_toonzany_toon Mouse
    Posts: 631
    AnnB said:

    I think you must both have more acrobatic mice than mine then! My lot are really clumsy and I have to make sure there aren't any large gaps between their hammocks etc.

    I'd love to see some footage in slow motion too. I don't have any good action shots of the mice but I do have a funny pic of my old cat in the middle of a hop from one piece of furniture to another.

    I think it depends on the mice Ann :P I know Mercury couldn't do graceful even if if his life depended on it X( He ends up looking more like a mouse shaped version of the cartoon Flubber with a huge jelly belly X( Your cat looked far, far more graceful and acrobatic :)

    Your story about Loki really made me laugh, Jon :P He sounded like he was a troublesome rat who couldn't cope with the bother he got himself into :X
  • JonJon Lemming
    edited January 2016 Posts: 147
    I think this image may hold part of the answer to how rodents do this "gap trick": It's a picture (from a few years back) of a little doe I had from a local pet shop. Her name was Pointer, for the very reason that she liked to anticipate getting somewhere by stretching forward as we arrived. This is one of a series of stills I got of her "pointing":


    If you look at the positioning of her hind legs and the centre of mass, it would seem logical to suppose that in the next half second or so, she would push against my finger with her back feet and then reach out to grasp the toy with her front paws. I guess she'd then follow this by keeping her body rigid and drawing her back legs over straight afterwards.

    For mice, because they are faster in some ways than rats, it might look like a form of hop, but I think in actual fact it must be an ability that rats and mice have to keep themselves rigid, combined with a shifting of mass inside their bodies.

    What do you reckon? I guess we will only know for sure when I can get it on slow-motion film.
    Ask not what your rodent can do for you...
  • zany_toonzany_toon Mouse
    Posts: 631
    That's a fab photo Jon :) And yes, I do think what you've described makes sense in terms of how they might be moving :)
  • yoonicornyoonicorn Lemming
    Posts: 24
    This probably isn't particularly helpful, but there's a video here which shows a multi jumping/walking to someone's hand:

    You can slow the video down to 1/4 speed, although it's not very good quality. I still can't figure out how they do it, especially considering how stubby he looks!
  • zany_toonzany_toon Mouse
    Posts: 631
    That was a good find Yoonicorn :D And it looks like Jon's hypothesis was right about them stretching over after balancing themselves then pushing off with their hind legs :)
  • JonJon Lemming
    Posts: 147
    Very interesting video, thank you for posting it yoonicorn.

    Having downloaded it and dumped it into a video editing program I think I've worked out what Puck (isn't he lovely!) is doing. Most of the crossings he makes are straight hops, but the second one he does gives it away nicely. Even at single-frame level though it was hard to work out but I finally figured it after several viewings. It's so quick that this was the only way to see it even remotely much less clearly.

    Yhis is what I think happens and it's a clever little rodenty illusion:

    At around 1'18", he's stretching as far across as he can. Both sets of feet are still planted on the right-hand side; the side where Puck is sitting to begin with.

     1. He stretches forward just a little further and reaches his front paws out to make contact with his owner's hand.

    2. Once he's grasped the other side with his front paws, he rolls forward slightly on them to move his body forwards. A bit like a sausage on a conveyor belt.

    3. Once his shoulders are over his front paws, he pushes up very slightly on them to take the weight.

    4. Whilst he is doing stage 3, he is still rolling his body weight forwards and also preparing a final push with his hind legs. This really is the point of no return.

    5. With a deft and lightning-fast little shove from his hind legs, he propels his rear end across the gap.

    6. His  hind legs land right between his front paws, with his bottom sticking out over the gap and his tail out rigid to help him balance. It's here that he looks all bunched up and bulbous and this is the part that creates the illusion of "sucking" body mass  forwards.

    7. His front paws are then moved forwards and away from his hind legs, stretching his body out and making him look more like his normal shape.From this point on he can just walk away normally.

    Well I'm blowed!

    Ask not what your rodent can do for you...
  • KawaiiKawaii Lemming
    Posts: 257
    Thank you Jon haha, that's a lot of work you put in to answering this!

    Is this only relevant for all the mouselike/ratlike rodents?

    .....Hmm. I wonder if the chins "hop" in the same way? (Obviously they jump like a hare, but for going down levels? I wonder.)

    Proud owner of 2 chinchillas and a dwarf hamster

    (chins for the win!)

     If I'm not active I have probably forgotten my password (again)....

  • zany_toonzany_toon Mouse
    Posts: 631
    That's fab work Jon :D Thank you for doing that, it must have taken you a while :) It sounds like mice put a lot of work into something that they make look very simple :)
  • JonJon Lemming
    edited February 2016 Posts: 147
    It really wasn't that hard to be honest. Just a case of copying the video with a sufficiently high frame rate. Even at something crazy like 60 frames a second, the crucial bit where the rodent actually moves the bulk of its weight across the gap was almost a blur. I felt there was something that the eye could recognise at normal speed but which was impossible to verbalise without footage to slow down. That's why I got interested in this in the first place.

    I've only ever seen rats and mice do it. I don't know how chinchillas move because I've never really observed one at close quarters other than in a pet shop. With other rodents like degus, the chances are it could be a completely different set of muscles that they use.

    Given that a lot of rodents can be depicted (certainly as they get into middle age) to a circle with a triangle sticking out of it, a big round backside and a pointy nose)  it  probably makes the most sense for them to transfer their weight in this fashion.

     Whatever it is, it has to be instinctive rather than planned.
    Ask not what your rodent can do for you...
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