Sloth defecation is for mating

A while back I put up a post and a video showing the bizarre behavior of sloths when they have to defecate: once a week they make the long, slow climb down to the base of their tree, dump their load, and then retrace their steps up. I suggested four hypotheses for this behavior, and decided that the most likely one was to identify their location to potential mates.  There were lots of comments, and most people disagreed with the “mating” idea because, after all, how would one sloth ever find another if they had to climb down a tree and sniff around other trees? It seemed inefficient.  Now, Becky Cliffe from the University of Manchester claims she has some support for the mating hypothesis (I am putting below a comment she just added to the earlier post):

I am doing the study and I can shed some light on this matter! To cut a long project short, I have been monitoring sloth behaviour, reproductive activity, thermoregulation and metabolic activity for the last 12 months and can tell you that the defecating at the base of the tree is almost certainly linked to finding a mate.

You won’t find any literature on this at the moment but I can tell you female sloths have a very regular 28 day reproductive cycle, during which, they are in heat for 10 days. During these 10 days,they actually let out regular high pitched screams that attract males from up to 700m away, and they descend to the same spot at the base of the same tree daily to go poo/pee (even if it is just the tiniest amount!)

It also takes them an average of 31 days for food to pass from ingestion to excretion … amazing! And yes, their body temperature CAN fluctuate up 8 degrees over the course of a day. And the respiratory rate can range between 6 breaths per min to 120 !

Oh and the stuff about them being half deaf and half blind… completely false and I have no idea who spouted that one originally!! Very interesting animals 🙂

Just to show this is legit, here’s a YouTube video of Becky with baby sloths:


  1. Dominic
    Posted June 24, 2011 at 12:33 pm | Permalink

    David Attenborough told the tale of a sloth supposedly being deaf in his radio series later a book, Life Stories. I have the CD but not with me so I cannot check exactly what he said. Oh – it is here –

    • Dominic
      Posted June 24, 2011 at 12:34 pm | Permalink

      Sorry Jerry – did not mean to embed that…

      • Dominic
        Posted June 24, 2011 at 12:47 pm | Permalink

        Anyway, well done Becky! Which species is she studying?

  2. entropy
    Posted June 24, 2011 at 12:36 pm | Permalink

    i want to marry her. 8)

    • Posted June 24, 2011 at 1:12 pm | Permalink

      In that case, you had better start climbing down your tree.

  3. Rod
    Posted June 24, 2011 at 12:53 pm | Permalink

    Leeds or Manchester?

  4. saintstephen
    Posted June 24, 2011 at 3:17 pm | Permalink

    Professor Coyne obviously loves the smell of his sloth dung hypothesis this morning…

    … because it smells like victory.

    (Okay, from sloths to Apocalypse Now is a bit of a stretch. Sorry.)

  5. madamX
    Posted June 24, 2011 at 5:11 pm | Permalink

    Doodoo love advertising? I like it!
    This doodoo was dumped for you by a young, two-toed, single female sloth. Enjoys eating leaves and sleeping in. Looking for a sexually able male with good olfaction and hearing that can climb this tree.

  6. Marella
    Posted June 24, 2011 at 6:03 pm | Permalink

    If the female screams so she can be found then I don’t understand why she needs poop at the bottom of her tree as well. And it offers no reason at all why the males poop at the bottom of their tree everyday. Sorry, this doesn’t hold water.

    • Posted June 24, 2011 at 6:41 pm | Permalink

      I’d suppose to tell them which tree to climb when they a tracking the sound. It would suck if he chose one two trees over.

    • Becky Cliffe
      Posted June 25, 2011 at 12:21 pm | Permalink

      Well it seems to be that both males and females have a habit of pooping only at the base of certain favourite trees – communal spots. So when the male makes his weekly trip down to the ‘toilet’, it takes him more often than not to the exact same spot where any local females have been. And the in heat females are expending SO much valuable energy (considering they have so little) and putting themselves at huge risks by coming down daily, this must surely be to maximize the chances of a male catching her scent.

      I must add, the study is only looking at the 3-fingered sloth. I don’t know if all the same patterns hold true for the 2-fingered, but they do go poop a little more often (every 4 – 5 days on average) probably due to their slightly faster metabolism….

  7. bigjohn756
    Posted June 24, 2011 at 6:27 pm | Permalink

    I wanna be a baby sloth instead of the fat, old, sloth that I am.

  8. Tim Harris
    Posted June 24, 2011 at 6:51 pm | Permalink

    In Claude Levi-Strauss’s ‘The Jealous Potter’, there’s an interesting chapter – ‘The Sloth as a Cosmological Symbol’ – in which the sloth’s defecatory (?) habits, well-known to the Indians, whom L-S describes as ‘excellent naturalists’, are discussed. Worth reading.

  9. Felicia Marianadjá
    Posted June 25, 2011 at 1:46 am | Permalink

    They are so vulnerable when they are on the ground – makes sense that only the drive to reproduce would make that risk acceptable.

  10. Diane G.
    Posted June 25, 2011 at 2:20 am | Permalink

    Love the way the baby sloth she’s holding in the vid keeps trying to “climb” her.

    I got to hold a young sloth a few years ago in Costa Rica–a family seemed to be keeping it as a pet (and standing by the road, waiting for gringo tourists to come along)…It surprises me that such a solitary animal seems to so readily become ‘affectionate’ and ‘trusting’ with humans; I guess youthful dependence plays a part.

    Thanks for chiming in, Becky!

  11. Tim Harris
    Posted June 25, 2011 at 4:52 am | Permalink

    And in the connexion with Levi-Strauss’s remark about Native Americans being ‘excellent naturalists’, I do want to take issue – a bit! – with this from Jerry Coyne’s good take-down of Dr Bishop:

    7And tell me this, Dr. Bishop: if you were to get a bacterial infection, would you prefer to take an antibiotic or trust in the ministrations of a shaman? After all, both of those methods rely on “interpreted realities.”’

    I want to take issue with it, because it seems to me to represent an attitude that is common among among natural scientists who do not have much knowledge of anthropology and history (the same attitude appears every so often on PZ’s website). Yes, science is a wonderful thing, and I am not knocking it, but it simply is not the case that before the advent of modern science people lived totally benighted lives and relied, since they could rely on nothing else, on mere magic and wishful thinking. Jonathan Kingdon’s thought-provoking ‘Self-Made Man and His Undoing’ gives a good history of technological invention from humanity’s beginnings, and in his brilliant, illuminating and horrifying ‘War Before Civilization: The Myth of the Peaceful Savage’, the archaeologist Lawrence H. Keeley addresses the issue of the superiority of primitive practices where dealing with wounds to the common practices of 19th-century army surgeons, such as bleeding, the routine amputation of wounded limbs, the probing of wounds with unsterilised intruments, and the binding them tight with unsterilised bandages. ‘In comparison, most primitive healers merely extracted the projectile, sometimes bathed the wounds, and commonly covered them with poultices of plants known to have healing properties. A recent pharmacological study of over 2,000 plant extracts’ (used by primitive peoples) ‘found that 61 percent had some antibiotic effect…. Another shamanistic treatment, common at least in North America, involved sucking blood from the wound; where arrows were poisoned, this would have been a necessary precaution, but it would have helped to clean the wound in any case. The only surgical advantage that Western military doctors of the nineteenth century possessed over their primitive counterparts was their ability to stop massive bleeding from major arteries and veins. On the other hand, a number of prehistoric and recent chiefdoms practiced trepanation – removal of small pieces of skull to treat cranial fractures – an operation that Western surgeons did not master until the late nineteenth century. Archaeological finds of skulls with multiple healed terpanation scars indicate that this operation had a high rate of success. Thus shamanistic treatments were, in many cases, harmless at worst and very efficacious at best.’

    I am sorry about the length of this post, but I feel the matter is important. Sometimes, ready dismissals are justified, sometimes they are not.

  12. Tim Harris
    Posted June 25, 2011 at 4:54 am | Permalink

    I’m sorry also about the bad grammar and mistakes in places, but there’s no place to really see what one has written!

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