Orangs are herbivores? Think again.

January 17, 2012 • 11:35 am

From Matthew Cobb via Ed Yong, we have two orangs ripping apart and eating a slow loris.  Slow lorises comprise a group of strepsirrhine primates (the group that includes lemurs and lorises, as distinct from the haplorhine primates, comprising tarsiers, monkeys, and apes).  Orangs are, of course, supposed to be peaceful herbivores, subsisting mostly on fruits and leaves.

But as New Scientist reports (with this video), when plant food is scarce, Sumatran orangs (Pongo abelii; there are two species of orang, the other is the Bornean orang Pongo pygmaeus) hunt down one of the world’s cutest animals (made virally famous by the “tickled loris” YouTube vide0). Sporadic predation by orangs has been reported before, but the cases are accumulating, and actual hunting of other primates may be a culturally inherited behavior:

Madeleine Hardus of the University of Amsterdam in the Netherlands and colleagues have now observed three more cases, bringing the total to nine.

In 2007 Hardus was tracking two orangs in the canopy above her – a female called Yet and her infant Yeni – when Yet abruptly changed direction and approached a slow loris (Nycticebus coucang). She knocked it out of the tree, crashed down to the ground, bit the stunned loris’s head, then carried the body back into the tree to eat it. When Yeni begged, she was allowed to share the meat. The great apes each chomped on opposite ends of the dead primate, sharing it between them like lovers might a strand of spaghetti.

Searching through the scientific literature, Hardus found detailed studies of six orang-utan hunts. All stunned their prey before eating it, which Hardus thinks may be to avoid being bitten. Slow lorises are unique among primates in that their saliva is toxic.

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18 thoughts on “Orangs are herbivores? Think again.

    1. Interesting that we’ve had mention of toxic amphibians and toxic primates in the same day here. Frogs sequestering a toxin from something else sounded familiar, but I hadn’t heard about the loris toxin.

      Separate to your search, I found the Naturwissenschaften paper also cited in your link, and thought I’d mention that it seems to be a pair of disulfide-linked peptide chains and homolog of a feline allergen, which I guess might allow the occasional loris to slip in on a Caturday.

      1. I’m pretty sure my usage is fine. If you want me to acknowledge your pedantry try finding a citation that says otherwise.

  1. On one of the TV shows, an orang was running the lines of a native fisherman and eating the fish he had caught.

    I understand there are tiny snails on the vegetation gorillas eat and there is where they get B12, (is it?) anyway some vitamin that doesn’t occur in plants.

  2. Several new and somewhat puzzling things here.

    So how do the orangs avoid eating any of the toxins in the arm glands? Or is this something like rattlesnake venom? — you can ingest it, but it’s bad if injected into the blood stream via a bite.

    And, what do the loris do with it in their mouth? Is it used in defense against predators? Orangs specifically? Or is it to immobilize some prey item of theirs?

    What do the creationists think about all this? Does any of this seem like something a “god” would have designed? And, how long did it take to load the slow lorises onto the ark?

    1. I’ve heard that lorises will lick the poison onto their young to keep predators from eating them, and that they’ll also lick the poison before trying to bite. I don’t know how accurat

      1. Dang it, over sensitive touch-pad.

        “I don’t know how accurate that information is” is how that last sentence should have ended.

  3. I remain unimpressed. A few aberrant incidents does not a dietary classification make.

    Considering the pressures on Orangs now, I’m not shocked they might resort to this. Much as the Donner Party turned to cannibalism.

    Human cannibalism in various forms exists even today, so using the labeling as applied to Orangs here would mean humans would have to be listed as cannibals.

    You can’t play by two different sets of rules.

  4. Having recently come back from a year spent studying Sumatran Orangutans I can confirm that the reports of slow loris predation are robust and occur across their range, even in areas with high nutritional availability so don’t appear to correlate with lack of normal food sources. It does appear to be opportunistic though – I’m not aware of any reports of them going out and actively hunting them.
    The presence of poison in Slow Loris is slightly less sure – it makes a good story and has been widely reported but the initial data in support are not that impressive to me. They are very cute though…

  5. As an addendum to my previous comment the most likely reason for Orangutan carnivory is for the protein. The fruit, leaves, cambium, etc that make up the bulk of their diet is very low in protein and they eat a lot of termites and other insects as part of their normal diet and would certainly not turn away a nice concentrated protein source if it presented itself. Slow Loris are about the only thing in the jungle that can’t outrun an orang in the trees…

    1. I, for one, am certainly not surprised by their omnivory. Thank you for adding your research insights. I’ve learned to take anything New Scientist trumpets with a grain of salt, so independent confirmation is most welcome.

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