Saturday, 10 November 2012

Toe-biting Possums

Many brushtail possums have a toe-biting habit. When I was on holidays in Tasmania a few years ago, one of the local possums (named Rufus) greeted me in the following way:

Rufus toe-biting - Cradle Mountain, Tasmania 8/9/2008

I haven't worked out what the motivation for this is.

The majority will advance menacingly towards a person's foot, lightly nip at the big toe then run away. Some, however, will merely sniff at a toe. Very few will bite hard. Some possums never toe-bite at all. Ginger, our first possum, was like this. She would occasionally climb a person's leg, but never toe-bite.

Here's Kiki getting in a bit of a nip recently.

Kiki Toe-biting 31/10/2012

Here's Fifi and Svejk (as a baby) gently nibbling toes. They seem more curious than anything.

Fifi Toe-biting 30/11/2009

Svejk Toe-biting 7/5/2007 [Photo by Xesce]

Zorba, on the other hand, is a little more fierce.

Zorba Toe-biting 11/12/2010

Whereas Leena (who was otherwise always gentle and good-natured towards humans) looks absolutely crazed.

Leena Toe-biting 26/2/2009

Leena Toe-biting 26/2/2009
Toe biting is a well known phenomenon amongst brushtails. You will frequently see mentions of it on the web, such as this and this.

Mike Archer (who was at the time head of the Australian Museum in Canberra) mentioned the following in an article which explored (amongst other things) the idea of keeping Australian wildlife as pets:

"Although I have also had Swamp Wallabies (Wallabia bicolor), Nailtail Wallabies (Onychogalea unguifera), Rufous Bettongs (Bettongia rufescens) and Brushtail Possums (Trichosurus vulpecula) as house companions, each had a downside. [...] Brushtail Possums, while great as youngsters, could not resist nibbling toes when they became adult. Each, however, would have been fine in large, suitable backyards, or as visitors in the house, able to live outside."
Incidentally, this article is interesting and thought-provoking and worth a read if you're interested in conservation.

An information leaflet from Magnetic Island suggests (but without providing any evidence) that toe-biting is a begging behavior.

"Some Magnetic Island possums, if used to humans, have a particular 'toe biting' behaviour. If a possum approaches your bare, sandled or thonged feet it is best to back off as they may gently or not so gently bite the big toe. It is a behaviour associated with begging and it is best not to encouraged [sic] as they may break the skin."

This explanation makes sense to a degree. Possums in city parks will often menace people in this way to extort food off them. However, I don't think this is the full story; possums also seem to toe-bite in situations where there is no food reward for doing so.

For instance, a guy in New Zealand relates a humorous story 

In brief, a possum was entering the kitchen of one his friends at night to nibble on fruit. As this was in New Zealand where the brushtail possum is an introduced pest, he planned to capture (and apparently kill) this possum and therefore bunked down on a nearby couch to wait in ambush.

The cheeky possum then entered the kitchen again, and, rather than dining on fruit, sneaked up on the guy from behind and bit him hard on the toe.

I'm glad to report that the possum escaped death and in the end was merely flung out of the door into the night.

Anyway, the point is that it's very hard to reconcile this story with the theory that toe-biting is a begging behavior.

2 comments:

  1. I'd appreciate any further information you've gathered about biting behaviour. I have a possum raised from a baby because it's mum died on the road. We're been really good friends. Her release has been gradual and at this point I'm still feeding her a little most nights. She's happy to sit on me and be fed, until recently she'd lick my beard during feeding, I guess both grooming and getting crumbs of food and she's recently started rubbing her chest on me, which I gather is a scent spreading behaviour. What's driving me crazy is she now also jumps out at me and sinks teeth and claws into my leg. They're really sharp and it really hurts and I'm a fairly tough bloke but getting some firewood at night is terrifying now. I think she's playing. When she was little I used to play with her by scratching my nails along the branches in her enclosure which she'd chase after and bite softly. She seems to get excited by the sound of my feet in leaf litter. I guess she may be trying to chase me out of her territory. A couple nights ago I gave her a good kick and I'm feeling pretty guilty about that.

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    Replies
    1. First of all, you have my admiration for raising and soft-releasing a possum. I haven't had to do that and I would be scared that the possum would be chased off by resident possums before it had time to adapt to being in the wild.

      Unfortunately, I haven't gained any further insights into toe-biting since writing that post.

      It seems to be an innate behaviour for most brushtails to approach a person's toes in a menacing manner, but usually they only give a light nip and then run away. Sometimes the possum will just hold the toe in its mouth without biting; it's as if the possum has an instinct to go after toes, but then doesn't know quite what do when it catches one.

      I have never had a possum sink claws into a leg. One possum (Ginger) would climb my leg, but I was always wearing jeans and there was little or no prickling from the claws; she didn't sink them in.

      I would think that your possum is probably playing roughly. The closest I've seen to this behaviour is that some possums will swipe with their claws when offered food by hand; usually possums do this when angry or impatient, but a few seem to do it just for fun. It seems that possum skin is much tougher than human skin - I've seen possums with no visible wounds after a fight that would definitely have drawn blood from a human - so maybe they underestimate the damage their claws can do to human skin.

      There are various animal training techniques that people to curb undesirable behaviour in pets (I have seen the book "Don't Shoot The Dog" by Karen Pryor, which has a lot of ideas), but it's not clear how easy they would be to apply to a wild-living animal. And brushtails are very independent creatures and probably more like a cat than a dog when it comes to training.

      I suppose you could always wear cricket pads when getting firewood. :)

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