Tuesday, July 12, 2011

Smelly little messages

A gratuitous mongoose piccy.


Something slipped from my thermos flask and splashed into my mug of tea.

I didn't see it happen. I was sitting on a boulder, with one eye on my mongooses, pouring a quick cuppa while they searched for bugs.
But I heard the plop.

What the...?
Oh god!
Bobbing in my tea was a sticky, black mongoose poop nestled in a small plastic bag.

How did this happen?
Well, when I'm out in the field I carry two thermos flasks. One contains my morning brew and the other is filled with ice to keep faecal samples fresh and perky. Unfortunately, the two flasks look very much alike. And sometimes I'm just not paying attention as I stuff a sample into a flask...

As I carefully fished out the neatly labelled bag, I could see that the tea had seeped inside. Presumably, worse things had seeped out. I didn't know which aggrieved me more, the loss of my tea or the sample. You see, after five years working with dwarf mongooses I've come to share many of their perceptions of the world (scary, I know). And for a dwarf mongoose, every poop is sacred.

Unlike other family members, dwarf mongooses don't just broadcast their droppings far and wide. In fact, regardless of the leg-crossing involved, they'll only poop at the group's special scent-marking sites or at latrines located by each of their sleeping mounds. Now you may think the early morning rush to use the bathroom is hectic at your house, but it's nothing to the jostling that goes on when a mongoose group gets out of bed. Tumbling out of hole, they scramble and dash across to the latrine, a dozen little furry bodies jockeying for position all at one time. Even mongooses that don't need to go make a huge effort to squeeze something out. And once the group has headed off to forage, it's not unusual for someone to realise they haven't completed their toilette and, all in a panic, they'll go racing back. But why do they go to all this trouble?

Does scat mean scat? Latrines were once seen as Keep Out signs but, in many species, they're really community notice boards, all aflutter with phone-number fringed personal ads.
Image borrowed from here.

We know from experiments with banded mongooses and meerkats that mongooses can discriminate between the poop of different individuals. And not just their nearest and dearest; they can also tell the droppings of neighbours from those of strangers. And banded mongooses act very edgy indeed if they encounter a neighbour's poop steaming on the wrong border.

But how do they do it? Well like all carnivores (including Fido and Puss) mongooses are blessed with anal glands that secrete a fatty substance. This goo sits about cosily inside an anal pouch where it's feasted on by hungry bacteria. The bugs leave behind an array of volatile carboxylic acids (which stink), and which ones you end up with (and how much of each sort) depends on which types of bacteria are lurking in your anal pouch. Since every individual has its own unique bacterial assortment, everyone's acid profile is unique, and thus so is their pong. (I do have to wonder how antibiotics affects all this, for example in zoo animals.)

Comet leaving a message.

And of course excrement is also chockfull of all the hormones coursing through the depositor's veins. So for those with a sensitive nose, the gen is endless. Is he stressed? Is he feeling mean? Is she willing?

With so much personal information being bandied about, it's not surprising that individuals sometimes indulge in a bit of self promotion.
At meerkat latrines, the ladies post alluring come-hither messages for the guys next door while their male group-mates dash about madly, trying to mask these billets-doux with stinky macho threats. The end result is an absurdly male-biased latrine whose shitty composition bears no resemblance to the actual group make up.

The take away message proffered by a meerkat latrine.
Image borrowed from here.

In contrast to meerkats, banded mongooses are far more narcissistic. They consider poop an in-house affair. Everyone is too interested in getting the low down – or putting one over - their sexual rivals (who come from inside the group, not out) to spare much of a sniff for the leavings of the opposite sex.

But what are the dwarf mongooses up to? Why do they – unlike other mongooses – religiously pile up huge middens outside their sleeping dens? It's not as if dens (i.e. termite mounds) are in short supply; there are 200 to 300 in each group's territory (I know because I've plotted every one) and the group sleeps - and latrines - at only about 30.

It's in an attempt to figure out why my mongooses don't waste their waste that I daily risk the integrity of my morning cuppa. The smelly little samples I spoon up are destined for use in taste sniff tests. The idea is to present a smorgasbord of poo to selected individuals and see exactly what takes their fancy. Are they more intrigued by the droppings of outsiders or group members; rivals or lovers?

A mobile perfume counter. On the right are a male and female poop from the sniffer's own group; on the left they're from a strange group. Don't panic! The one in the middle isn't from a mongoose on steroids; it's an antelope turd, just to be sure they aren't simply attracted to anything that pongs.

My first attempt at this experiment was not a success.
In fact, it was one of those ghastly moments when you see your research career evaporating before your eyes.
No one sniffed anything.
They totally ignored every single dropping.

In desperation, I grabbed up a poop and stuffed it right under Pleiades' nose. She screwed her eyes shut and turned her head away with such overt revulsion I was shocked. I couldn't have evoked a more negative reaction if I'd done this to a human! I could almost see her thinking, 'Who would leave that here!'

That was when it hit me.

Dwarf mongooses never leave their droppings lying about in the field, yet here I was presenting samples to animals as they trotted about foraging. It was like tossing post-it notes under the feet of busy shoppers and wondering why no one read them.

I tried again at one of the group's scent-marking sites.
And low and behold, they scratched and sniffed!
O frabjous day!
Of course this makes the whole procedure much more tedious because the samples must be kept frozen until just before they're presented. So I spend my days trailing after the mongooses, trying to anticipate when they're going to stop in at one of their toilet facilities. When I believe a lavatory stop is imminent, I have to madly thaw the samples down the front of my shirt (and, yes, it does feel as ghastly as it sounds).

I'm still undertaking these trials so I can't yet tell you what messages are encrypted in my mongooses' latrines. However, it looks as if the ladies (who are very status conscious) are most interested in getting the low down on one another, while the guys can't resist a lovely female poop, particularly if it's from someone they haven't met.

Bugbears enjoying themselves at the information exchange (i.e. scent-marking site).

Saturday, July 2, 2011

Ware warthogs!

Photo by Arno Meintjes.

I’m writing this post for people, like myself, who felt irritated when the Lion King portrayed Pumbaa (the insouciant warthog) as living on bugs ('slimy... yet satisfying').

Alright, it was probably only me, but warthogs are grazers for Heaven’s sake!

Of the 16 pig species trotting about the world today, the warthog is the most deeply committed vegetarian.
And its veggie of choice is grass.

Look inside a warthog’s mouth and (if you can avoid losing a finger) you’ll discover a highly sophisticated grass processing plant. The incisors are designed for nipping shoots from closely cropped lawn, and behind the seriously off-putting canines (i.e. the tusks), the entire tooth row is given over to one mighty mother of a molar.
Young warthogs shed their normal piggy assemblage of premolars and molars so their third molar can grow to immense proportions. This behemoth, which is open-rooted and grows continuously, is designed to combat the gritty rasp of silica-rich grass. Even a warthog’s jaw hinges differently to that of other family members, allowing its chops to work up a good sideways swing for grass grinding.

Of course you may be wondering how such a specialised grass-muncher copes with the dry season when all the grass has withered away? Well hungry warthogs switch to rooting up the grass’s underground rhizomes and bulbs.

Now don’t get me wrong, although warthogs are connoisseurs of pasture they’ll also munch fruit and berries. But they have surprisingly conservative tastes; even when starving, they turn their snouts up at veggie scraps, apple peelings and bread (I’ll tell you about that fiasco some other time).

A warthog (Phacochoerus africanus) relishing a meal of marulas.
Photo by Brian Gratwicke.

But warthogs haven’t totally forgotten their omnivorous ancestry. This was brought home to me as I watched a large female warthog marching along a road in Kruger National Park. Up ahead, lying in the centre of the tarmac, was a road-killed squirrel.
‘Oh this will be interesting,’ I thought niavely, ‘I wonder if she’ll react?’
I imagined her pausing to give the little body a cursory sniff.

I was wrong.

As the warthog approached the body, she quickened her pace. And then, when she was still a meter away, she leapt. Yes, that’s right, leapt. It was a lightning fast strike and I gazed open-mouthed as she snatched up the dead squirrel and beat it viciously against the tarmac. I could hear the thwack, thwack, thwack from the car.
Moving at a frenzy, she hurled the squirrel high into the air and as it hit the ground she lunged forward and trampled on it, over and over, with her front trotters. It was like someone treading grapes, only ten times the speed. She repeated these manoeuvres like a creature possessed for some minutes and then, pinning the body with her front hoof, began tearing it apart.

I have to admit I was stunned. So much for darling little warthogs!

Cannibalism? No, a bit of hakuna matata; they’re grooming.
Photo by Arno & Louise Meintjes.

I was reminded of this illusion-shattering incident as I drove home from the mongooses earlier this week.
Now, I should explain that my landlord often sups on impala at his weekend braai (barbeque), and he tosses the less edible bits out for the delectation of the local vultures. So it’s not unusual for me to find myself engulfed in a flapping cloud of monstrous birds as I pass by on a Monday.

But this week the vultures weren’t enjoying their usual feast; they were all sitting waiting disconsolately in the trees.
Was a leopard keeping them off?
A lion...?

As I got nearer I saw that a warthog family was gathered at the carcass. This sounder (comprised of two big mums and nine piglets) is one of my favourites because the little hogs are always gambolling and jousting with one another or trotting along decorously - tails raised - in single file. But this week I was a little dismayed to see them tucking in enthusiastically at the bloody remains of the impala's ribcage. Each charming little piglet - its face spattered with gore - was tugging with great vigour on the end of a rib!

With my usual aplomb as a wildlife photographer, I failed to capture the moment (although you can see a camera-trap image of warthogs munching carrion here, if you need proof of this perfidy), and the best I can offer you are ‘after shots’.

The culprits fleeing the scene of the crime.

Pissed-off vultures (white-backed) waiting for the swine to relinquish their lunch.

So next time you’re watching the Lion King, be thankful that grass-eating Pumbaa is dining on nothing worse than bugs!
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