Science Spin May 2009

A morning with the meerkats

5:00 am

The alarm clock is ringing. It's still dark outside. I get up, take my backpack; quick check: GPS, aerial antenna, scales, data logger...it's all in there. Walking to the field station from my cabin, I scare a resident porcupine who rushes into the dark. He's been at it again, digging around a large acacia tree next to the 'farmhouse' where the field station is based. I hop over the hole it dug and enter the farmhouse.

The eggs are already boiling in the kitchen. Three, four, five... I put an extra one in: the resident volunteers don't always put the eggs in for us visiting researchers. I take my cereal bowl and squeeze between two Earthwatchers on the worn-out sofa in the living/dining room, the main social space at the field station. "So, which group are you going to today?" I mumble, still half-asleep. Earthwatchers pay a lot of money to visit and take part in research on the wild meerkats of the Kalahari Meerkat Project.

The Project was set up by the University of Cambridge and has been running ever since with the help of volunteers who come mainly from UK and Australia. Volunteers stay for a year collecting daily detailed data about all aspects of the lives of several groups of meerkats. They collect background data using the ad libitum method, which means they observe the whole group and record any interesting events that occur. These may include the cooperative behaviours that meerkats are most famous for: pup-feeding, babysitting, sentinel behaviour, burrow maintenance (social digging) or allo-grooming (grooming each other). On a more exciting day they will record group battles they refer to as inter-group interactions or 'iggys', predation attempts by raptor birds, or a roving meerkat from another group trying to mate with the resident females.

Meerkats (Suricata suricatta) are small, carnivorous mammals weighing on average less than 1 kilogram. They inhabit the arid areas of southern Africa and live in social groups of 2-50 individuals, consisting of one dominant pair and a variable number of related and unrelated subordinate helpers. They are an excellent model species for studying behavioural biology and ecology because they can be habituated to close observation by humans; they are also diurnal and forage in a relatively open habitat and are hence easy to follow and observe on foot. The aspect of their lives that interests evolutionary biologists the most is their sociality. Why do they live in groups? Why do the young adults stay in the group and why do they help each other? What are the evolutionary conflicts among individuals living in groups and how are these resolved?

For meerkats, group living makes sense because there is little available land for establishing their own territories, and the harsh desert environment makes it difficult to survive alone. All adult meerkats contribute to cooperative behaviours, the main ones being pup-feeding, sentinel duty, burrow maintenance and for females allo-lactation (lactating for another meerkat's pups). Co-operation increases the pups' survival, development and subsequent reproductive success, which benefits the group as a whole, because larger groups are more likely to survive.

A meerkat usually has to worry about two main things in life: "Find food. Avoid being eaten yourself".

Birds of prey, wild cats, jackals, snakes...if it's bigger than a meerkat and if it eats meat, it's probably a threat. Living in a group is an advantage; many eyes see better. But meerkats have evolved an even more sophisticated strategy to avoid predation: posting sentinels, usually one but sometimes several at the time. Like soldiers on guard, meerkat sentinels scan the horizon from an elevated post and announce their duty with a special sentinel call, the 'watchman's song'. They have excellent depth perception that allows them to detect predators at a great distance. Having a sentinel on guard reduces the possibility of a surprise attack and this allows the rest of the group to be less vigilant.

Having followed these meerkats for over a decade means that researchers know exactly where their territories are, which sleeping burrows they use and the relationships that individual meerkats have within their group.

5:30 a.m.

I start my car, but forget to check where my group went down to sleep last night: quick run to the farmhouse to check the co-ordinates of the sleeping burrow on the wall sheet containing latest positions of all groups. "RB101, where the heck is that?!" As the dry season has lasted for longer than usual, the meerkats are struggling to find food at their regular foraging spots and some groups are moving to rarely used parts of their territories in search of insects and other arthropods, their main diet. Quick look at the map and my GPS to make sure I have the co-ordinates of this burrow and I'm off.

The sun is already rising behind the sand dunes on the horizon. Driving along the narrow sand road I startle a herd of 20 or so wildebeests that were grazing around a water hole. They are lovely animals, much friendlier than some of the other large antelopes at the Project. My colleague Matt is lucky to be alive after surprise attack by a semi-tame eland. It's funny to think that while this Project was still being set up, the Gemsbok National Park researchers had to look out for lions while observing meerkats; it seems dangerous enough with the violent antelopes and horny, testosterone-crazed male ostriches that sometimes charge us here at the ranch.

5:55 a.m.

I park my car under a tree and check my GPS. Another 800 metres to walk before I reach the burrow. I'd better hurry: meerkats usually get up at sunrise during the summer months and they only spend short periods sun-bathing and grooming each other before heading off to forage. That doesn't leave me much time to weigh all 25 of them. Weight is used to estimate the meerkats' foraging efficiency and physical condition, which are then used in most statistical analyses in studies on their behaviour. Some meerkats contribute a lot to co-operative behaviours, others don't: what is causing this variation? Does it depend on their physical condition, hormonal levels, or status within the group? Or could we say meerkats have different personalities, like people? I wonder about this as I stumble upon the sleeping burrow. "Good, they're not up yet." This gives me a bit of time to enjoy the scenery, dusty sand dunes with patches of dry grass, scattered with green acacia trees and occasional group of springbok - small colourful antelopes grazing under the trees.

Kalahari Meerkat Project was set up some 15 years ago by Professor Clutton-Brock from University of Cambridge. In the meantime various collaborations have been fostered, especially with University of Zurich in Switzerland and Pretoria University in South Africa. All meerkats at the project are wild but habituated to people and are easily identifiable by small dye marks painted on them by the researchers and volunteers. These dye marks make for an easy ID check as "head and shoulders" is different from "right rib, right thigh". Volunteers who spend a year at the project collect various background data on meerkats (collect their weights, mark who the first to get up and last to go to sleeping burrow is, track their use of different burrow etc.) and make sure all the meerkats are habituated. Since most meerkats are followed from birth their parents are known as well as their whole life-history. Used to people since birth they ignore us so we can observe them from up to 0.5 m away and walk among the group without disturbing their normal behaviour.

The project manager makes a weekly schedule of group visits to allow researchers (masters and PhD students and postdocs) to visit the groups they need for their experiments and to make sure all group are visited at least a couple of times a week by volunteers to keep track of where they go and what they do. In every group one animal has a radio collar that allows us to track them down; also most of their sleeping burrows are labelled with GPS points so it is easy to locate them. All pups are caught and inserted under their skin with an ID microchip in case the dye marks on their fur wear out. Their blood samples are also taken at regular intervals in their lives, both to get their DNA profile and hormonal profile. This helps researchers to determine relationships within and between the groups and to correlate behaviours to hormones. These captures take only a few minutes to avoid stressing the animals too much.

Researching meerkats involves waking up before sunrise to arrive at the sleeping burrow before meerkats get up. Various records have to be kept such as where they slept, when they got up, how heavy they were (we use small crumbs of hard-boiled egg to lure them onto scales saying "yum, yum yum!"), count and identify them all to check group's composition and then follow them for three hours while they forage for food and avoid predators. When following them we also take regular GPS readings to get the routes meerkats take on their foraging trips. At midday when meerkats have a siesta to avoid the heat of the desert sun we leave to have lunch and return in the afternoon for more data collection. Experiments we do might include playback of their own vocalizations or presentations of predator cues or faeces to observe their response to those.

7:10 a.m.

"Yum, yum, yum, yum..." I tempt another scurry with a bit of hard-boiled egg, their favourite fast-food. "There you go. Wow, you've lost a lot of weight since last night!" I keep talking to the meerkat as I jot its weight down in the notebook. As I do this an 'egg-monster' jumps in and pushes its brother out of the scales' box. Weighing is the most intimate and enjoyable time a researcher gets with meerkats; yet it can get irritating. Some meerkats simply refuse to enter the scales and jump straight out when picked up by their tail and placed there; others are egg-monsters, so hooked on hard-boiled egg crumbs that they keep jumping into the scales and disrupt the weighing of the others. They do this especially in the morning when they emerge from the burrow famished, having used lots of energy and lost up to 10 per cent of their body mass as they huddled together to keep warm during the long, cold desert nights. As much as I feel sorry for them, especially the small meerkat that was born without claws and so it finds digging for food in the tough, sun-baked sand difficult, I cannot give them more egg than is necessary to weigh them. As researchers we observe the meerkats but try not to interfere with their lives too much: we even leave pups to die if their group mistakenly leaves them at the wrong burrow. Some find this disgraceful; others accept it as part of the work bioethics. Who is right? I don't know, but I can see both sides and accept that work with wild animals inevitably invokes such dilemmas. I comfort myself with the thought that my work might at least help provide captive meerkats with better sentinel posts; knowledge of their wild behaviour and natural preferences for choice of sentinel posts may inform how best to keep them happy in captivity.

Today is a presentation experiment day: I am presenting a foreign meerkat's faeces to this group to see how they react to it. My working hypothesis is that a smell from a foreign group will increase this group's sentinel efforts: if there is a foreign group around, it's best to spot them before they spot you. Meerkats are not good neighbours. When they encounter other groups, they do a 'war dance' and attempt to intimidate the rivals before engaging in bloody battles that may leave injured and dead meerkats on both sides. It's not just in their co-operative behaviours that they are similar to people.

8:45 a.m.

"I'll have to put my name down on rota for next week so that I can do a playback experiment with this group," I think to myself as I unpack the frozen faeces to present to the group. Suddenly, I hear a sentinel barking from the top of a nearby bush and the whole group runs off in opposite direction. Struggling to keep up without scaring them as I run after them through the tall, dry sour-grass, I lose the group. Not the best start to the day.

Luckily each group has one individual equipped with a radio collar so they can easily be tracked from up to a kilometre away. Today, though, the group saw something, perhaps a caracal, a medium-sized wild cat, that scared them and they ran a fair distance, leaving me to waste most of the morning tracking them down again. When I finally find them they are already 'crashed-out' around one of their sleeping burrows. Meerkats are especially renowned for taking siestas at unseemly times of the day, disrupting even the experienced researchers' experiment plans. A few of them are below the ground, two pups are play-fighting and the dominant female is grooming the dominant male. It's a bit late to do the experiment now, since the plan was to observe their behaviour while they foraged. It's one lesson any zoologist learns soon enough: even the best planned experiment will only come to pass if the animals allow it.