Meerkat superheroes

Flower is an internationallyacclaimed television star. The

Discovery Channel’s series MeerkatManor, the first ‘animal Big Brother’show, made her cute little face popu-lar around the globe. Now a feature-length biography has also beenreleased with an accompanying book,Meerkat Manor: The Story of Flower ofthe Kalahari.

Flower’s story only reached theworld because of the research effortsof scientists based at the University ofCambridge, UK, who set up theKalahari Meerkat Projectw1 15 yearsago and have studied the lives of sev-eral meerkat groups daily ever since.Such long-term field projects havebecome popular in the field of behav-ioural biology because they permitthe accumulation of an enormousamount of data on every aspect ofanimals’ lives, allowing scientists toask and answer ever-more detailedquestions about their evolution.

When not on camera, Flower, likeother meerkats (Suricata suricatta), hasto worry about two main things inlife: finding food, and avoiding beingeaten herself. When the right time(and the right male) comes, a third

worry comes into her head: reproduc-ing. Such is the nature of naturalselection: only those who survivelong enough to reproduce will spreadtheir genes to the next generation.Flower is a descendent of a long lineof survivors. This means she hasadaptations that allow her to survivedespite the many predatory speciesout to get her.

Birds of prey, wild cats, jackals,snakes.... If it’s bigger than a meerkatand it eats meat, it’s probably a threat.Living in a group is an advantage;many eyes see better. But meerkatshave evolved an even more sophisti-cated strategy to avoid predation:posting sentinelsw2, usually one butsometimes several at the time. Likesoldiers on guard, meerkat sentinelsscan the horizon from an elevatedpost and announce their duty with aspecial sentinel call, the ‘watchman’ssong’. They have excellent depth per-ception that allows them to see preda-tors at a great distance. Having a sen-tinel on guard reduces the possibilityof surprise attacks and allows the restof the group to be less vigilant.

Sentinel behaviour may seem altru-istic since the sentinels help others at

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Sentinels: meerkat superheroesMico Tatalovic from the University of Cambridge, UK,investigates the private lives of meerkats. Why do thesesmall carnivores live in groups? Why do they feed eachother’s pups, dig together and guard each other? Andwhat makes a really good sentinel?

Science in School Issue 10 : Winter 2008

Image courtesy of M

ico Tatalovic

Meerkats sunning themselves.Especially in winter months, meerkats

sun themselves to warm up in themorning before foraging, and in the

evening before going to sleep

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Meerkat researchThe Kalahari Meerkat Project was set up some 15 yearsago by Professor Clutton-Brock from the University ofCambridge, UK. Since then, the Cambridge scientists havecollaborated with colleagues in other countries, especial-ly at the University of Zurich in Switzerland and PretoriaUniversity in South Africa.

All meerkats involved in the project are wild but habituat-ed to people and are easily identifiable by small dye marksthat the researchers and volunteers have painted on them.These dye marks make for easy identification, as ‘head andshoulders’ is different from ‘right rib, right thigh’. Familiarwith people since birth, the animals ignore us so we canobserve them from as little as 0.5 m away and walk amongthe group without disturbing their normal behaviour. Sincemost meerkats are studied from birth, each individual’sparentage and life history is recorded.

The project manager makes a weekly schedule of groupvisits to allow researchers (master’s students, PhD studentsand postdoctoral researchers) to visit the meerkat groupsthey need for their experiments and to make sure allgroups are visited at least a couple of times a week by vol-unteers to keep track of where the animals go and whatthey do. In every group, one animal has a radio collar thatallows it to be tracked; most of their sleeping burrows arealso labelled with GPS points so it is easy to locate them.

All pups are caught and an identity microchip is insertedunder their skin in case the dye marks on their fur wearout. Blood samples are also taken at regular intervalsthroughout their lives, to obtain both their DNA and hor-monal profiles. This helps researchers to determine rela-tionships within and between the groups and to correlatebehaviours with hormone levels. The animals are capturedfor only a few minutes, to avoid stressing them too much.

For the scientists, a typical day of meerkat researchinvolves waking up before sunrise to arrive at the sleepingburrow before meerkats get up. Various records have to bekept, such as where the animals slept, when they got up,how heavy they are (we use small crumbs of hard-boiledegg to lure them onto scales, saying “yum, yum, yum!”).We also count and identify all the animals to check thegroup’s composition and then follow them for three hourswhile they forage for food and avoid predators. When fol-lowing them, we also take regular GPS readings to calcu-late the routes that the meerkats take on their foragingtrips. At midday, when the meerkats have a siesta to avoidthe heat of the desert sun, we leave to have lunch andreturn in the afternoon for more data collection. Afternoonexperiments might include playing the meerkats’ ownvocalisations back to them or presenting them with pred-ator cues or faeces to observe their responses.B

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Meerkats resting. In the summer months,meerkats rest at middayto avoid the heat

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their own expense: when they areguarding, they not only expend energyand lose valuable foraging time, butalso expose themselves to predators.But are they really being altruistic?

My research group investigates con-flicts and co-operation in meerkatsocieties, and as part of this work, Ifocus on sentinels. One of the mainquestions I am investigating is whysome meerkats spend more time onguard than others. An answer to asimple question like this can give usvaluable insights into the evolution ofsocial behaviour. ‘Why are somehumans more social than others?’ and‘How did our sense of communityand helping others initially evolve?’we may ask eventually. Until then, westudy model animals, such as

meerkats, to give us preliminaryanswers and to help us formulate andtest theories.

Flower keeps guard from trees,logs, bushes, grass tufts or evenhuman heads. The average height ofthe posts from which meerkats keepguard is around 60 cm although thebravest sentinels will climb trees upto six metres high. The height of thesentinel’s post also varies with thevegetation cover; during the rainyseason when grass is tall, sentinelsguard from higher posts so that theycan see above the grass. This reflectsthe fact that the behaviour of wildanimals is affected by their environ-ment; when studying behaviour, it isoften important to consider the envi-ronmental effects.

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Meerkat societyMeerkats (Suricata suricatta) are small, carnivorousmammals weighing on average less than one kilogram.They inhabit the arid areas of southern Africa and live insocial groups of 2-50 individuals, consisting of one dom-inant pair and a variable number of subordinate helperswho may or may not be related to the dominant pair.These members of the mongoose family (Herpestidae)eat mainly arthropods (insects, spiders and their rela-tives), as well as the occasional small mammal, reptile orplant bulb.

They have territories with several sleeping burrows, fromwhich they make daily foraging trips of up to a few kilo-metres. Depending on food availability and predationpressure at specific spots, they will either return to thesame sleeping burrow for several nights, or change bur-rows quite frequently.

On average, litters consist of three to four pups that staywithin the burrow until they are approximately threeweeks old. During that time, while the pups are beingfed on milk, the group returns to the same burrow. Atfour weeks of age, the pups begin travelling with thegroup and for their first three months of life, are fed oninvertebrates and small vertebrates by helpers.

Meerkats reach adulthood at around one year of age. Ataround 18-30 months of age, males voluntarily leave thegroup, either to join an existing group or to form a newgroup with unrelated females. Adult females, particular-ly pregnant ones, may be evicted from their home groupby the pregnant dominant female; this is thought toreduce the chance of the dominant female’s pups beingeaten by the other females. Most females return to thegroup once the dominant female has given birth, butsome may permanently disperse to form new groupswith unrelated males.

Dominant meerkats live for 6-10 years on average, withthe oldest individual in the Kalahari Meerkat Projectbeing almost 13 years. The age of subordinate meerkatsis more difficult to record, as many disperse or are evicted by the age of around three years, and are subse-quently lost to the project records. The most importantknown causes of death are predation, fights with othermeerkats (including infanticide), diseases and human-caused factors such as car fatalities – but for two-thirdsof the Kalahari Meerkat Project meerkats, the cause ofdeath is unknown, since the individuals just disap-peared.B

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Meerkats at a sleeping burrow. Sleepingburrows may have several exits androoms inside. Meerkats maintain thembut don’t dig them; instead they useground squirrels’ burrows and sometimesalso share them with yellow mongoosesthat live in small family groups

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Sentinel behaviour also differsbetween individual meerkats. Somesentinels will go on guard more often,and guard longer and from higherposts: this is why we consider them tobe ‘supersentinels’ – although wedon’t actually know if these individu-als are also the most efficient indetecting predators. The longer theystay on guard, the more likely theyare to announce their alertness whenprotecting the group, so that thegroup can relax. Supersentinels arealso likely to be animals that are usu-ally more vigilant; even when theyare not on sentinel duty, they oftenstop while foraging for food to briefly

check the surroundings for anythingsuspicious. It seems that these super-sentinels also have higher levels ofthe stress hormone cortisol. This rais-es the question of whether this hor-mone is the cause or the effect of theirbehaviour. Future research couldaddress this by observing how an

increase or decrease in cortisol levels– by introducing the hormone into theanimal’s system or blocking it throughthe introduction of another molecule– changes meerkats’ behaviour.

But why do we devote so muchtime to elucidating meerkat behav-iour? Studying specific behaviourssuch as guarding is like fitting a sin-gle piece of puzzle into the larger pic-ture of the evolution of social behav-iour. Eventually we would like tounderstand how, why and when co-


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Meerkats are an excellent model species for studying behav-ioural biology and ecology because they can be habituatedto close observation by humans; they are also diurnal andforage in a relatively open habitat and are hence easy to fol-low and observe on foot. The aspect of their lives that inter-ests evolutionary biologists the most is their sociality. Whydo they live in groups? Why do the young adults stay in thegroup and why do they help each other? What are the evo-lutionary conflicts among individuals living in groups andhow are these resolved?

Benefits of group living

For meerkats, group living makes sense because there is little available land for establishing their own territories,most of the appropriate habitat having already been takenby rival groups, and the harsh desert environment makes itdifficult to survive alone. All adult meerkats contribute toco-operative behaviours; the main ones are pup feeding,sentinel duty, burrow maintenance and, for females, allolac-tation (lactating for another meerkat’s pups). Co-operationincreases the pups’ survival, development and subsequentreproductive success, which benefits the group as a whole,because larger groups are more likely to survive.

Costs of group living

There is a trade-off for individuals between the benefits andcosts of group living. One of the main costs of group livingis the prevention of reproduction: the dominant breedingpair accounts for around 80% of the offspring born to thegroup. Dominant females try to weight the reproduction intheir own favour, so that they produce as many offspring aspossible; subordinate females are commonly expelled fromthe group by the dominant female in the latter half of herpregnancy to prevent infanticide by subordinates.Subordinate females are also evolutionarily driven to repro-duce, in spite of attempts by the dominant female to preventthis from happening. Similarly, subordinate males try to findreceptive females from neighbouring groups and thusenhance their reproductive success.

The exact nature of these within- and between-group con-flicts and resolutions is a subject of continuing research.Currently, scientists are looking at the way in which differ-ent hormones such as oxytocin (the ‘trust’ hormone) affectsocial behaviour and conflicts within the group. Others areexamining the influence of an individual meerkat’s person-ality on its behaviour and decisions.

Meerkat guardingfrom the top of adry branch

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Science in School Issue 10 : Winter 2008


operation evolved in animals and inour own species. We would like toknow why we are so different fromother animals. We would like to probedeeper into the evolution of life onour planet and to satisfy our thirstycuriosity. “Why?” It’s the questionthat drives science.

Meerkats are an excellent modelsystem to test hypotheses arisingfrom the theory of evolution. One ofthe biggest unsolved problems in evo-

lutionary biology is the existence ofaltruistic behaviours in humans andanimals. Darwin’s theory of naturalselection argues for the survival of thefittest through competition for limitedresources (food, mates, space). Yet, wefind animals such as meerkats co-operating happily; they baby-sit andfeed (even lactate for) other meerkat’spups, dig burrows together andguard the whole group from predatorattacks. How can Darwin’s theoryexplain the observed harmoniouslives of meerkats?

After 15 years of detailed study ofmeerkats, Professor Tim Clutton-Brock

w3of Cambridge University and

his colleagues say that meerkats arenot that altruistic after all. There is alot of selfish behaviour going on. Aclassic example, published in the jour-nal Science, is the finding that meerkatsentinels guard from safe sites, andonly once their bellies are full(Clutton-Brock et al, 1999). Moreover,being the first to spot predatorsmeans that in most cases they are thefirst to escape them too. This suggeststhat direct, selfish benefits are the

main causes of the evolution of thissocial, apparently altruistic behaviour.However, we still don’t know exactlywhy meerkats guard and why someare just so super at it. The currenthypothesis is that good foragers –meerkats that are the most efficient atcapturing prey – are also the best sen-tinels, because they spend less timeforaging and thus have more timeand energy to spend on other activi-ties. But the evidence is still too scarceto support this. My research mighthelp elucidate some of the answers tothese questions. I just hope they’renot doing it only for the cameras!

ReferencesClutton-Brock TH et al (1999) Selfish

sentinels in cooperative mammals.Science 284: 1640-1644. doi:10.1126/science.284.5420.1640

Web referencesw1 – For more information about the

Kalahari Meerkat Project see:www.kalahari-meerkats.com

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Meerkats sunningthemselves

Meerkats emerging from a bolthole aftera predator alarm

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www.scienceinschool.org 25Science in School Issue 10 : Winter 2008

This article provides some basic information aboutmeerkats and addresses various aspects of their socialbehaviour, with an emphasis on the sentinels. The arti-cle is interesting, sometimes even humorous, just likethe animals it talks about. It makes good material fordiscussions/debates on issues such as the evolution ofco-operation in animals and in humans, and how ani-mal and human altruism compare and contrast. Theissue of social behaviour also creates the opportunityfor interdisciplinary studies.

The article could give rise to many comprehensionquestions, including:

1. Why do researchers consider meerkats to beexcellent model species for studying behaviouralbiology and ecology?

2. What are the benefits and the costs of group livingfor meerkats?

3. Why does Professor Tim Clutton-Brock say thatmeerkats are not altruistic?

4. Which main co-operative behaviours do adultmeerkats contribute to?

5. How does the height of the sentinel’s post varyaccording to the environmental conditions presentat the time?

6. Why are meerkats considered an excellent studysystem to test hypotheses arising from the theoryof evolution?

Michalis Hadjimarcou, Cyprus

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Mobbing a snake:Mobbing is used to gatherinformation about a threatand to chase off potentialpredators

w2 – To watch a video clip of meerkatsentinels on the Discovery Channelwebsite, see:http://animal.discovery.com/fansites/meerkat/video/video.html(note that you may have to watchan advertisement before the videoclip appears)

w3 – For more information about thework of Tim Clutton-Brock’sresearch group, see:www.zoo.cam.ac.uk/zoostaff/larg/Pages/

ResourcesFor more information about meerkats,

see:

The Fellow Earthlings’ WildlifeCenter, which specialises in caringfor meerkats: www.fellowearthlings.org

The East Coast Meerkat Society:www.meerkatsrule.org

Mico Tatalovic is studying for amaster’s degree (MPhil) in theDepartment of Zoology at theUniversity of Cambridge, UK.Originally from Croatia, he wasawarded a scholarship, first to studyat the University of Oxford, UK, andthen at Cambridge.

Image courtesy of Eleanor Harris


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Meerkat superheroes