Like humans, elephants live in a complex fission-fusion society (Image: FLPA)
Behind every successful elephant dynasty you’ll find a wise old matriarch. What does it take to lead the herd?
ELEANOR was nearly 50 when she collapsed and died. While African elephants can live up to 70 years, female life expectancy is just 22 in her group in Samburu, Kenya, and Eleanor was the oldest member of her family – the matriarch. . For almost a week after her death her carcass was visited not just by members of her immediate family, but by a succession of animals from four unrelated families. Elephants are mysteriously curious about death, a response perhaps heightened when a leader dies.
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It has long been clear that elephant groups rely on their elder stateswomen, but just how important these females are is only gradually becoming apparent. Matriarchs are at the hub of a complex, multilayered social network, and we are now getting insights into the nature of the ties that bind these close-knit groups and the key role that wise old leaders play in enhancing the survival of their members. Matriarchs carry with them a treasure trove of crucial information. They have a unique influence over group decision-making. And, like our own leaders, the most successful may even possess certain personality traits.
“Matriarchs carry a treasure trove of crucial information and have a unique influence over their group”
Much of what we know about elephant social life comes from research done at Amboseli National Park in Kenya, where the population lives in conditions close to a natural, undisturbed state. But this is unusual. Across Africa elephant numbers are dwindling as demand for ivory has surged in recent years. On the black market, a pair of tusks can fetch the equivalent of 15 years of an unskilled worker’s salary, so the incentive for poachers is high. Once poachers have killed the biggest males, mature matriarchs are their next targets. What happens to a group that loses its matriarch is not clear. But one thing is certain; if we want to help elephants we need to understand the structure and function of leadership within their society.
Amboseli’s elephants number around 1400. They roam over approximately 8000 square kilometres, inside and outside the park, and across international boundaries. With Mount Kilimanjaro towering in the distance, this is a region constantly in flux, which has big effects on its residents. For elephants, which must drink every day, access to water is the biggest issue. Although there are predictable wet and dry seasons, sometimes the rains fail. And seismic wobbles alter the flow and salinity of underground rivers feeding the springs and swamps on which elephants depend.
These are the world’s longest studied elephants. Every individual is known and visually catalogued by distinct ear notches. And nobody knows them better than Cynthia Moss, who has led the Amboseli Elephant Research Project (AERP) since she founded it in 1972. After four decades of near-continuous observation of elephants going about their daily lives, she has a vast knowledge. In particular, Moss and her colleagues have discovered much about elephant families and their social interactions. “Our studies show how absolutely crucial matriarchs are to the well-being and success of the family,” she says.
At Amboseli, the elephant family unit, consisting of a mother and her immature young, sometimes along with sisters, aunts and grandmothers, is the core of elephant society. Within family groups, which range in size from two to more than 20, the oldest, most experienced female takes the lead. But group size is constantly changing, responding to the seasons, the availability of food and water, and the threat from predators. An adult female elephant might start the day feeding with 12 to 15 individuals, be part of a group of 25 by mid-morning, and 100 at midday, then go back to a family of 12 in the afternoon, and finally settle for the night with just her dependent offspring. Known as a fission-fusion society, it is a complex social dynamic relatively rare in the animal kingdom, but not uncommon in primates, including humans.
Friends and relations
It has long been assumed that the structure of the wider social network grows out of natural patterns of mother-offspring associations, where daughters remain within their group for life, while sons strike out on their own as teenagers. A team led by Beth Archie from Duke University in Durham, North Carolina, decided to test this idea. By genetically analysing faecal and tissue samples from 236 elephants at Amboseli, they determined how closely related they were to each other, and then superimposed the familial ties onto observed patterns of association. They found a remarkable fit, indicating that the fission-fusion dynamic mirrors relatedness – the more closely related individuals are, the more time they tend to spend with one another ().
So, at Amboseli at least, a matriarch heads up a group of her immediate relatives and the social network extends beyond this core family unit. Multiple families that engage in regular friendly associations, including ceremonial greeting and touching, are known as bond groups. These multifamily groupings can reach 70 to 100, but have historically averaged about 30 at Amboseli. Networks of elephants can reach further still, to include friendships between unrelated individuals, and less frequent aggregations of families known as clans, which when together can reach numbers in the hundreds.
To investigate the dynamics of multi-tiered elephant social networks from the level of family to the population level, Moss, together with Vicki Fishlock, a resident scientist with the AERP, and Phyllis Lee from the University of Stirling, UK, are using a computer model to generate spiderweb-like “sociograms” indicating the extent and strength of associations. Analysing sightings of 31 families seen more than 500 times over four decades, they have found something remarkable. While average family size has grown considerably, from 7 in the 1970s to 22 by 2011, families have become less cohesive, and spend less time associating with other families.
Mama knows best
Amboseli is an undisturbed population, so habitat fragmentation, poaching or other mass mortality have not driven this shift. Although it may be partially attributed to a slow social readjustment to a safe environment after protection from hunting and poaching in the late 1970s, Fishlock suspects that matriarchs hold the key. As the Amboseli population has thrived, matriarchs have become older, and families larger under their leadership. A family’s propensity to spend time with other families within the network has declined. From Fishlock’s network analyses of the Amboseli elephants, it looks like matriarchs become less gregarious and more conservative in their old age.
“It looks like matriarchs become less gregarious and more conservative in their old age”
When it comes to survival, however, having a wise old matriarch to lead you is just as important as having other elephants to learn from in a wide social network. And the two influences are intertwined because that matriarch determines who is in your network to learn from. “Good matriarch decisions balance the needs of the group, avoiding unnecessary travel while remembering when and where good resources are available,” says Fishlock. Studies in Amboseli have revealed that families with older, larger matriarchs range over larger areas during droughts, apparently because these females better remember the location of rare food and water resources. “The matriarch has a very strong influence on what everybody does,” she says, though exactly how they communicate their will to the group remains a mystery.
The idea that groups led by older matriarchs might have a survival advantage gains support from a study of elephants in Tangarire National Park in Tanzania. In 1993, infant elephant death rates rose from an annual average of just 2 per cent to around 20 per cent during a nine month period of drought. With their dry-season refuge parched, some family groups stayed in the park, while others made off for places unknown. Young mothers were far more likely to stay put and to lose calves than older ones, and families that migrated out of the park had lower mortality than those that remained. Since matriarchs lead long-distance group movements, it suggests that older females, with their specialised knowledge of where to go to find enough food and water, provide a survival advantage for their extended family, explains Charles Foley of the Wildlife Conservation Society, who co-published the findings in 2008 ().
More recent and direct evidence of the benefits of wise old matriarchs has come from Karen McComb at the University of Sussex in the UK. Using recordings of lions roaring, she tested the responses of Amboseli matriarchs of different ages in the social context of their family group. Elephants encounter lions infrequently, but they are one of the few predators that pose a real threat, especially for young calves. That threat is enhanced if the lion is male, as males, unlike females, are capable of overpowering a young elephant even when hunting alone. McComb found that older elephants – aged 60 and over – seemed to listen longer to male than female roars, and their group huddled together more frequently and closely than did those of younger matriarchs. It suggests , and that matriarchs call the shots when it comes to deciding what anti-predator strategy to adopt, she says.
Older matriarchs also seem to be better at judging “stranger danger” from other elephants. At Amboseli, each family group encounters some 25 other families in the course of the year, representing about 175 other adult females. Encounters with less familiar groups can be antagonistic and if a family anticipates possible harassment it assumes a defensive formation called bunching. McComb tested whether a matriarch’s age influenced her ability to discriminate between contact calls. that families led by older matriarchs were less reactive overall, but bunched more in response to the sound of less familiar individuals than did families led by younger females. They suspect this is because older matriarchs have a larger memory catalogue for elephant voices, allowing them to more precisely distinguish between familiar and unfamiliar ones, and respond appropriately.
There may be more to good leadership than just the wisdom that comes with age, though. Elephants appear to have personalities and Lee and Moss wonder whether certain character traits might be associated with effective leadership. They have identified 26 traits possessed by elephants – things like confidence, fearfulness, opportunism and aggression – which group into four main personality dimensions: playfulness, gentleness, constancy and leadership. So far they have analysed just 11 adult females from one Amboseli family, and the matriarch does score highly in the leadership dimension. That may be expected. But by assessing more elephant families, the researchers hope to identify the traits shared by the most and least successful matriarchs, which in turn could help them pinpoint families best able to cope when the going gets tough.
If effective leadership is important in Amboseli, it is even more crucial in parts of Africa where threats are greater. During the 1980s, poaching halved Africa’s elephant population. Things improved after activists and researchers including Iain Douglas-Hamilton, founder of Save the Elephants, alerted the world and helped bring about an international trade ban on ivory in 1989. Relief came earlier in Kenya, where all trophy hunting, not just for elephants, was banned in 1978. However, in recent years poaching has been on the increase again as growing wealth in the Far East fuels demand for illegally procured ivory. The oldest animals with the largest tusks are prime targets (see diagram).
An inkling of the potentially dire consequences of killing matriarchs for ivory comes from Mikumi National Park in Tanzania, where elephants were heavily poached before 1989. The effects are still measurable. In 2008, a team led by Kathleen Gobush, now at Save The Elephants, reported that elephant groups hardest hit by poaching had younger matriarchs, weaker social bonds and lower relatedness. Analysis of their faeces revealed high levels of glucocorticoids, indicating chronic stress. And compared with groups with intact social structures, only half as many females had infants under 2. The stress of family disruption had clearly reduced their reproductive success ().
Losing a leader
In northern Kenya’s Samburu and Buffalo Springs National Reserves, where Eleanor lived, there are more signs that poaching is disrupting elephant family life. A team led by in Fort Collins, superimposed the genetic relationships of elephants there onto the social relationships they had observed over five years. They found that in this disrupted elephant society, . One of Wittemyer’s graduate students is now focusing on elephants orphaned by poaching, looking at the physiological stress and behavioural changes that result from losing their families, and what these animals do to rebuild their lives and societies.
We do not yet know the full extent of the damage caused by the killing of wise old matriarchs. Given that they are instrumental in solving the everyday problems of keeping their groups fed, watered, safe and reproducing, their entire social network will feel the loss. But work by Wittemyer and Douglas-Hamilton on heavily poached elephant populations suggests that despite disruptions to social structure, over the long term, the elephants and their networks are resilient. They can and will recover if poaching pressure can be lifted, but that is a big “if”.
Matriarchs may be adept at solving the problems faced by the elephants that look to them for leadership, but at the moment humans are their greatest problem, one that they cannot resolve for themselves.
This article appeared in print under the headline “Pachyderm politics”
