Sexual segregation in Amboseli: male and females elephants do things differently
One of the most frequent comments I hear when talking to people about elephants is some variation of “that’s just like us!” To me, it isn’t really surprising; there are many similarities because elephants, like humans, are long-lived creatures that inhabit a social world with many levels of friends, enemies and competitors. The most recent occasion, however, made me laugh. During a lecture, I was explaining that male and female elephants could almost be separate species, they lead such different lives, and a rather taciturn-looking gentleman muttered the inevitable.
The reasons behind the segregation of the sexes really boil down to the constraints that reproduction places on females. Although small calves are expected to keep up with the family more or less from day one, they do slow the rate at which families can travel. Even more of a constraint is the need for females to drink every day, to assure their milk supply. Travelling long distances in areas where the water supply may be unpredictable is simply too risky for mothers with young calves.
Elephant mothers are fiercely protective of their calves, and when you consider that the average pregnancy last 22 months, that protectiveness should not come as a surprise. Beyond pregnancy, a calf is nutritionally dependent on its mother for most of the first 2 years of life, and will usually continue to suckle until the next calf is born, when they are around four years old. And this doesn’t even begin to cover the close mother-calf bond, as young elephants explore and learn their way around the social complexities of elephant life.
Although calves older than two can survive without their mothers, any calf orphaned before the age of nine is more likely to die than a non-orphan. Amazingly, the long-term research by ATE has shown that this risk persists for elephants well into their twenties. In addition, orphans can suffer the long term consequences of smaller body size: smaller elephants tend to reproduce later and, for females, tend to have smaller calves, which themselves have a reduced chance of survival. Each calf thus represents a precious investment by a female, well beyond the maintenance of a pregnancy.
A female’s life is entirely centred on her family. As a young adult, she helps look after the calves in the family (we call this behaviour “allomothering”), and then later on she rears her own calves, in the company of her grandmother, mother, sisters, aunts and female cousins. Females are almost never alone in Amboseli: if we spot a female on her own, we know she must either be ill, or in oestrus and has become separated from her family while being pursued by ardent males.
Families may break down into smaller units during the dry season, when food becomes scarce and individuals spread over a wider area in order to locate the most nutritious vegetation remaining. This is the advantage of elephants’ fission-fusion society, allowing members to go and fulfil their individual needs, if they want to do something different to the family activity. In Amboseli, the swamp vegetation provides a year-round source of food and as a result many of the elephant families remain closely associated.
With the use of infrasonic calls, elephants can keep track of friends and family members who may be many kilometres distant. In that sense, wild elephants are truly never alone, embedded in a world of sound (and eavesdropping!) that humans, with their paltry sense of hearing, probably find very difficult to imagine. When watching elephants, I often wonder how much I am missing through my primate’s reliance on vision. I sometimes think I would give a great deal to inhabit that world of sound, and of smell, for a while.
Anyway, that’s enough of my imagination; back to the elephants. What of “the boys”?
Males are totally socially independent once they leave their families during puberty, somewhere between the age of ten and twenty. The process of leaving is often driven by young males seeking out more exciting activities than family life offers them; mainly this is the chance to spend time with age-mates, or older males. With these partners they can joust and spar, testing their strength and finding their place in the hierarchy, or just “hang out”. There is nothing more guaranteed to make me smile than a group of young males striding across the Amboseli plain. My favourite time is when they’re posing to each other, imitating the impressive swagger of large musth males and occasionally breaking into a race.
Amboseli National Park contains the only permanent water in the Amboseli ecosystem, which is why females have to remain closer to the Park than the males do. Freed from the travel constraints that females experience, males range much further afield, especially during the wet season. It’s hard to put exact numbers on how far elephants move: much depends on the ecological conditions at the time and on the individual because some elephants are real “home bodies” and others are wanderers. Previous studies in the Amboseli ecosystem have shown that males occupy about 22% more space than females on average, and may cover up to 3,700 square kilometres in a year.
Males can go to feed in areas that are too far from water for females to travel to, and therefore access different types of vegetation to feed on. Because they range independently (although not necessarily alone) males do not have to mesh their travel needs with those of any companions; they can simply do their own thing. Males are also taller and heavier than females, and their feeding on trees can inflict more damage on plants, sometimes pushing them over. This makes them extremely important engineers for the vegetation dynamics of an area.
As young males venture further from the areas where they grew up, they may rely on spending time with other (often older) males, to help them learn about new areas to feed, rest, bathe and drink. They don’t have the needs of young calves to consider, and so they are free to take the risk to enter unfamiliar areas, where they may go a little thirsty before finding water. I’m always amazed by elephants in Angola, where the clearance of landmines made previously perilous areas accessible to elephants again. Males were the first to exploit the region.
If you are lucky enough to watch wild elephants (and if you have the means, this should be on your bucket list), you may come across a group of females with their calves (which may or may not be an elephant family), a solitary male, a group of males together, or a mixed group with both males and females present. Visitors to Amboseli National Park probably have a somewhat skewed view of what elephant daily life is like, because they see lots of elephants either travelling to the swamp, or already submerged in the lush green vegetation, and these groups tend to be large, and may easily merge with one another. (Of course this source of “bias” also affects our own elephant observations, and is something we have to bear in mind when doing our research, and particularly when interpreting our data.) It can seem as though elephants are (a) always in the Park and (b) always in, or close to, big groups.
Check out this video on the male musth cycle:
As always for elephants, the truth is a lot more variable, and therefore interesting. It’s only by knowing individuals over long periods that we are beginning to understand just how variable elephant life can be. Typically then, adult elephants spend time with their own sex, and not the other. Very few of the big adult males in Amboseli are seen in the Park, unless they are in the sexually active state of musth and seeking oestrus females. This is good news for the flow of genes between connected elephant populations, as males wander and mate with females from different areas. It does mean however, that if you study elephant families, as I do, you go for long periods without seeing the “big boys”, and it makes it that much more exciting when they turn up. Even for us humans!