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September 20, 2018

Impalas and seals conquer to get a partner

FAIR IN LOVE AND WAR: An elephant seal. Photo/STEVE KINUTHIA
FAIR IN LOVE AND WAR: An elephant seal. Photo/STEVE KINUTHIA

If you are reading this, it is very likely that you love nature and animals. It may also indicate that you are a fun of Natgeo wild and animal planet programmes when you have a chance to watch any of the two. If you have been watching any of the two channels that show the world of wild animals, you may have come across a large animal that is the size of a rhino but without a horn. It weighs about 4,000 kilos. It does not live in Africa. It lives in the American Pacific Ocean. They call it the elephant seal.

The seal is known to leave his home base in the southern oceans and travel a long distance under water. He drags his large flattened body ashore on an isolated island. Here, he finds a large number of female seals who, having given birth to their pups, are ready for mating again. In a confined area, the bull is at liberty to choose a fine harem of up to 40 or so sexual companions. He goes from one the next with complete abandon, mounting them at will –provided of course that he has established his credentials as the dominant male. Any female will submit to the crushing weight of a male three times her size, so long as he has worn his place fairly. She will protest noisily however, if a subordinate attempts to copulate with her.

Superficially, the male seems to be controlling this set up by virtue of his size and aggressively sending off his competitors. Yet within this polygynous mating system, the female too has a say in this matter. Not only does she make her displeasure known vocally, she also uses gestures should a less than dominant male try to mate with her. She also makes a lot of noise during copulation with a subordinate male to attract the attention of the boss to intervene.

Actually, female 'choice' appears to be more subtle than this. A female knows that before the male departs after the brief mating period, she must be inseminated. But as the season comes to an end, even the dominant male, worn down by constant fighting and jealously defending his harem, becomes an unreliable source of sperm. So the female will instinctively calculate that it is better to have loved and lost than to miss the show completely. If she had not had a chance at the dominant male, she will willingly allow the subs to mate and father her offspring.

The process by which a female in the wild tries her utmost – at least to ensure that most of her offspring are sired by the strongest fittest male – is observed all the time. During the mating season in East Africa, which actually comes anytime there is enough food, impalas compete ferociously for the attention of females and guardianship of their harems, which can sometimes number more than 70 females with their young and sub adults. Again, a mighty physique and the ability to use it to good advantage in a fight with competing males, is of prime importance.

So too, is the male impala’s capacity to communicate its potential supremacy with blood curdling calls. Part of the physiological preparations for the vigorous mating season, is a change in the male vocal apparatus. The voice box enlarges in order to produce the guttural roars that are heard from great distances. It is a two-edged signal – to keep males at bay and to remind females of their continued wisdom in their choice of a partner. Before the harem keeper is challenged physically by another male, he is first challenged vocally. If an intruder can outroar an incumbent, or equal him, then the situation is open for physical confrontation to decide the matter.

So, often enough is mate selection determined by the female choosing a physically strong male – one that will give her sons and daughters desirable bodily characteristics. Some psychologists have speculated as to whether something akin to this might be operating among humans. Their argument runs along these lines. At earlier period of human evolution, it was important for the male to be swift-footed, hard of muscles and with keen eye to be able to bring bacon home. Do we still retain albeit shadowed, the same primal instincts? Who chooses a mate – the female or the female? Are men polygamous or are the ladies the ones who practise polyandry? Food for thought.

Steve Kinuthia is a veteran professional safari guide and the proprietor of Bushman Adventures Limited.

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