Great survivors: Elephants of the Namib
DESERT elephants are approximately the same body size as savannah elephants, although their bodies may appear less bulky, probably from a lower food intake. Their feet appear to be wider, probably as a result of walking long distances on sand, which causes the footpads to be splayed out.
A full-grown male (bull) elephant can weigh up to 6 tons and be 4m high at the shoulder. Females are usually a little more than half that weight.
Elephants are known to live 60+ years in captivity, but most probably have shorter lives in the wild. We do not know the exact ages of the oldest elephants in the desert population, but estimate that some may be 40-50 years old. That means that the older elephants in the population are survivors of poaching during the War of Independence and Angolan War.
Teeth and tusks
Elephants have only four teeth, one on each side of the upper and lower jaw. They grow six sets of new teeth throughout their lifetime, and may die of starvation in old age when they can no longer chew.
Tusks are specialised teeth that continue to grow throughout an elephant’s lifetime. Tusklessness is an inherited trait that tends to run in family groups. The tuskless trait is found in some desert females, never in males, however both males and females are prone to tusk breakage, which may make them appear tuskless for a time, until the tusk grows out again.
Food and water
Elephants prefer to drink daily, but can go up to three days without water if necessary. Bulls will drink up to 160 liters per day. We have discovered that elephants dig wells in sandy river beds to purify their drinking water. Water, dust, and especially mud are sought out for bathing and coating the skin against sun and biting insects. Elephants eat almost any vegetation, including grasses, herbs, shrubs, leaves, bark, seeds, and fruit. Adult bulls can consume 250kg daily, although females eat less than that. During the wet season they prefer green grasses, shoots and buds, but in the dry season desert elephants have to rely on woody vegetation, primarily camelthorn, mopane, and Ana trees and seedpods.
Elephants communicate with each other using scent, touch, and a variety of sounds, including low frequency rumbles and infrasound (which at <40Hz is below the level of human hearing) that can travel 5-10km or more.
Sociality and Reproduction
An older female (cow) leads the family and is called the matriarch. Family groups are usually related, and include the matriarch, her sisters, daughters, and their young. Related family groups are called “bond groups” or “kin groups,” and groups that share the same seasonal habitat are known as clans. Being the oldest, the matriarch has the longest memory and knowledge of water sources, seasonal foods, and migration routes to help her family survive.
Male offspring leave the family group at puberty, usually around 12-14 years old, and often form loose bachelor herds. The young males may attach themselves to older dominant bulls that act as “mentors,” guiding the younger ones.
Males undergo periods of heightened sexual condition called musth, when they become restless and more aggressive in their pursuit of estrous females. At his point bulls may clash and even fight, but will resume more tolerant relations once the musth period is over.
Females usually produce their first offspring around 10-12 years of age, after a 22-month gestation period. Calves depend on their mother’s milk until the age of two, but most will suckle until the birth of the next calf, usually at 3-4 years. In the desert population calves as old as six have seen still suckling.
Family groups of desert-dwelling elephants are smaller than those found in the savannah. In Etosha, for example, one may see 20-30 elephants in a family group. Family groups are generally all related females (grandmothers, mothers, daughters, sisters, aunts) and their juvenile offspring. In the desert, elephant family groups are quite a bit smaller, often consisting of a single adult female and her calves, or two adult sisters with their dependent offspring.
Adult bull elephants in the northern Kunene roam over very large distances. One collared bull covered an area from Skeleton Coast Park in the west to Etosha National Park in the east over the course of a few months.
Female desert elephants on the other hand, have smaller and somewhat more predictable movement patterns, tending to stay in or near the ephemeral rivers where water and forage are more readily available. Unfortunately, it was documented that two elephant family groups had abandoned migration due to the premature and tramatic loss of their matriarchs.
The desert elephants also make excursions into the low mountains, following traditional paths that are quite narrow and precipitous. They go in search of Commiphora, small bushes that are fragrant with resin, and known more commonly as myrrh. Elephants will go to great lengths to locate, uproot and eat entire plants, presumably because of the sweet taste, or possibly for medicinal purposes.