Science magazine published a paper last week proposing an explanation for the high proportion of tuskless elephants in the Gorongosa National Park in Mozambique. Many major news organisations around the world reported on the paper and hailed it for its ground-breaking insights.
Researchers blame ivory poaching during the Mozambican civil war from 1977 to 1992 for the rapid increase in tusklessness in the Gorongosa herds. Armed forces on both sides of the conflict slaughtered elephant populations so they could sell the ivory to finance their war efforts. The carnage caused the local elephant population to decline by 90%.
As the elephant herds began to recover after the war, a relatively large proportion of females were born without tusks.
Tusklessness does occur naturally in female African elephants, even in the absence of poaching, but usually only in a small minority of elephants.
The proportion of tuskless elephants in Gorongosa, increased from under 19% in the 1970s to 51% thirty years later.
The paper argued that the dramatic increase in the proportion of tuskless elephants was an evolutionary adaptation because females without tusks were over five times more likely to survive the war than those with tusks.
The rapid change in the proportion of tuskless females is a direction function of the strength of selection. Tuskless elephants had a much higher chance of surviving the war and consequently a much higher probability for passing on their genes to the next generation even as the general population declined.
The researchers were curious as to why only female African elephants are born without tusks so they decided to examine their chromosomes. They took blood samples of 18 females with and without tusks and sequenced their genomes.
They found that tuskless females had a genetic variation in the region of the X-chromosome that plays a role in tusk development.
Females have two X chromosomes. If both are ‘normal’ the elephant has tusks. If only one chromosome is ‘normal’, and the other contains the variant, then she does not have tusks.
Males have only one X chromosome, and if it has the tuskless variant, the foetus dies.
To sum it up, ivory poaching gives an evolutionary advantage to elephants born without tusks. This results in a higher proportion of elephants being born without tusks in herds that have been butchered for their ivory.
Tusklessness in the Addo Elephant Park
The article published in Science magazine naturally made me think about the elephant herds in the Addo Elephant Park (AEP). There are currently over 600 elephants in the park and it is obvious even to the casual observer, that the majority of them do not have tusks.
I had always assumed the indiscriminate hunting in the late 19th and early 20th centuries had killed off the big tuskers. It is a part of the history of the AEP that I try not to think about too much, but the Science paper obliged me to do a little more research.
The rest of this Real Safari Newsletter summarises what I found out.
By the end of the 19th century most big game in what is today South Africa had been heavily reduced. Hunters had shot up wild animals for meat, ivory, skins and for fun for almost 200 years. The slaughter only intensified during the Anglo-Boer war (1899 – 1902).
In 1900, the Eastern Cape had the largest remaining population of elephants in South Africa – a situation that was not destined to last very long.
As it gradually dawned on the Cape government that its abundant wildlife would soon be no more, it banned the hunting of elephants with tusks weighing less than eleven pounds (Five kilograms). The Game Act of 1909 also prohibited the hunting of cow elephants.
The law was difficult to police, and exceptions were made when elephants damaged or destroyed farmers’ crops. They described the Addo elephants as ‘vicious’ thieves who raided crops and ‘hunted’ farmers. It was considered reasonable for a farmer to shoot an elephant that was ‘playing football with his pumpkins’.
The Cape Provincial Administration had difficulty balancing the demands of the farmers with early notions of wildlife protection. As a solution to this dilemma, it decided to setup a sanctuary for the elephants to protect the last remnants of the herds but hired a professional hunter to shoot out all the other elephants.
They chose Major Phillip Jacobus Pretorius to kill elephants outside the sanctuary and hoped to sell the ivory of the animals that he shot to offset the expenses of the exercise in 1919. It was a bad idea for many reasons, but arguably the most ironic was that the overwhelming majority of the remaining elephants had very little ivory to sell. Hunters had killed all the tuskers many years earlier.
Two centuries of carnage
We have to delve further back in history to find the reasons behind Pretorius’s disappointment. It is certain that the big tuskers were the first ones to be shot, but why were there so many adults that either had no tusks or very small ones?
The answer is that the slaughter of elephants for their ivory had begun almost 200 years before Pretorius fired his first bullets.
I came across several references to elephant hunting in the 1700s and many more in the century that followed.
It was reported as early as 1702 that a large party of European hunters had arrived in the Algoa Bay area in search of ivory. Throughout the next century hunting pressure on elephants intensified.
Thick bush in the region probably saved many elephants from the hunters’ bullets as reports referred to a herd of at least 300 near Alice in 1804 and ‘immense herds’ north east of Peddie in 1823. In the following year there were reports of ‘swarms’ of elephants near Grahamstown (where I currently live).
The large herds that roamed the Eastern Cape still carried substantial tusks and hunters were killing so many elephants that an ivory market was established at Fort Willshire, near Alice in 1824. Almost 23,000 kilogrammes of ivory were traded at that market within the first seven months of operations.
Similar markets were established in many other towns of the region.
It was the indiscriminate massacre of thousands of elephants for two centuries that led to the diminutive size of elephant tusks in the Eastern Cape when Pretorius went on his shooting spree.
Current population of elephants at Addo is burgeoning
The original proposal of the Cape Administration was to protect up to 70 elephants in the sanctuary which would be promoted as a natural habitat where residents of Port Elizabeth could come and see them.
Pretorius claimed however that after he had finished his contract to exterminate the Addo elephants, only 16 remained alive in the bush. When the sanctuary was finally established in 1931 five had already died.
In the early years, the fencing around the park was inadequate so its first warden, Harold Trollope, put out hay, pumpkins, pineapples and oranges in attempt to keep the elephants from straying onto farmlands.
The animals were encouraged to enter a cleared area where visitors could feed them oranges. It was part of the process of making the elephants more docile and accustomed to humans.
Visitors to the park were seen feeding oranges to resident elephants until sometime in the late 1970s. When the practice was eventually stopped, it was forbidden to bring any citrus fruit into the AEP for many years. It does not seem to be an issue any longer.
At the turn of the century, Addo boasted a healthy population of more than 300 elephants but there was still one small problem – most of the elephants did not have tusks, and those that did, were on the diminutive side. A genetic variant that favoured no tusks in females a hundred years ago, and the relatively young age of the Addo males, ensured that there were no impressive tuskers in the park.
In an attempt to rectify this genetic imbalance, SANParks arranged to bring in eight big bulls from the Kruger National Park in 2005. They all had impressive tusks and soon went about their business of impregnating as many cows as they could.
I was privileged to photograph Valli Moosa, one of these ‘Kruger Tuskers’, on several occasions before he was killed by a younger bull in December 2017.
Perhaps future generations will be able to see herds of big tuskers roaming around the park.
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References
Graham Kerley, Sharon Wilson and Ashley Massey (eds.) (2002) Elephant Conservation and Management in the Eastern Cape – Proceedings of a workshop held at the University of Port Elizabeth – 5 February 2002
Nicholas Jones (2020) Addo Elephant National Park 1900 – 1955: An Environmental History of the struggle between elephants and emerging commercial farmers in the Sundays River Valley. Masters of Arts thesis at the Nelson Mandela University.
Jules Skotnes-Brown (2021) Domestication, degeneration, and the establishment of the Addo Elephant National park in South Africa. Published in The Historical Journal, 64, 2 (2021) pp 357 - 383
Shane C. Campbell-Staton, Brian J. Arnold, Dominique Gonçalves, Petter Granli, Joyce Poole, Ryan A. Long and Robert M. Pringle (2021) Ivory poaching and the rapid evolution of tusklessness in African elephants. Published in Science 22 Oct 2021, Vol 374, Issue 6566, pp. 483-487 DOI: 10.1126/science.abe7389