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The oldest elephants that roam Mozambique’s Gorongosa National Park bear indelible traces of the country’s 15-year civil war: most of them have no tusks. They are the only survivors of the conflict, during which around 90% of these endangered animals were killed to feed the combatants, but also to buy weapons, thanks to the sale of ivory.
In Gorongosa, having no tusks turned out to be a biological advantage over poachers. According to the latest figures, a third of young females, those born after the end of the war in 1992, never had tusks. Normally, this characteristic affects only 2-4% of female African elephants.
Decades ago, around 4,000 pachyderms lived in Gorongosa according to Joyce Poole, an elephant behavior specialist and National Geographic explorer who studies these animals in the park. But after the civil war, they numbered only in the hundreds. In her new study, which has not yet been published, the scientist reveals that of the 200 known adult females of the park, 51% of those who survived the war, aged 25 years or more, were devoid of tusks, just like 32% of females born after the war.
Joyce Poole, also scientific director of the nonprofit Elephant Voices, says that at a comparable age, a male elephant’s tusks are larger and heavier than those of a female.
“But when a strong poaching pressure has been exerted on a population, poachers also begin to take an interest in older females,” she explains. “Over time, in the older population, you start to see this significant proportion of defenseless females.”
Mozambique’s elephants are not the only ones affected by this tuskless trend. Similar changes have been observed in surviving female elephants and their calves in countries with a history of heavy poaching. In South Africa, the practice has had particularly extreme repercussions: in the early 2000s, 98% of 174 female elephants in Addo Elephant National Park had no tusks.
“The frequency of the absence of tusks among elephants in Addo is truly remarkable. It shows that the significant pressure exerted by poaching has not only resulted in a decrease in the number of elephants in a population,” says Ryan Long, ecoethologist at the University of Idaho and National Geographic explorer.
The “consequences of such drastic changes in elephant populations are only beginning to be studied.”
In areas where poaching is high, such as southern Kenya, the size of tusks has also decreased. In a study published in 2015, Duke University and the Kenya Wildlife Service compared the size of the tusks of elephants captured in the region between 2005 and 2013 with those of pachyderms slaughtered between 1966 and 1968, that is, before the important episode poaching that took place in the late 1970s and early 1980s.
Significant differences in size were then observed. The elephants that had survived this period of intense poaching had much smaller tusks: they were about 20% smaller in males, compared to over 33% in females.
The same phenomenon was observed in their offspring. On average, the tusks of male elephants born after 1995 were 21% and 27% smaller, respectively, than those of males and females in the 1960s. size of tusks are indirect”, studies on mice, baboons and humans have shown that the size of incisors, the equivalent of tusks in elephants, is hereditary and has a “consistent genetic influence.”
What Are the Consequences for Elephants?
Indeed, if the tusks are nothing but teeth that have grown too much, pachyderms use them on a daily basis for various purposes, such as digging holes in order to find water or minerals that are essential to them, and removing the bark from the trees to meet their fiber needs. Males also need it to compete in the breeding season.
The work elephants do with their tusks is also vital to other animals. “As a keystone species, elephants are important to various lower species that depend on them to knock down trees and dig holes for access to water,” says Ryan Long. Pachyderms also use their tusks to indirectly create habitats: for example, some lizards like to settle in trees battered or knocked down by grazing elephants.
If elephants no longer live in one place, move at the same speed, or travel to the same places, the ecosystems around them could be affected. “Any or all of these behavioral changes could alter the distribution of elephants, and it is these large-scale changes that are most likely to have consequences for the rest of the ecosystem,” adds Ryan Long.
The latter, along with a team of ecologists and geneticists, begins to study how defenseless elephants lead their lives. Last June, they started following six adult females in Gorongosa Park, three of them without tusks, belonging to three different herds. Scientists took blood and dung samples and fitted the pachyderms with GPS collars, in order to track them for a few years, or until each device’s battery stopped working. Samples of excrement will also be collected periodically to analyze the diet of the elephants.
The objective of this study is to obtain more information on the movements of animals, on the way they eat and on their genomes. Ryan Long hopes to detail how these elephants who cannot use their tusks as a tool have changed their behavior to get the nutrients they need.
Rob Pringle, a researcher at Princeton University, meanwhile, plans to analyze their droppings to learn more about the diet and the army of microbes and parasites that live in each elephant’s intestines. Shane Campbell-Staton is also participating in the study: this evolutionary biologist from the University of California will analyze blood samples to try to find how genetics play a role in the absence of defenses.
How precisely this characteristic is transmitted is a “mystery,” says Shane Campbell-Staton. In females, the absence of tusks seems to be disproportionately provided. The scientist indicates that in males, this characteristic would logically prevent them from competing with others in order to mate with females. However, if the lack of defenses is transmitted through the X chromosome, which helps determine sex and carries genes for different hereditary characteristics, many males should be defenseless as it is always their mother who Gives them the X chromosome.
“But I don’t see that. Males without tusks are extremely rare in African elephants,” says Shane Campbell-Staton.
An observation that Joyce Poole confirms: during her career, she saw only three or four defenseless males and none of them lived in Gorongosa.
Although the behavior and diet of elephants without tusks have not been officially compared to those of elephants that do, Josephine Smit says that during her research, she observed elephants without tusks that found how circumvent the problem posed by the absence of these long incisors.
“I have seen elephants without tusks feed on bark, which they pulled out with their trunks or sometimes with their teeth. The scientist does not exclude that they benefit from the involuntary help of other elephants. They may also turn to tree species whose bark is easier to remove or which has already been partially removed by other elephants, which makes it easier for them to tear off the bark.
The recent ivory trade ban in China and the United States could help reduce demand. However, the time it takes for a population with a large proportion of defenseless elephants to increase again varies, as does the time it takes for pachyderms to regain their tusks. Thus, if many Asian elephants do not have tusks, it is undoubtedly due to poaching, long practiced in the region, and the fact that the elephants which were endowed with them were captured for work.
“In Asian elephants, females have no tusks. In males, depending on the population and the country where they live, they also often lack these long incisors,” explains Joyce Poole. However, the reasons why the lack of tusks between Asian and African elephants vary so widely are unknown.
Joyce Poole and other scientists point out, however, that in parts of Asia traditionally targeted by ivory poaching, the number of defenseless elephants is high, as is Africa. A finding which shows that Man leaves a lasting mark on the largest land mammal.