Researchers say the diet and behavior of elephants, evidenced by the chemical makeup of their tail hairs, shows how they compete with other species, BBC News reported.
The data, published in Proceedings of the National Academy of Sciences, comes from a six-year study following a single family of elephants in northern Kenya.
It shows how the elephants lost out to cattle grazing on grasses and that the rate of conception is rising as food and water resources become more abundant each year.
Researchers are tracking the elephant family using GPS receivers on each individual and determining a dietary history from the hair on their tails.
The hair shows their chronological history in an “isotope record”. Isotopes are naturally occurring variations of atoms that are chemically identical but have a slightly different mass.
The elephants carry different food or water sources that might contain different ratios of isotopes of carbon, hydrogen or nitrogen.
The power of the maxim “you are what you eat” is evident in a clear record of the elephants’ diets that are found in the proteins that made up their tail hairs.
Thure Cerling, the University of Utah professor who lead the research, said they now have a long-term record that allows them to see what one normal family is doing over a long period of time.
Researchers have also analyzed the content of deuterium – an isotope of hydrogen – in the elephants’ tails to determine the pack’s water sources.
Professor Cerling told BBC News that during the dry season, the river they’re accessing comes from far away, so the water has had a lot of time to evaporate and change its isotope composition.
“Then during the rainy season, the rivers come up and the whole isotope composition changes and we’re able to actually see that,” he added.
However, the team was surprised to find that one season, the elephants apparently did not eat grasses that should have been readily available.
Cerling said when the rainy season comes you get this big sprouting of grasses, but they can’t access it until it is 30 to 50 centimeters high.
“It’s got to grow tall enough before they can actually yank it off with their trunks,” he said.
“We have this one incident where they apparently missed an entire good season of grass resource; the GPS data shows that they were outside [Samburu National Reserve] in a community area where it appears that they had to compete with cattle. They got out-competed in that situation,” he added.
Conceptions were also found to have risen sharply just a few weeks after the rainy season brought abundance of food and water.
Cerling explained that the elephants bulk up during the rainy season and get into good condition right as things are starting to get good.
The research shows that the elephants’ 22-month gestation period means that the maximum birthing period is shortly before things get good again””when they have adequate water and the right time to access the high-protein grass sources.
Elephant experts believe the new approach gives an intimate look into the elephants’ behavior and diet in a way that traditionally could not be done.
Cerling said the recent findings point to an imminent problem of broader interest, adding that it brings to light the worry about the conflict of how humans want to use resources and how wildlife wants to use resources.
He said global climate change is going to change the available resources and as populations increase dramatically, like in Africa, it will lead to more competition for the resources.
“If you’re concerned about preservation of wildlife then you have to worry about that competition,” he warned.
However, he said the method could be extended “to other regions throughout Africa”.
“The rest of Africa also is changing land use, and in all parts of Africa where elephants and humans coexist, there is resource competition.”
The team hopes to keep monitoring the elephants, including other families, for another 10 to 15 years, which will allow them to “look at how climate and land use change affect the elephants.”
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Image 1: A female African elephant walks in Kenya’s Samburu National Reserve. Note the hairs on her tail. Scientists from the University of Utah and Save the Elephants analyzed chemical isotopes in elephant tail hairs to study what one family of elephants ate and where during a six-year period. Their findings reveal that when elephants sometimes wander off their reserves during the rainy season, cattle out-compete them for grass, showing how human encroachment further threatens the endangered pachyderms. Credit: Thure Cerling, University of Utah
Image 2: An extended family of elephants walks from Kenya’s Samburu National Reserve and across the Ewaso N’giro River into the Buffalo Springs National Reserve. Researchers from the University of Utah and Save the Elephants placed tracking collars on members of an elephant family named “the Royals” and studied chemical isotopes in their tail hair to develop a six-year record of the elephants’ movements and diet. The method is expected to help scientists understand how climate change and human encroachment will further threaten the endangered animals. Credit: Mahala Kephart, University of Utah
Image 3: A female African elephant is followed by some young adults (left) in Kenya’s Samburu National Reserve as other family members walk nearby (right). A six-year study by researchers from the University of Utah and Save the Elephants showed how tracking collars and analysis of chemical isotopes in elephants’ tail hairs can allow detailed monitoring of their movements and diet — useful information for conservationists working to protect the endangered animals from global warming and human encroachment. Credit: Thure Cerling, University of Utah
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