While we know that all elephants are herbivores, the specifics of their dietary preferences have always remained a mystery. Now, in a study published in the journal Royal Society Open Science, an international team of researchers employed innovative techniques to unravel the dietary habits of two elephant groups in Kenya. Their findings not only shed light on the individual eating habits of the creatures but also contribute to conservation strategies aimed at ensuring their well-being and sustained growth.
Lead study author Tyler Kartzinel, an assistant professor at Brown University, emphasized the importance of understanding the dietary needs of animals for successful conservation efforts.
The study tells us about the variety of food species individual elephants eat over a day, a season, and more extended periods,” Kartzinel told ZME Science. “We already knew elephants eat an incredible diversity of plants to support their bulk, but we didn’t know how often members of a group that forage together make different selections from the same available options.”
“We also already knew that elephants have foraging strategies that can be sensitive to the seasons, often switching from eating fresh grasses after it rains to trees when it’s dry, but it was often challenging to accurately identify which species or variety of species they were selecting from each of those very broad categories of plants. The major advance is the opportunity to understand not just what elephants are doing in aggregate as a population, but how much each animal acts individualistically versus in concert with its group.”
Barcoding for DNA
The researchers utilized a cutting-edge genetic technique called DNA metabarcoding, a tool developed to analyze the DNA fragments of plant material eaten by studying fecal samples. By matching these fragments to a library of plant DNA barcodes, they could identify the specific types of plants consumed by each elephant. This study marks the first successful application of DNA metabarcoding to address long-standing questions about the social foraging ecology of animals.
“There are many useful and complementary approaches for analyzing animal diets, but dietary DNA metabarcoding is becoming the gold standard method for identifying foods from animal diets because it enables us to characterize the diets of many animals efficiently, precisely, and accurately,” Kartzinel said.
The team compared the new genetic technique with stable isotope analysis, a method involving the chemical analysis of animal hair. While stable isotope analysis had previously revealed broad dietary patterns, it could not discern the specific plants in the elephants’ diets.
By combining DNA metabarcoding with stable isotope analysis, GPS tracking and remote-sensing data, the researchers examined dietary variations among individual elephants within two groups. Surprisingly, they discovered that the dietary differences among individuals were often far greater than previously assumed, even among closely related family members.
The study’s findings shed light on how social bonds keep elephant family groups together in a world of limited resources. Although elephants share the same environment and seemingly eat the same plants, their preferences and physiological needs cause them to vary their diets. This variety ensures enough plants to go around, preventing competition among the group.
The implications of this study extend beyond the realm of ecological curiosity. Conservation biologists can leverage these insights to create environments that support successful reproduction and population growth for elephants and other wildlife species. Providing a diverse range of plant resources not only meets the dietary requirements of these animals but also reduces the likelihood of inter-species competition and the consumption of human food sources, such as crops.
“People are often surprised by how hard it can be to accurately characterize animal diets, which is why we can still learn so much about the lives of such well-loved species as elephants,” Kartzinel said.
“When the method is combined with complementary data on what animals are doing in their environment, better knowledge of how they get their nutrition could revolutionize our ability to understand and conserve the species we care so much about.”
