Even though we could, most of us don’t want to eat the same food for every meal. Now researchers have discovered it's the same for African elephants, whose diverse and individualistic food selection shows they're incredibly discerning at the dinner table.
While the huge herbivores have a base diet of staples – also not unlike us – they eat a massive range of plant taxa, with one animal even showing to have more than 100 different species present in their poop sample.
A global team of scientists including Brown University conservation biologists has used DNA metabarcoding for the first time, to gain novel insights into the social foraging and food selection of two family groups of elephants in Kenya. Because elephants are so tricky to track for observation studies, little has been known about the social foraging aspects of the world’s largest terrestrial herbivore.
“When I talk to non-ecologists, they are stunned to learn that we have never really had a clear picture of what all of these charismatic large mammals actually eat in nature,” said study author Tyler Kartzinel, assistant professor of environmental studies and of ecology, evolution and organismal biology at Brown. “The reason is that these animals are difficult and dangerous to observe from up-close, they move long distances, they feed at night and in thick bush and a lot of the plants they feed on are quite small.”
DNA metabarcoding is a recent development in genetic detective work, in which a biological sample – in this case, elephant feces – has DNA fragments extracted from it and those are then matched to a database of plant DNA ‘barcodes.’
In addition to this, the team analyzed carbon stable isotopes from the feces and elephant hairs, used data from GPS tracking and remote sensing, and enlisted Paul Musili, director of the East Africa Herbarium at the National Museums of Kenya, to precisely identify the plant matter.
What they found was far greater diversity of diet, and differences among individual animals, which was a new insight into how elephants feed.
They eat a range of plant forms (herbs, trees, succulents) and plant parts (leaves, fruits, bark, twigs), but will also prioritize high-quality foods such as fruits and even feed from garbage dumps if the offerings there provide more bang for their nutritional buck than wild foraging.
The researchers also found there was selection based on physiological needs, such as pregnant or nursing elephants having a different diet to others, which may even suggest a type of ‘craving.’
This broad, sustainable diet is also crucial for survival in often resource-limited environments, with each adult elephant eating around 330 lb (150 kg) of plant matter per day.
“It’s really important for conservationists to keep in mind that when animals don’t get enough of the foods that they need, they may survive – but they may not prosper,” said Kartzinel. “By better understanding what each individual eats, we can better manage iconic species like elephants, rhinos and bison to ensure their populations can grow in sustainable ways.”
It’s hoped that such insights gained through new methods of genetic analysis can inform conservationists and land owners as to the kind of diversity needed for herbivorous species, and also how better to provide enrichment in captivity that offers quality as well as quantity.
"Each elephant needs variety, a little bit of spice – not literally in their food, but in their dietary habits," Kartzinel said.
The research was published in the journal Royal Society Open Science.
Source: Brown University
