Elephants eat plants. That's common knowledge to biologists and animal-loving schoolchildren alike. Yet figuring out exactly what kind of plants they eat is more complicated. 

A new study from a global team that included Brown University conservation biologists used innovative methods to efficiently and precisely analyze the dietary habits of elephants in Kenya. Their findings on the habits of individual elephants help answer important questions about group food searching behaviors, and aid biologists in understanding the conservation approaches that best keep elephants not only sated (饱的) but satisfied. 

"When I talk to non-ecologists, they are surprised to learn that we have never really had a clear picture of what all of these large animals actually eat in nature, " Kartzinel, an expert botanist who has conducted field research in Kenya, said. "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. "

Then the team compared the diets of individual elephants through time. In their analysis, they showed that dietary differences among individuals were often far greater than what had been previously assumed, even among family members that ate together on a given day. 

This study helps address a classic paradox (悖论) in wildlife ecology. Kartzinel said: "How do social bonds hold family groups together in a world of limited resources?" In other words, given that elephants all seemingly eat the same plants, it's not obvious why competition for food doesn't push them apart and force them to search for food independently.

"The simple answer is that elephants vary their diets based not only on what's available but also their preferences and physiological needs, " said Kartzinel. These findings help inform theories of why a group of elephants may search for food together: The individual elephants don't always eat exactly the same plants at the same time, so there will usually be enough plants to go around.

These findings may offer valuable insights for conservation biologists. To protect elephants and create environments in which they can successfully grow their populations, they need a variety of plants to eat.