Grasses make up most of an elephant’s daily diet.  This means that elephants travel on most days to find clearings at the edge of forests where they spend hours gathering grasses with their trunks.  After ripping off a bunch of stems, they typically swirl it in the air and pound it on the ground before putting into their mouths.  Presumably this rids the plant material of unwanted dirt and debris. 

photo M. Noonan

Most elephants repeatedly swirl and pound each bunch of grass before eating it

Like most herbivores, elephants depend on beneficial bacteria that produce necessary enzymes inside their digestive systems—enzymes that are able to break down the cellulose in plant cells and convert it to a source of energy for the elephants.  In other words, when an elephant eats grass it is really feeding the bacteria in its digestive system, and these bacteria in turn feed the elephant. 

Micrograph of elephant fecal matter showing numerous beneficial bacteria

However, elephants cannot maintain good health on grass alone.  Like humans, they need a minimal level of protein in their diet, and grasses are a poor source of protein.  This means that an elephant must also spend part of each day in search of plants that are in their active growing stages, plants that are producing new leaf buds and growing stems that have high levels of protein.  Additionally, they must find plants that will provide them with a minimum level of other necessary nutrients (calcium, magnesium and so on) that are essential to their health. 

photo M. Noonan

Elephants move daily into, and out of, grasslands

To satisfy all of its needs, an adult elephant consumes about 300 pounds of plant material per day, and it moves about 10 miles per day, seeking out and eating small amounts of many different plant species.  Naturalists have counted 112 different plant species that elephants consume at one time or the other throughout the year. 

It is not necessary to infer that elephants understand their nutritional needs in any conscious way.  It is just that they have been built with a taste for certain plant species, and that is enough to drive them to seek out and gather in the appropriate foods.   

Elephants live very long lives and they appear to remember locations of desirable plant species from year to year, and maybe even from decade to decade.  By leading the group from place to place, matriarchs evidently pass this knowledge down to their daughters and grand daughters.