Let's take a look at elephants. Elephants are well known for their destructive foraging behavior, which is the main cause of the human-elephant conflict in Asia and Africa, but this behavior surprisingly provides a plethora of services to animals of a more modest size within the ecosystem. Elephant feet create indents in the ground which may fill up with water brought to the surface from underground. These small puddles open up drinking opportunities for small animals like frogs and rodents who uses the elephants' weight as a service to themselves (although many of their friends may have been flattened in the process).
Next, as elephants strip trees of all their nutritious growths, leaving them either damaged or dead, and even bulldoze some with their hefty maneuvering in search of food, the resulting damaged or dead trees may provide nests for certain tree dwelling animals; a study showed that arboreal lizards in Kenya are positively affected by an increase in elephant-damaged trees in an area as they make use of the refuges indirectly engineered by the elephants.
Another study showed that small bird species, like the southern ground hornbill, can be positively influenced by elephants' destructive behavior via the creation of nesting sites. Yet another study suggested that vervet monkeys, which feed off the gum produced by certain tree species like acacia (important components of an elephants' diet), may benefit from elephants' bark stripping and branch breaking feeding behavior because of the plentiful helpings of gum produced by these processes. Elephants however are clearly unaware of their important role as an ecosystem engineer.
(Photo: Shankar S.)