The series of organisms eating one and being eaten by other is called food chain. A simple food chain consists of producers, herbivores and carnivores. The length of food chain is generally limited to 3-4 trophic levels due to energy loss. In grazing food chain the producers (ie, plants) are eaten by herbivores (ie, rabbit, deer, cow etc) and the herbivores are eaten by carnivores. Therefore, the removal of most of the carnivores resulted in an increased population of deers.