PREDATOR PREY POPULATIONS.
Predators influence the death rate, birth rate and survival rate of their prey. they influence the death rate by killing adults, the birth rate by eating eggs and hatchlings and survival rate by killing the juveniles. in nature, predators rarely completely eliminate their prey. if all prey die, the predator population us under threat of starvation. most predators miss more prey than they catch.
if the population sizes of the predator are plot don't eh same graph as the prey, it can be seen that the total number of prey is greater than the total number of predators. and the predator cycle follows the prey cycle (predator-prey cycles). as numbers of prey increase, there is more food for the predator so the numbers of predator is increase. more predators means less prey can survive and so the number of prey begin to decrease. now there is less food so the number of predators decreases, which means more prey will survive and prey number numbers increase. thus the cycle continues.
when ecologists interpret predator-prey cycles, they must also consider other variables such as migration, climate changes and other species.