TWO SPECIES
Consider the moose and wolves living together on Isle Royale, a secluded island preserved as a national park. Without the influence of the wolves, what factors affect the population of moose? As predators, how do the wolves influence the number of moose that can survive? In years when fewer wolves are present, what happens to the population level of their prey, the moose?

Changes in each mammal's population have been carefully studied by scientists over a span of many years. After the data are collected, animal population levels are measured by calculating the natality rate (number of births) minus the mortality rate (number of deaths).