Carrying Capacity - Examples

Examples

One of the world's best-studied predator–prey relationships is the moose and wolf population of Isle Royale National Park in Lake Superior. Without the wolves, the moose would overgraze the island's vegetation. Without the moose, the wolves would die. The first scientists who studied the issue thought that the wolves would eventually overpopulate and kill all the moose calves, then die from famine. This has not occurred as inbreeding, disease and environmental factors have limited the wolf population naturally.

Easter Island has been cited as an example of a human population crash. When fewer than 100 humans first arrived, the island was covered with trees with a large variety of food types. In 1722, the island was visited by Jacob Roggeveen, who estimated a population of 2000 to 3000 inhabitants with very few trees, "a rich soil, good climate" and "all the county was under cultivation". Half a century later, it was described as "a poor land" and "largely uncultivated". The ecological collapse which followed has been variously attributed to overpopulation, slave traders, European diseases (including a smallpox epidemic which killed so many so quickly, the dead were left unburied and a tuberculosis epidemic wiped out a quarter of the population), social upheaval and invasive species (such as the Polynesian rats which may have wiped out the ground nesting birds and eaten the palm tree seeds). This combination of factors resulted in only 111 inhabitants living on the island in 1877.

The Chincoteague Pony Swim is a human-assisted example.

Both herds are managed differently. The National Park Service owns and manages the Maryland herd while the Chincoteague Volunteer Fire Company owns and manages the Virginia herd. The Virginia herd, referred to as the "Chincoteague" ponies, is allowed to graze on Chincoteague National Wildlife Refuge, through a special use permit issued by the U.S. Fish and Wildlife Service. The size of both herds is restricted to approximately 150 adult animals each in order to protect the other natural resources of the wildlife refuge.

A further example is the Island of Tarawa, where the finite amount of space is evident, especially since landfills cannot be dug to dispose of solid waste, due to constraints in the subsurface rock and lack of topographic elevations. With colonial influence and an abundance of food (relative to life before the year 1850), the population has expanded to the extent that overpopulation is transparently present.