Limiting Factors

Limiting factors are things that prevent a population from growing any larger. For example, 10 rabbits may live in a habitat that has enough water, cover and space to support 20 rabbits, but if there is only enough food for ten rabbits, the population will not grow any larger. In this example, food is the limiting factor.

Food is not the only factor that may limit population growth. For example, there may be enough food to support a thousand birds in a certain area, but only suitable nesting sites for one hundred. Or perhaps there is plenty of food, water, cover and space to support a larger population of pheasants in an area, but predators are the limiting factor.

Limiting factors are very closely tied to carrying capacity. Many kinds of animals can increase in numbers very quickly, and may temporarily exceed the carrying capacity of their habitat. This results in stress, starvation, disease, predation and parasites, poor reproductive success and damage to the habitat. For example, multiplying muskrats can very quickly eat all the vegetation in a marsh. With the vegetation gone, food becomes the limiting factor and the muskrats may starve or move to another area. The marsh now has a reduced carrying capacity for muskrats until the vegetation grows back again.