Ecological release refers to a population increase or population explosion that occurs when a species is freed from limiting factors in its environment. Sometimes this may occur when a plant or animal species is introduced, for example, to an island or to a new territory or environment other than its native habitat. When this happens, the new arrivals may find themselves suddenly free from the competitors, diseases, or predatory species, etc. in their previous environment, allowing their population numbers to increase beyond their previous limitations. Another common example of ecological release can occur if a disease or a competitor or a keystone species, such as a top predator, is removed from a community or ecosystem. Classical examples of this latter dynamics include population explosions of sea urchins in California's offshore kelp beds, for example, when human hunters began to kill too many sea otters, and/or sudden population explosions of jackrabbits if hunters or ranchers kill too many coyotes.
The foreign species either flourishes into a local population or dies out. Not all released species will become invasive; most released species that don't immediately die out tend to find a small niche in the local ecosystem. Ecological release also occurs when a species expands its niche within its own habitat or into a new habitat.[1]