extirpation

Extirpation, in ecology and conservation biology, refers to the local disappearance of a species from a defined geographic area, while the species continues to exist elsewhere. It is also called local extinction. Extirpation differs from extinction, which is the permanent disappearance of a species from all parts of its range.

Causes include habitat destruction or alteration, overutilization, invasive species, disease, and climate change, often in combination. Local populations may decline due to fragmentation, reduced gene flow, or stochastic events, leading to zero individuals in a region. Because it is scale-dependent, a species can be extirpated from a watershed, a country, or a biogeographic region but persist elsewhere.

Examples illustrate its geographic nature. The gray wolf was extirpated from much of the eastern United States in the 19th and early 20th centuries; in other regions, local extirpations have affected freshwater fishes, amphibians, and plants due to damming, pollution, or land-use change. The European bison was driven to near extinction in the wild and survived only in captivity before reintroduction in parts of Europe. Some species have recovered in parts of their range after protection and habitat restoration, while remaining extirpated in others.

Conservation implications focus on preventing extirpation by protecting habitat, maintaining connectivity, regulating harvest, and controlling invasive species. When feasible, reintroduction and habitat restoration can restore a species to parts of its former range, though success depends on source populations and ecosystem conditions. Monitoring helps identify at-risk areas and guides management decisions.