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A rare species
is a group of organisms that are very uncommon or scarce. This designation may be applied to either a plant or animal taxon, and may be distinct from the term "endangered
An endangered species is a population of organisms which is at risk of becoming extinct because it is either few in numbers, or threatened by changing environmental or predation parameters...
" or "threatened species
Threatened species are any speciesg animals, plants, fungi, etc.) which are vulnerable to endangerment in the near future.The World Conservation Union is the foremost authority on threatened species, and treats threatened species not as a single category, but as a group of three categories,...
" but not "extinct".
Designation of a rare species may be made by an official body such as a national government, state or province. However, the term is used more commonly without reference to a specific criteria. The IUCN does not normally make such designations but may use the term in its scientific discussions.
The concept of rarity is established from having a very small number of organisms worldwide, usually a number less than 10,000; however, the concept is also influenced by having a very narrow endemic
Endemism is the ecological state of being unique to a defined geographic location, such as an island, nation or other defined zone, or habitat type; organisms that are indigenous to a place are not endemic to it if they are also found elsewhere. For example, all species of lemur are endemic to the...
range and/or fragmented habitat
Habitat fragmentation as the name implies, describes the emergence of discontinuities in an organism's preferred environment , causing population fragmentation...
A species may be endangered or vulnerable, but not considered rare if, for example, it has a large, dispersed population but its numbers are declining rapidly or predicted to do so. Rare species are generally considered threatened simply because the inability of small population size
Small populations behave differently from larger populations. They often result in population bottlenecks, which have harmful consequences for the survival of that population.-Demographic effects:...
s to recover from stochastic events, and the potential for a rapid decline in population.
- Biodiversity Action Plan
A Biodiversity Action Plan is an internationally recognized program addressing threatened species and habitats and is designed to protect and restore biological systems. The original impetus for these plans derives from the 1992 Convention on Biological Diversity...
- Critical depensation
In population dynamics, depensation is the effect on a population whereby, due to certain causes, a decrease in the breeding population leads to reduced survival and production of eggs or offspring...
- Endangered Species Recovery Plan
- Common species
-Definitions:Common species and uncommon species are designations used in ecology to describe the population status of a species. Commonness is closely related to abundance. Abundance refers to the frequency with which a species is found in controlled samples; in contrast, species are defined as...
- Abundance (ecology)
Abundance is an ecological concept referring to the relative representation of a species in a particular ecosystem. It is usually measured as the large number of individuals found per sample...