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A threatened species is any species (including animals, plants and fungi) which is vulnerable to extinction in the near future. Species that are threatened are sometimes characterised by the population dynamics measure of critical depensation, a mathematical measure of biomass related to population growth rate.
- Threatened Species Definition
- Threatened Species Overview
- Criteria For A Threatened Species
- Examples of Threatened Species
A threatened species is any species which is vulnerable, endangered, or critically endangered. The International Union for Conservation of Nature, or IUCN, is commonly referenced as a leading organization in determining if a species can be considered a threatened species or not.
The IUCN also defines the category nearly-threatened species, for any animals which are likely to become threatened species within the foreseeable future. The IUCN designation of threatened species can be seen below. Other organizations may define a threatened species slightly differently. For instance, the United States Endangered Species Act defi...
Population Size Decline
While the criteria for each organization differs, the following are general criteria developed by the IUCN and other organizations to determine if a species can be labeled a threatened species. One of the most important markers of a threatened species is the population size, and its overall direction. A small, decreasing population is much more likely to be threatened than a small, increasing population. Scientists typically measure a population using mark-recapturestudies. In these studies,...
Number of Mature Individuals
Along those lines, scientists must also measure and separate the number of sexually active adults in the population. A sea-turtle, for instance, can lay hundreds of eggs each season. It would be inaccurate, however, to consider all of those offspring as contributing to the next generation. The fact for sea-turtles and many other animals is that many offspring will not make it to sexual maturity.In calculating a threatened species, it is more important to focus on the individuals who have alre...
Geographic Range
Almost as important as the number of individuals is the geographic range of a threatened species. A species with a cosmopolitan distribution (found globally) is unlikely to be in danger of going extinct.However, if the reproducing adults in that range are actually separated and cannot reproduce, the possibility of extinction increases. This phenomenon is known as habitat fragmentation. It can be natural, such as an impassable mountain range, or man-made, like a highway. Either way, if a speci...
Black-footed Ferret
The black-footed ferret (Mustela nigripes) is a threatened species on the verge of extinction. While it is thought that the ferret once had an extended range, poisoning of their prey (prairie dogs) and a plague killed off their population. Further, as the plains became more populated, many prairie dog towns were destroyed, killing off their food source. By the 1960s, the black-footed ferret was extremely rare and limited to a few populations in Wyoming. By 1987, it was considered extinct in t...
Tawny Nurse Shark
Found off the coast of Australia and Indonesia, the tawny nurse shark (Nebrius ferrugineus) is a threatened species considered vulnerable by the IUCN. This threatened species has mostly declined, like many sharks, due to fishing practices and harvesting them for their fins. Gill nets and other forms of fishing which are non-selective often catch the sharks and kill them in the process. The sharks are also hunted for their fins, which are part of shark-fin soup, an Asian delicacy which is supp...
Other Species
These two species hardly represent all the species on the threatened species list. The IUCN keeps a global list, but every country and even locality may keep their own list or assessment protocol.Further, while these two were vertebrate species, vertebrates represent only a fraction of all threatened species. Below is a graph which breaks down the approximate proportions of species currently on the IUCN Red List. As you can see, amphibians and other vertebrates do make up a large portion of t...
- Gabe Buckley
Jan 23, 2019 · Learn the difference between the Red List and the Endangered Species Act, two common systems of classifying a species’ extinction risk. Find out how scientists assess the population size, range, and probability of extinction of threatened species.
- 91 min
An endangered species is a type of organism that is threatened by extinction. Species become endangered for two main reasons: loss of habitat and loss of genetic variation.
Established in 1964, The International Union for Conservation of Nature’s Red List of Threatened Species has evolved to become the world’s most comprehensive information source on the global conservation status of animal, fungi and plant species.
Mar 18, 2024 · Threatened species are plants and animals that are likely to become endangered within the foreseeable future throughout all or a significant portion of its range. How Does Extinction Happen? Species disappear because of changes to the earth that are caused either by nature or by the actions of people.
Threatened species definition: a plant or animal species generally perceived as likely, in the near future, to become endangered within all or much of its range. See examples of THREATENED SPECIES used in a sentence.
