critically endangered species
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What does it mean when a species is endangered?
A species is considered endangered when its population has declined by 50–70% over ten years, its geographic area is less than 5,000 km2, its population size is less than 2,500 adults, or a statistical prediction estimates it will go extinct within 20 years.
Critically endangered species face an extremely high risk of extinction due to an 80–90% population decline over the previous 10 years, a population size of fewer than 50 individuals, or other factors.
The International Union for Conservation of Nature (IUCN) uses these and other criteria to maintain the Red List of Threatened Species. Human activities, such as habitat loss, invasive species, global warming, pollution, overexploitation, and disease, are the most common factors for species decline.
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What are critically endangered species?
Critically endangered species are those that the International Union for Conservation of Nature (IUCN) has assessed to be facing an extremely high risk of extinction in the wild. It is the most serious designation an imperiled organism can receive from the IUCN, one step below "extinct in the wild."
The IUCN uses five criteria to determine a species' extinction risk, including population decline rate, geographic range, and small population size. In 2022, the IUCN Red List of Threatened Species included over 9,000 critically endangered plants and animals.
Many human activities critically endanger species, such as habitat loss, invasive species, global warming, pollution, overexploitation, and disease.
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How does a species become critically endangered?
A species becomes critically endangered when its population declines drastically due to several factors, often linked to human activities. The International Union for Conservation of Nature (IUCN) uses criteria such as population decline rate, geographic range, small population size, limited distribution, and probability of extinction to classify species.
Human-caused threats include habitat loss from agriculture and infrastructure, competition from invasive species, global warming and pollution, overexploitation through hunting and fishing, and the spread of diseases. Poaching for profit also significantly threatens many species. Conservation efforts involve protecting habitats, managing ecological processes, and controlling invasive species to mitigate these threats.
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What are some examples of critically endangered species?
Critically endangered species are those that face an extremely high risk of extinction in the wild. The International Union for Conservation of Nature (IUCN) uses a system with five criteria to assess a species' extinction risk. These criteria consider population decline rate, geographic range, and probability of extinction.
Several species are classified as critically endangered. Examples include the Bornean, Sumatran, and Tapanuli orangutans. Multiple crocodile species are also critically endangered, such as the Chinese alligator, the Cuban crocodile, and the Orinoco crocodile.
Human activities are the primary drivers of critical endangerment, including habitat loss, invasive species, global warming, pollution, overexploitation, and disease.
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Why is it important to protect critically endangered species?
Critically endangered species face an extremely high risk of extinction in the wild, making their protection vital. Protecting these species is essential because their loss can significantly impact the health and stability of ecosystems. Declining biodiversity lowers an ecosystem’s productivity and reduces its ability to recover from disturbances; the removal of species can destabilize and even cause the collapse of an ecosystem.
Human activities, such as habitat loss, the introduction of invasive species, global warming, pollution, and overexploitation, are the primary drivers of critical endangerment. Conservation efforts involve protecting habitats, removing invasive species, and implementing measures to prevent further decline.
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What actions can people and organizations take to help save critically endangered species?
To help save critically endangered species, people and organizations can protect habitats, remove invasive species, and reduce overexploitation through hunting and harvesting. Protecting habitats involves conserving large areas and sometimes restoring destroyed ones. Removing invasive species includes physically weeding out invasive plants or trapping invasive animals, alongside preventing new threats. Reducing overexploitation can be achieved through enforcing national and international laws that prohibit the killing or collecting of endangered species. Addressing habitat loss, invasive species, global warming and overexploitation are essential for conservation.
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critically endangered species, an endangered species that faces an extremely high risk of extinction in wild habitats, as defined by the International Union for Conservation of Nature (IUCN). The IUCN Red List of Threatened Species is one of the most well-known objective assessment systems for classifying the status of plants, animals, and other organisms threatened with extinction. Of its three categories for threatened species, “critically endangered” is the most serious designation for an imperiled organism, and it is one step below “extinct in the wild.” In 2022 there were more than 9,000 plants and animals listed as critically endangered on the IUCN Red List.
Classification
The IUCN system uses five quantitative criteria to assess the extinction risk of a given species. In general, these criteria consider:
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- The rate of population decline
- The geographic range
- Whether the species already possesses a small population size
- Whether the species has a very small distribution or lives in a restricted area
- Whether the results of a quantitative analysis indicate a high probability of extinction in the wild
Using this framework, a species is categorized as critically endangered if its population has decreased from 80 to 90 or greater percent over the course of 10 years or three generations of the species, whichever comes first. Species also qualify if their likelihood of extinction within this time period exceeds 50 percent. A population census of mature individuals can also indicate critically endangered status: if a species has fewer than 250 mature individuals remaining, or if its number of mature individuals shrinks by at least 25 percent over three years or a single generation, the species is designated critically endangered. A species is also listed as critically endangered if it is found only in an area smaller than 10 square km (about 4 square miles). However, when population size sinks below 50 mature individuals, the area of occupancy criterion is disregarded.
Drivers of critical endangerment
A number of practices perpetrated or exacerbated by humans are critically endangering species and have even spurred a current major mass extinction event, the sixth in Earth’s history. The principal drivers of biodiversity loss are:
- Habitat loss and habitat degradation
- Overexploitation
Although some of these hazards occur naturally, most are caused by humans and their economic and cultural activities. The most pervasive of these threats is habitat loss and degradation—that is, the large-scale conversion of land in previously undisturbed areas driven by the growing demand for commercial agriculture, logging, and infrastructure development.
Invasive species constitute another major threat to critically endangered species. By invading new habitats and outcompeting native species, invasive species limit the success of the native ones. Invasive species pose a threat to about 14 percent of IUCN-classified critically endangered terrestrial vertebrate species. Humans often introduce invasive species to new environments through the exotic pet trade and the transport of goods.
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Modern anthropogenic climate change is an existential threat to many organisms worldwide. Research suggests that global warming could cause a cascading domino effect of extinctions as species that rely on one another disappear (see also trophic cascade). In 2019 the Bramble Cay melomys, a species of rodent, became the first mammal species known to transition from critically endangered to extinct as a direct result of climate change. The species was formally declared extinct as a result of rising sea levels overwhelming its island habitat.
Another force responsible for critically endangering species is overexploitation by humans. This includes the hunting and fishing of animals and the collection of plants and other organisms. Poaching and the illegal wildlife trade have contributed to the decline of many species and can cause populations to lose genetic variation, making them more vulnerable to environmental dangers.
Diseases such as avian flu and Dutch elm disease have been responsible for serious losses of biodiversity. While such diseases are naturally occurring, their spread has often been exacerbated by human activity. Amphibian chytridiomycosis, a devastating fungal disease of frogs and other amphibians, likely spread around the world through global food and pet trading networks; it has been implicated in the critical decline and extinction of frog species around the world.