Endangered Species
Endangered Species are those that are very likely to become extinct in the near future. The International Union for Conservation of Nature (IUCN) has a list known as the "red list" which describes how close animals are to extinction. If you look at the below image, over 42,100 species are threatened with extinction, meaning they are either vulnerable (high risk of extinction), endangered (very high risk), or critically endangered (extremely high risk). Many of these species are threatened due to human activities.
How do species become endangered?
A variety of factors can lead to a species becoming threatened with extinction.
Invasive species can outcompete native species for resources.
Overhunting or overfishing - including poaching of exotic species for tusks, horns, trophies, etc. - can significantly reduce populations.
Habitat destruction (due to urbanization, climate change, deforestation, etc.) can greatly reduce species.
Interspecific competition - the competition for resources between different species - can further decrease the populations of vulnerable species as they are outcompeted.
The same disruption can happen and affect species differently. Some species are better able to adapt, or better able to migrate and find a new habitat, than others. Species that have narrower niches (specialists) have more specific needs, making them less tolerant of changes and more prone to extinction.
As disruptions happen, biodiversity decreases, which can pull species into an extinction vortex where they will be pulled toward extinction via positive feedback. Essentially, what happens is the disturbance reduces the population size, which decreases its genetic variation. As it loses genetic diversity, it loses ecological resilience. When the next disturbance happens, the population is hurt even more. And so on.
There are periods of ecological stress where disruptions to populations are more common. This increases extinction rates.
"Levels" of Extinction
Extinction is when a species completely dies out, but there are different terms that can be used that fall between critically endangered and extinct.
If a species is gone from one area, but still lives in others, it is locally extinct. If the species is completely gone from the wild but remains alive in captivity, it is known as extinct in the wild; these species can be introduced. Also, a functionally extinct species has so few individuals remaining that it no longer makes a viable population and it is only a matter of time until it goes extinct.
Mass Extinction Events
Mass extinction events are characterized by a widespread and rapid decrease in Earth's biodiversity. There have been five previous mass extinction events - the Ordovician-Silurian, Late Denovian, Permian-Triassic, Triassic-Jurassic, and Cretaceous-Paleogene. The Cretaceous-Paleogene Mass Extinction Event occurred about 66 million years ago and is probably the most famous, as it is the one where the dinosaurs went extinct. During this extinction event, roughly 75% of all species went extinct.
We are currently in Earth's 6th mass extinction event, the Holocene Extinction, and it is caused by human activities. This extreme loss of biodiversity is a looming problem, and one that is not to be taken lightly, so I will provide links to where I am getting these numbers for how bleak of a picture it is.
Also known as the Anthropocene Extinction, we are currently facing an extinction rate between 100 and 1,000 times higher than the background rate of extinction, and it is accelerating.
A study published in 2015 estimated that 7% of all living species on Earth may have gone extinct due to this extinction event so far. Global wildlife populations have declined by 69% since 1970, according to a report in 2022 by the World Wildlife Foundation. More than 40% of insect species are declining, with many predicted to go extinct this century, which will have far-reaching effects due to their roles in food webs and pollination.
Roughly 1,000,000 species may face extinction within the coming decades as a result of human activities.
Protecting Endangered Species
There are a variety of strategies enacted by conservation groups, and governments, to help protect animal populations and reduce the risk to threatened species.
One major thing that has been done is the enaction of various pieces of legislation.
The Convention of International Trade of Endangered Species of Wild Fauna and Flora (CITES) is an international agreement where countries are to make agencies that monitor the import and export of endangered species.
The Endangered Species Act is a US law that gives the Fish and Wildlife Service the ability to label species as threatened, create protections for them, and develop recovery plans. A great example of an Endangered Species Act success story is the bald eagle. The protection of their habitats and the banning of the pesticide, DDT, that was bioaccumulating in eagles allowed their populations to rebound.
The Marine Mammal Protection Act was the first US law that strove for conservation in ecosystem management. It protects marine mammals from decline, with different federal entities being responsible for the protection of different species. Humpback whales were nearly driven to extinction by commercial whaling. This law, as well as the International Whaling Commission and the Endangered Species Act, helped to protect the whales and their populations have greatly recovered.
Habitats can be protected through the use of national parks and wildlife sanctuaries.
Poaching can be directly combated with strict laws and even armed guards. When the Northern White Rhino only had one male left, it was under 24-hour protection. The Black Mambas are an all-women anti-poaching group in South Africa that works to protect wildlife.