Environment

When Is A Species Declared To Be Functionally Extinct?

Extinction is a biological term that describes the termination of a whole group of a species such that they cannot be found anywhere on the planet, or the surviving members no longer have the ability to propagate their species.

Extinction is a biological term that describes the termination of a whole group of a species such that they cannot be found anywhere on the planet, or the surviving members no longer have the ability to propagate their species. The term “Functionally Extinct” describes a situation where a species still exists but is unable to play any role in the ecosystem due to population decline or disruption in their gene flow. Since 1900, about 477 species of animals have gone extinct already thanks to human activities. Of these extinct species, 158 of them are fish species, 146 amphibians, 80 species of birds, 69 species of mammals, and 24 species of reptiles. For a species to be declared functionally extinct, certain conditions have to be met first. These conditions include the following

The animal disappears from the fossil record

A Fossil Record refers to the impression or trace left behind by a once-living organism. Once the sighting or a historical report of a given species ceases, then that species meets the threshold of being declared functionally extinct. The period it takes for this to come into effect is usually ten years. Once a decade elapses without any sighting or report, then the status of the animal becomes extinct.

The animal has a reduced role in the ecosystem

Every living organism has a role to play in the cycle of life, a position in the natural order of things called the food chain. Once the populations of a particular species decline to levels too low for them to add any value to this cycle, then they qualify to be declared functionally extinct.  

The animal is no longer viable

The survival of a species wholly depends on its ability to continually reproduce in a manner that keeps their populations stable or higher over some time. Once members of a species are unable to reproduce or when the rate of reproduction is not fast enough to sustain the species due to genetic shifts, then that species can be declared functionally extinct. 

A reduction in the area the species inhabit

Animal species need space to find food and mates during the breeding season. The bigger the population of a species is, the bigger the territory occupied. As they continue multiplying, the size of their habitat also increases accordingly to reduce competition for food and other needs. When the population of a species starts declining, their territories begin to shrink, and sighting them in the wild becomes harder. The shrinking can be used as an indicator of their status in the ecosystem.

A reduction in adult populations

According to National Geographic, a population with less than 2,500 adults is considered an endangered species. Similarly, a species that experience a population decline of at least 20% in a within two generations or five years is regarded as endangered. Further decline would render them functionally extinct.

Some of the functionally extinct animals in the current timeline include the following:

Panamanian Golden Frog

The frog was once prevalent in the cloud forests of Panama before its numbers were brought to dangerously low levels by the amphibian chytridiomycosis disease. The diseases not only affected the Panama golden frog but other frog species in the region as well. The frog has not been seen in the wild since 2006 and can only be found in zoos and sanctuaries. There are about 1,500 individuals left in the world right now.

Butterfly Splitfin

The small fish was once spread out in the Rio Ameca region of Mexico until the construction of a dam that destroyed their habitat downriver. The butterfly splitfin is among the unique fish species that give birth to live ones. They are only found in private aquariums and fish sanctuaries. None so far has been sighted in the wild for a while now.

Baiji Dolphin

The Baiji is a freshwater dolphin that was mostly found in China and has not been sighted since 2002 when the last known living baiji died. In 2007 a Chinese man was alleged to have videotaped the Baiji in the Yellow River. The video has fueled hope that there may be some left in the wild. 

The Northern White Rhino

The northern white rhino once roamed the East and Central regions of Africa, numbering about 3,000 in 1900. Poaching by humans has brought down their numbers to only two individuals and both females. The two are living in the Ol Pejeta conservancy in Kenya.

South China Tiger

One of the original nine tiger species, the South China tiger, has not been seen in the wild since 1996, and the only surviving members are in captivity. The tigers were once spread out in the Zhejiang province but can now be found in zoos only in unknown numbers.

Bornean Rhinoceros

A member of the Sumatran rhinoceros and much smaller than their African cousins, the Bornean Rhinoceros was declared extinct in the wild in 2015 and now has only two female individuals left in captivity. A wild female rhino was however captured in 2016, and there is hope that a number of them still exist somewhere in the wild.

Yangtze Giant Softshell Turtle

Once found in the whole of Southern China and Northern Vietnam, there are only three living individuals left, one in captivity in China and two in the Vietnamese wild. The last viable breeding female died in 2019 at the Suzhou Zoo, which effectively rendered the species functionally extinct. Unless another female is found soon, the giant turtle is well on its way to being declared extinct in a few years.

The Future Of Functionally Extinct Species

Once a species has been declared functionally extinct, the chances of making a comeback are usually slim since their viability at most times is beyond help. The future of the northern white rhino, for instance, is all but sealed, with no living male their chances of reproduction just hit zero. The best course of action in these situations is to protect the last living individuals to their last days in the hopes that other members of their species are hidden somewhere in the wild awaiting discovery.

About the Author

Benjamin Elisha Sawe holds a Bachelor of Arts in Economics and Statistics and an MBA in Strategic Management. He is a frequent World Atlas contributor. 

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