menghilang dari catatan fosil atau laporan bersejarah mengenai kepunahannya;[1]
populasi yang telah menyusut drastis tidak lagi berperan penting di dalam ekosistem;[2] atau
populasinya tidak dapat lagi dipertahankan. Tidak ada individu yang mampu bereproduksi, atau populasi yang kecil tidak dapat mempertahankan diri akibat depresi perkawinan sekerabat dan hanyutan genetik, yang mengakibatkan hilangnya kecocokan.
Beberapa contoh spesies yang sudah mengalami kepunahan fungsional adalah:
^Caryl-Sue, National Geographic Society, ed. (2013-12-17). "Dec 12, 2006 CE: Chinese River Dolphin Declared Extinct". NationalGeographic.org (dalam bahasa Inggris). Mary Crooks, Yayasan National Geographic. Diarsipkan dari versi asli tanggal 2020-07-02. Diakses tanggal 2019-05-18. On December 12, 2006, biologists declared the baiji (Chinese river dolphin) "functionally extinct." [...] [T]here have been no confirmed baiji sightings in recent years.
^"Yangtze Finless Porpoise". Dana Dunia Untuk Alam (dalam bahasa Inggris). Diakses tanggal 2019-05-18. The Yangtze River, the longest river in Asia, used to be one of the only two rivers in the world that was home to two different species of dolphin—the Yangtze finless porpoise and the Baiji dolphin. However, in 2006 the Baiji dolphin was declared functionally extinct. This was the first time in history that an entire species of dolphin had been wiped off the planet because of human activity.
^Phillips, Tom (2016-10-10). "China's 'extinct' dolphin may have returned to Yangtze river, say conservationists". The Guardian (dalam bahasa Inggris). Beijing, China. Diakses tanggal 2019-05-18. Chinese conservationists believe they may have caught a rare glimpse of a freshwater dolphin that was declared functionally extinct a decade ago having graced the Yangtze river for 20 million years. Scientists and environmentalists had appeared to abandon hope [...] after they failed to find a single animal during a fruitless six-week hunt along the 6,300-km (3,915-mile) waterway in 2006. [...] [T]he unconfirmed sighting occurred during a seven-day search mission down the Yangtze that began in the city of Anqing on 30 September [2016].
^Xiang, Luan (2018-05-08). ZD, ed. "Feature: Hope prevails for the baiji dolphin's comeback" (dalam bahasa Inggris). Beijing, China: XiahuaNet. Diarsipkan dari versi asli tanggal May 8, 2018. Diakses tanggal 2019-05-18. Earlier this week, the China Biodiversity Conservation and Green Development Foundation (CBCGDF) released a photograph of a baiji lookalike, captured last month in a section of the Yangtze near Wuhu in the eastern province of Anhu. [...] The institute said it would be imprudent to identify the animal in a photograph without further evidence. Nonetheless, it is too soon to label the species "extinct."Parameter |url-status= yang tidak diketahui akan diabaikan (bantuan)
^Smith, B.D.; Wang, D.; Braulik, G.T.; Reeves, R.; Zhou, K.; Barlow, J.; Pitman, R.L. (2017). "Lipotes vexillifer. The IUCN Red List of Threatened Species 2017: e.T12119A50362206" (dalam bahasa Inggris). doi:10.2305/IUCN.UK.2017-3.RLTS.T12119A50362206.en.
^"White Rhino". Dana Dunia Untuk Alam (dalam bahasa Inggris). Diakses tanggal 2019-05-18. As of March 2018, there are only two rhinos of the northern white rhino left, both of which are female.
^"Ivory-billed Woodpecker Campephilus principalis"(PDF). Multi-Species Recovery Plan for South Florida (dalam bahasa Inggris). Birds (Ivory-billed woodpecker): 4–465 to 4–472. 2019-05-03 [1999]. Diarsipkan dari versi asli(PDF) tanggal 2020-07-15. Diakses tanggal 2019-05-18.
^Schulz, Martin (2004). National Recovery Plan for the Christmas Island Shrew (Crocidura attenuata trichura) (dalam bahasa Inggris). Australian Government, The Department of the Environment and Energy. ISBN0-642-55011-5. The Christmas Island Shrew was thought to be extinct until the accidental separate finding of two individuals in 1985... Information indicating the unconfirmed capture of two other shrews in 1958 when South Point (approx.: 10°33'S, 105°39'E) was being cleared for mining was provided by D. Powell (pers.comm. 1997 cited in Meek 1998).
^Platt, John R. (2014-12-23). "Holiday Species Snapshot: Christmas Island Shrew" (dalam bahasa Inggris). Scientific American. Diakses tanggal 2019-05-18. There's an official species recovery plan in place, though, just in case the shrews ever show up again. Sadly, that seems like it would require a Christmas miracle.
^Woinarski, J.; Burbidge, A.A.; Lumsden, L. (2016). "Crocidura trichura. The IUCN Red List of Threatened Species 2016: e.T136379A22304640" (dalam bahasa Inggris). doi:10.2305/IUCN.UK.2016-3.RLTS.T136379A22304640.en.
^Platt, John R. (2016-01-26). "The Yangtze Giant Softshell Turtle Just Got 25 Percent Closer to Extinction" (dalam bahasa Inggris). Scientific American. Diakses tanggal 2019-05-18. The massive turtle known as Cu Rua... passed away last week. [...] Cu Rua was one of the last four Yangtze giant softshell turtles (Rafetus swinhoei) left in the world. Now only three remain: a turtle of unknown gender in another lake outside of Hanoi and a male-female pair in China.
^Gibbens, Sarah (2017-05-23). "There Are Only 3 of These Turtles Left on Earth". National Geographic (dalam bahasa Inggris). Diakses tanggal 2019-05-18. In the waters of the Yunnan Province of China, a team of conservationists is hoping to find a turtle with some very valuable sperm. [...] A male and female are in captivity in the Suzhou Zoo in China, and one wild turtle lives in a Vietnamese lake called Dong Mo. [...] In February of [2016], a fourth turtle... died in captivity in Vietnam, reducing the world population by a quarter.
^Wang, Serenitie (2019-04-15). "One of world's most endangered turtles dies, leaving 3 left". CNN (dalam bahasa Inggris). Beijing, China. Diakses tanggal 2019-05-18. The last known female Yangtze giant softshell turtle has died in China, according to Chinese state media, potentially dooming the species to extinction. [...] Now, there are only three left in the world, according to the Suzhou Daily.
^Smith, Nicola (2019-04-15). "Turtle species on brink of extinction as last-known female dies in China". The Daily Telegraph (dalam bahasa Inggris). Diakses tanggal 2019-05-18. One of the world’s rarest turtles, a Yangtze giant softshell, has died in a Chinese zoo, leaving only three of the critically endangered species left. The turtle was the last confirmed female in the world when she died during fertility treatment, raising the grim prospect that the species, which is also known as the Red River giant and is native to China and Vietnam, may now be functionally extinct.
^"South China Tiger". Dana Dunia Untuk Alam (dalam bahasa Inggris). Diakses tanggal 2019-05-18. The South China tiger population was estimated to number 4,000 individuals in the early 1950s. [...] By 1996 the population was estimated to be just 30-80 individuals. Today the South China tiger is considered by scientists to be “functionally extinct,” as it has not been sighted in the wild for more than 25 years.
^AFP (2016-04-06). "Tigers declared extinct in Cambodia". The Guardian (dalam bahasa Inggris). Diakses tanggal 2019-05-18. The last tiger was seen on camera trap in the eastern Mondulkiri province in 2007, [the World Wildlife Fund] said. “Today, there are no longer any breeding populations of tigers left in Cambodia, and they are therefore considered functionally extinct,” the conservation group said in a statement.
^Nyhus, P. (2008). "Panthera tigris ssp. amoyensis. The IUCN Red List of Threatened Species 2008: e.T15965A5334628" (dalam bahasa Inggris). doi:10.2305/IUCN.UK.2008.RLTS.T15965A5334628.en.
