A rare species is a group of organisms that are very uncommon, scarce, or infrequently encountered. This designation may be applied to either a plant or animal taxon, and is distinct from the term endangered or threatened. Designation of a rare species may be made by an official body, such as a national government, state, or province. The term more commonly appears without reference to specific criteria. The International Union for Conservation of Nature does not normally make such designations, but may use the term in scientific discussion.^[1]

Rarity rests on a specific species being represented by a small number of organisms worldwide, usually fewer than 10,000. However, a species having a very narrow endemic range or fragmented habitat also influences the concept.^[2][3] Almost 75% of known species can be classified as "rare".^[4]

Rare species are species with small populations. Many will move into the endangered or vulnerable category if the negative factors affecting them continue to operate. Well-known examples of rare species - because these are large terrestrial animals - include the Himalayan brown bear, Fennec fox, Wild Asiatic buffalo, or the Hornbill.

They are not endangered yet, but classified as "at risk",^[5][6] although the frontier between these categories is increasingly difficult to draw given the general paucity of data on rare species. This is especially the case in the world Ocean where many 'rare' species not seen for decades may well have gone extinct unnoticed, if they are not already on the verge of extinction like the Mexican Vaquita.^[7]

A species may be endangered or vulnerable, but not considered rare if it has a large, dispersed population. IUCN uses the term "rare" as a designation for species found in isolated geographical locations. Rare species are generally considered threatened because a small population size is less likely to recover from ecological disasters.

A rare plant's legal status can be observed through the USDA's Plants Database.

Rare species

Name		Image	IUCN Red List conservation status	Last sighting	Estimated population					Endemic geographic location
Common name	Scientific name				Lowest wildlife	Highest wildlife	Captive	Total lowest	Total highest
Ethiopian amphibious rat	Nilopegamys plumbeus		Critically Endangered, Possibly Extinct	1927	?	?	0	?	?
Zuniga's melanomys	Melanomys zunigae		Critically Endangered, Possibly Extinct	1949	?	?	0	?	?	Lima Department, Peru
De Winton's golden mole	Cryptochloris wintoni		Critically Endangered, Possibly Extinct	c. 1950	?	?	0	?	?
Northern Sumatran rhinoceros	Dicerorhinus sumatrensis lasiotis		Critically Endangered, Possibly Extinct	After 1960 1	?	?	0	?	?	Myanmar & Malay Peninsula, Malaysia / Thailand
Christmas Island shrew	Crocidura trichura		Critically Endangered, Possibly Extinct	1986	?	?	0	?	?	Christmas Island
Cuban ivory-billed woodpecker	Campephilus principalis bairdii		Critically Endangered	16 March 1987	?	?	0	?	?	Cuba
Garrido's hutia	Capromys garridoi		Critically Endangered, Possibly Extinct	1989	?	?	0	?	?	Banco de los Jardins y Jardinillos, Canarreos Archipelago, Cuba
Angel Island mouse	Peromyscus guardia		Critically Endangered, Possibly Extinct	1991	?	?	0	?	?
Emma's giant rat	Uromys emmae		Critically Endangered, Possibly Extinct	1994	?	?	0	?	?	Owi Island, Indonesia
Wimmer's shrew	Crocidura wimmeri		Critically Endangered	2008	?	?	0	?	?
Baiji	Lipotes vexillifer		Critically Endangered, Possibly Extinct	2018	?	?	0	?	?
Puebla deer mouse	Peromyscus mekisturus		Critically Endangered, Possibly Extinct	1948	0	50	0	0	50
Dwarf hutia	Mesocapromys nana		Critically Endangered, Possibly Extinct	26 October 1951	0	50	0	0	50	Zapata Swamp, Cuba
New Zealand greater short-tailed bat	Mystacina robusta		Critically Endangered, Possibly Extinct	1967	0	50	0	0	50
Kouprey	Bos sauveli		Critically Endangered, Possibly Extinct	1988	0	50	0	0	50
Montane monkey-faced bat	Pteralopex pulchra		Critically Endangered, Possibly Extinct	17 May 1990	0	50	0	0	50
San Felipe hutia	Mesocapromys sanfelipensis		Critically Endangered, Possibly Extinct	1978	0	99	0	0	99	Cayo de Juan Garcia & Cayos de San Felipe, Cuba
Gloomy tube-nosed bat	Murina tenebrosa		Critically Endangered, Possibly Extinct	1962	1	1	0	1	1	Tsushima Island & Yakushima, Japan
Fernandina Island Galápagos tortoise	Chelonoidis niger phantasticus		Critically Endangered, Possibly Extinct	N/A	1	5	0	1	5	Fernandina Island, Ecuador
Aru flying fox	Pteropus aruensis		Critically Endangered, Possibly Extinct	1887	1	49	0	1	49	Trangan, Indonesia
Horrid ground-weaver	Nothophantes horridus		Critically Endangered	N/A	9	9	?	9	9	Cattedown, Plymouth, United Kingdom of Great Britain and Northern Ireland
Northern white rhinoceros	Ceratotherium simum cottoni		Critically Endangered (Possibly Extinct in the Wild)	N/A	? 2	? 2	2 2	2 2	2 2
One-striped opossum	Monodelphis unistriata		Critically Endangered, Possibly Extinct	9 April 1899	2	10	0	2	10
Yangtze giant softshell turtle	Rafetus swinhoei		Critically Endangered	N/A	2	4	1	3	5
American ivory-billed woodpecker	Campephilus principalis principalis		Critically Endangered	8 April 2022	3 (as of 8 April 2022)[8]	3 (as of 8 April 2022)[8]	0	3 (as of 8 April 2022)[8]	3 (as of 8 April 2022)[8]
Guadalcanal rat	Uromys porculus		Critically Endangered, Possibly Extinct	Between 1886 and 1888	3	3	0	3	3
Emperor rat	Uromys imperator		Critically Endangered, Possibly Extinct	c. 1960s	3	3	0	3	3
Key tree-cactus	Pilosocereus robinii		Critically Endangered	N/A	7	15		7	15	Florida Keys, Mexico, Puerto Rico
Lord Howe Island stick insect	Dryococelus australis		Critically Endangered	N/A	< 10 (as of 3 October 2021)[9]	< 10 (as of 3 October 2021)[9]		< 10 (as of 3 October 2021)[9]	< 10 (as of 3 October 2021)[9]	Ball's Pyramid, Australia
Vaquita	Phocoena sinus		Critically Endangered	N/A	10 (as of 5 May 2022)[10]	10 (as of 5 May 2022)[10]	0	10 (as of 5 May 2022)[10]	10 (as of 5 May 2022)[10]
Saola	Pseudoryx nghetinhensis		Critically Endangered	2013	20 (as of 30 October 2021)[11]	< 100 (as of 20 August 2021)[12]	0[13]	20 (as of 30 October 2021)[11]	< 100 (as of 20 August 2021)[12]
Telefomin cuscus	Phalanger matanim		Critically Endangered, Possibly Extinct	1997	40	40	0	40	40
Gobi bear	Ursus arctos gobiensis		Critically Endangered	N/A	51 (as of 27 May 2022)[14]	51 (as of 27 May 2022)[14]	0[15]	51 (as of 27 May 2022)[14]	51 (as of 27 May 2022)[14]
Māui dolphin	Cephalorhynchus hectori maui		Critically Endangered	N/A	55	55		55	55
Cat Ba langur	Trachypithecus poliocephalus		Critically Endangered	N/A	65	67		65 (as of March 2018)[16]	67 (as of March 2018)[16]
Indonesian Javan rhinoceros	Rhinoceros sondaicus sondaicus		Critically Endangered	N/A	76 (as of 20 September 2022)[17]	76 (as of 20 September 2022)[17]	0	76 (as of 20 September 2022)[17]	76 (as of 20 September 2022)[17]
Western Sumatran rhinoceros	Dicerorhinus sumatrensis sumatrensis		Critically Endangered	N/A	75 (as of 18 December 2022)[18]	85 (as of 18 December 2022)[18]	10	85	95
Alagoas curassow	Mitu mitu		Extinct in the wild	N/A		0	130	130	130
Kākāpō	Strigops habroptilus		Critically Endangered	N/A	149	149		149	149	Anchor Island, Codfish Island / Whenua Hou, Little Barrier Island and Maud Island, New Zealand
Philippine eagle	Pithecophaga jefferyi		Critically Endangered	N/A	200 breeding pairs	200 breeding pairs		200 breeding pairs	200 breeding pairs
Cross River gorilla	Gorilla gorilla diehli		Critically Endangered	N/A	200	300	0	200	300
Bornean rhinoceros	Dicerorhinus sumatrensis harrissoni		Critically Endangered	N/A	< 250 (as of 24 February 2020)[19]	< 250 (as of 24 February 2020)[19]	0	< 250 (as of 24 February 2020)[19]	< 250 (as of 24 February 2020)[19]	East Kalimantan, Indonesia & Sarawak, Malaysia
Malabar large-spotted civet	Viverra civettina		Critically Endangered, Possibly Extinct	1993	249	249	0	249	249
Devils Hole pupfish	Cyprinodon diabolis		Critically Endangered	N/A		263 (as of 29 September 2022)[20]	300 (as of 11 May 2022)[21]	475 (as of 4 May 2022)[22]	475 (as of 4 May 2022)[22]	Devils Hole, Death Valley National Park, United States of America
North Atlantic right whale	Eubalaena glacialis		Critically Endangered	N/A	366	366		366	366
Black softshell turtle	Nilssonia nigricans		Critically Endangered	N/A	150	150	300	450	450	Sultan Bayazid Bastami shrine at Chittagong
California condor	Gymnogyps californianus		Critically Endangered	N/A	446	446		446	446
Central rock rat	Zyzomys pedunculatus		Critically Endangered	N/A	800	800	0	800	800
Wild Bactrian camel	Camelus ferus		Critically Endangered	N/A	950	950		950	950
Eastern lowland gorilla	Gorilla beringei graueri		Critically Endangered	N/A	< 5,000 (as of 7 October 2022)[23]	< 5,000 (as of 7 October 2022)[23]	1	< 5,000 or 5,000	< 5,000 or 5,000

Notes:

• ¹ Last recorded that 7 were in captivity in 1960, in zoos, circuses etc., in the International Zoo Yearbook II. Reports that there is a small population left in Malay Peninsula and Myanmar.
• ² On 19 March 2018, the last known Northern white rhinoceros male died, but his and another male's sperm was collected and has been used to fertilize eggs as part of a de-extinction effort. Last two known Northern white rhinoceros are both female and held in captivity in the Ol Pejeta Conservancy, Kenya. Unknown if anymore exist in the wildlife and if none exist in the wildlife they would be functionally extinct.

See also

• Abundance (ecology)
• Biodiversity Action Plan
• Chelonoidis nigra abingdonii
• Common species
• Critical depensation
• Endangered Species Recovery Plan
• Rare Species Conservation Centre

References

External links

• USDA Plant Database

Further reading

• Gorbunov, Y. N., Dzybov, D. S., Kuzmin, Z. E. and Smirnov, I. A. 2008. Methodological recommendations for botanic gardens on the reintroduction of rare and threatened plants. Botanic Gardens Conservation International (BGCI).