Chironius vincenti 

Scope: Global
Language: English

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Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Chordata Reptilia Squamata Colubridae

Scientific Name: Chironius vincenti (Boulenger, 1891)
Common Name(s):
English St Vincent Blacksnake
Herpetodryas carinatus ssp. vincenti Boulenger, 1891

Assessment Information [top]

Red List Category & Criteria: Critically Endangered B1ab(iii) ver 3.1
Year Published: 2016
Date Assessed: 2015-07-20
Assessor(s): Daltry, J.C., Henderson, R.W. & Powell, R.
Reviewer(s): Bowles, P.
Contributor(s): Hedges, B. & Hanson, S.
Facilitator/Compiler(s): NatureServe
Listed as Critically Endangered on the basis that this species has an extent of occurrence of 22 km2 and an area of occupancy of at most 12 km2, and more likely below 10 km2. It is known from a single location, Cumberland, based on a threat from habitat destruction and likely from invasive mammals. and there is a projected continuing decline in the extent and quality of its habitat once road development and associated land clearance begins.
Previously published Red List assessments:

Geographic Range [top]

Range Description:This snake is endemic to St. Vincent, occurring from 275 to 600 m asl (Henderson and Powell 2009). It appears to have a highly localized distribution, which includes the Vermont Nature Reserve. A record from Kingston is dubious (R. Henderson pers. comm. 2015). A record on the east coast is accepted in the extent of occurrence calculation, but is unlikely to be correct as the forest habitat at this locality is atypical for blacksnakes (R. Henderson and R. Powell pers. comm. 2015). The Cumberland Forest Reserve may well be the extent of its range ( The area of occupancy is unlikely to exceed the combined area of Important Bird Areas on the island (R. Powell pers. comm. 2015).
Countries occurrence:
Saint Vincent and the Grenadines
Additional data:
Estimated area of occupancy (AOO) - km2:12
Number of Locations:1
Lower elevation limit (metres):275
Upper elevation limit (metres):600
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population:This is a rare species, and was at one point thought to be extinct. The Forestry Department collected a specimen in 1987, and it has since been recorded several times (R. Henderson pers. comm. 2015), most recently in 2005. This species occurs in well-surveyed habitats regularly visited by researchers working on the St. Vincent Parrot, but has never been recorded in these surveys (R. Powell pers. comm. 2015). Natural rarity is very unusual on Caribbean islands, where species diversity is often relatively low and there is little competition (J. Daltry pers. comm. 2015), and so it seems likely that this species is rare as a result of historical and ongoing pressures. As the species is so rare, however, it is unknown whether populations are still in decline or presently stable, and the causes of any decline in apparently good forest are unknown (R. Henderson pers. comm. 2015).
Current Population Trend:Unknown
Additional data:

Habitat and Ecology [top]

Habitat and Ecology:This is a wet forest inhabitant (Henderson and Powell 2009). It is known to occur on steep slopes; it is unknown whether it is restricted to these areas (R. Henderson pers. comm. 2015). The habitat is presently well-preserved within protected areas that are also home to the higher-profile St. Vincent Parrot, affording it a degree of protection. The diet consists of frogs, and these do not appear to be under particular pressure.
Continuing decline in area, extent and/or quality of habitat:Yes

Use and Trade [top]

Use and Trade: There is no known use or trade in this species.

Threats [top]

Major Threat(s): This species may be at risk from marijuana plantations, which clear areas within the forest and are difficult to control, but it is unknown whether these are a pressure to specific localities where this snake occurs (R. Henderson and J. Daltry pers. comm. 2015). Forest cover on St Vincent has decreased by an estimated 3-5% annually, driven partly by agriculture, residential development and illegal squatting, since the 1990s (Ministry of Health and Environment 2010). This species is likely to be at specific risk from planned road development through the centre of St. Vincent, which will bisect the forest and open areas for housing development (; this project has been under discussion for some time and no clear timeline exists for road construction. The Small Asian Mongoose is a general threat to terrestrial snakes on islands and has been established on St. Vincent since the 1870s (J. Daltry pers. comm. 2015); this may be responsible for the species' current rarity (R. Powell pers. comm. 2015).

Conservation Actions [top]

Conservation Actions: This species occurs in at least one protected area, and a large proportion of the remaining suitable habitat on the island is protected (R. Henderson pers. comm. 2015). While the species occurs in a well-surveyed area, these do not specifically target snakes and targeted research is recommended to obtain more information on this snake and identify possible causes of its rarity.

Errata [top]

Errata reason: This errata assessment has been created because the map was accidentally left out of the version published previously.

Citation: Daltry, J.C., Henderson, R.W. & Powell, R. 2016. Chironius vincenti. (errata version published in 2017) The IUCN Red List of Threatened Species 2016: e.T4672A115069815. . Downloaded on 21 October 2017.
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