Rationale
(Changed due to Same category but change in criteria)
Has a small range (extent of occurrence = 17, 421 km2) below the Vulnerable threshold and is severely fragmented. The Southern Adder is confined to a particular habitat type, which, outside of protected areas, is threatened by urbanization and agriculture. It has suffered extirpation in several areas near Cape Town presumably due to urbanization. Because the range is severely fragmented, continues to decrease in size and quality, and because the number of subpopulations is also decreasing (local extinction of Cape Town population), this species is considered Vulnerable.
Distribution
Endemic to the Western Cape, South Africa (Bates et al. 2014). Found in two disjunct coastal regions: around Langebaan Peninsula on the West Coast, and from the Bot River area to the Breede River mouth on the south Cape coast (Bates et al. 2014). The latter region appears to contain several isolated subpopulations. Branch’s (1999) Potberg record for Bitis cornuta is considered to be referable to B. armata as there are recent records of this species from that locality (Bates et al. 2014). Populations around Cape Town have not been seen in approximately 40 years and are considered extirpated as a result of the intense transformation of this region for urban development. This loss is apparent from the South African National Landcover datasets from 1990 and 2013 (Geo Terra 2015, 2016). Comparison of these landcover data show there is more than 5% natural landcover loss within the distribution of this species in this 23 year time period. This is much greater than the 2.3% natural landcover decrease on a national scale.
Decline
Occurs in several disjunct populations, and habitat is fragmented by developments.
Population trend
Trend
No quantitive information on population size is currently available. Population trends all inferred from losses in habitat and apparent reductions in number of populations.
Threats
Threatened primarily by urbanization and agriculture. It is vulnerable to further loss of habitat and population declines because of its restricted distribution and confinement to a particular habitat type in coastal areas that might undergo further development
Uses and trade
This species is known to be in the pet trade with some evidence of illegal collection (A. Turner pers. comm., 2018). It is not known how many individuals are sourced from the wild or from captive stock.
Conservation
Protection of additional habitat through private conservation initiatives could assist to protect populations that currently fall outside protected areas, especially if this assisted in setting up corridors between suitable habitat. Population size estimates for populations in protected areas would assist to monitor declines. Because there have been documented extirpations, this species might be a candidate for a Biodiversity Management Plan (see South African National Environmental Management Biodiversity Act, Act No. 10 of 2004).
