Red adder (Bitis rubida)
|Size||Male length: up to 335 mm (2)|
Female length: up to 386 mm (2)
This species has not yet been classified by the IUCN. The red adder belongs to the Bitis cornuta-inornata species complex, an enigmatic group of rare dwarf adders consisting of five similar species whose taxonomy has only recently been revised (3).
First described in 1997 (4), this small adder is characterised by orange-brown colouration that strongly camouflages it against the sandy substrate of its habitat. Although this reddish colouration is thought typical of the species, earning the snake its common name, markings and colouration are highly variable, and darker, patterned specimens also exist (5). The body of patterned individuals is greyish-brown with rows of darker, blackish blotches running down its length, more conspicuous above and paler on the sides, between which there may be a series of contrasting pale bluish patches. These patterned red adders closely resemble the southern adder (Bitis armata), but can be distinguished by having many more scales on their underside (3). Like some other species of the cornuta-inornata complex, the red adder has distinctive tuft-like scales protruding above each eye and a broad, triangular head, typical of viperids (6) (7).
This South African endemic has a disjunct distribution from the Cederberg Mountains in the west, across the Cape Fold Mountains, to an isolated population in the Swartberg Range in the east (5) (6).
The red adder is strongly associated with rocky mountain fynbos habitat, particularly on the warmer and drier mountains of the Western Cape (5) (6). Fynbos is a unique ecosystem characterised by sandstone soils and scrub vegetation. Across its range, this snake is usually found at altitudes well over 1000 metres above sea level, with the Swartberg population typically at 1350 metres (5).
The red adder is a poorly understood species that is only active during the morning (5). However, a recently initiated study of the snake has revealed some interesting new behaviours. Although previously thought that none of the species complex used sidewinding locomotion, the study has shown that the red adder is in fact a very proficient sidewinder (8). Valuable data on the adder’s diet has also been obtained, showing that it primarily preys on lizards (9).
Bitis species are all believed to be ovoviviparous, giving birth to live young (7).
All five species belonging to the Bitis cornuta-inornata complex are vulnerable to habitat loss as a result of development and wild fires, and also illegal collecting for the pet trade (5).
The Swartberg red adder population has been studied since September 2004 by Dr. Tony Phelps and Johannes Els of the Cape Reptile Institute. Observations so far have revealed important facts about the snake’s diet, morphology, and behaviour. The study is ongoing, and it is hoped that further findings on population structure, spatial distribution and biology will provide important insight into the status of these little known adders, which will in turn aid management and future conservation measures (5).
Authenticated (11/07/2006) by Dr. Tony Phelps, Squamate Ecologist and founder of the Cape Reptile Institute.
- Endemic: a species or taxonomic group that is only found in one particular country or geographic area.
- Fynbos: the scrubland characteristic of the Western Cape area of South Africa, consisting of bushes with hard leaves, and resembling heaths.
- Ovovivipary: method of reproduction whereby the egg shell is weakly formed and young hatch inside the female; they are nourished by their yolk sac and then ‘born’ live.
- Species complex: a group of closely related species that satisfy the scientific definition of species - that is, they are reproductively isolated from each other - but which are anatomically very similar. The individual species within the complex can often only be separated using methods from molecular genetics such as DNA barcoding.
UNEP-WCMC (May, 2006)
Sean Thomas (July, 2006)
- Branch, W.R. (1999) Dwarf adders of the Bitis cornuta-inornata complex (Serpentes:Viperidae) in South Africa. Kaupia, 8: 39 - 63.
- Branch, W.R. (1997) A new adder (Bitis; Viperidae) from the Western Cape Province, South Africa. South Afr. J. Zool., 32(2): 37 - 42.
- Phelps, T. (2006) Pers. comm.
Survey of Cederberg Amphibians and Reptile for Conservation and Ecotourism (SCARCE) (June, 2008)
The EMBL Reptile Database (June, 2008)
- Phelps, T. (01/01/0001 00:00:00) Bitis rubida (Branch, 1997). Red Adder. Sidewinding Behaviour. Afr. Herp. News,.
- Phelps, T. and Els, J. (01/01/0001 00:00:00) Bitis rubida (Branch, 1997). Red Adder. Diet and Morphological Information. Afr. Herp. News,.