Cape Cobra

Cape Cobra
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Reptilia
Order:	Squamata
Suborder:	Serpentes
Family:	Elapid
Genus:	Naja
Species:	N. nivea
Binomial name
Naja nivea (Linnaeus, 1758)
Synonyms
Naja flava Merrem

The Cape Cobra or yellow cobra (Naja nivea) is a moderately sized, highly venomous cobra inhabiting a wide variety of biomes across Southern Africa. The Cape Cobra is also known as the "geelslang" (yellow snake) and "bruinkapel" (brown cobra). Afrikaans speaking South Africans refer to the Cape Cobra as "koperkapel", mainly because of a rich yellow color variation.

Description

The Cape cobra is a relatively small species of cobra. Specimens typically average around 1.23 metres (4.0 ft) or 120 cm long but it may grow up to a maximum size of 1.85 metres (6.1 ft) or 180 cm long, but this is rare.^[1][2] Males are slightly larger than females. The largest recorded specimen was a male found in De Hoop Nature Reserve with a total length of 1.85 metres (6.1 ft).^[1] Their colouration varies greatly. This species shows a wide range of colour variation; from yellow and golden brown to dark brown and even black. In addition, individuals show a varying degree of black or pale stippling and blotches, and although it has been stated that colour and marking are geographically related, it is also possible to observe virtually all colour varieties at one location. For example, it is well known that the Kalahari Desert specimens in Botswana and Namibia are usually more consistently yellow than the more southerly populations (Spawls & Branch, 1995; Branch, 1998). However, at DeHoop, and other specific locations in the Western Cape, all colour variations have been recorded.^[1][3]

Scalation

Dorsal scales on the midbody 21, ventral scales 195-227, Subcaudal scale is paired, subcaudal scales 50-68, anal plate is single, upper labials 7, upper labials to the eye 3+4, preoculairs 1, postoculairs 3 but can also be 4, lower labials 9 (8 – 10), and temporal 1+2 variable.^[2]

Geographic Range

This species is found mainly in South Africa and in parts of Namibia, Botswana, and Lesotho.^[1] In South Africa, they can be found throughout the Cape Province, Free State Province, and southwestern Transvaal. They are also found in the Kalahari desert, particularly in the southern regions of the Kalahari.^[2]

Habitat

Although the Cape cobra has the smallest geographical range of any other African cobra, it occurs in a variety of different habitats.^[2] This species is mostly found in temperate regions, arid karroid regions, particularly along rivers and streams entering well drained open areas. In Lesotho, they can even be found in altitudes as high as 2,700 metres (8,900 ft) above sea level. They occur in forest and high grassland areas of Free State province. It can also be found in rocky hills of the Cape and in desert and semi-desert areas of its geographical range.^[3][2] Cape cobras are also known to venture into villages and cities where they may come in direct contact with humans.^[3]

Behavior and Diet

The Cape cobra is a timid snake, always seeking to escape when encountered, although when aroused it has been described as willing to bite readily, but the species in general is described as not being aggressive as some other African snakes, such as the Black mamba or the Saw-scaled viper (Spawls & Branch, 1995; Branch, 1998; Marais, 2004).^[1] It has also been stated that the Cape cobra is more aggressive during the mating period (Broadley, 1983; Spawls & Branch, 1995). The Cape cobra is a diurnal species and actively forages throughout the day. During very hot weather it may become crepuscular, but is rarely if ever observed during the hours of darkness (Pers obs.).^[3][1]

The Cape cobra is a feeding generalist.^[1] It feeds on a wide spectrum of prey, including other snakes, rodents, lizards, birds, and carrion. Recorded prey items for this species at DeHoop from October 2004 to March 2006 showed that 31% of the species' diet consisted of rodents, 20% was other snakes (including juvenile and small adult Puff adders), 11% lizards, 11% birds, 16% carrion, and 11% "conspecifics". In the same study period conducted at DeHoop, Cobras were seen scavenging and feeding on carrion on two occasions (Phelps, 2006).^[4] Both were road-killed snakes, the first, an adult P. rhombeatus, the second an adult Karoo whip snake, Psammophis notostictus.

There is no recent research or information with regard to size of home range, population densities, or sex ratio. Detailed accounts of such as reproductive and feeding behaviour are also lacking, and past and current information has tended to be anecdotal, or repetitive in popular literature. For example, the accounts of the Cape cobra climbing and preying on sociable weaver (Philetaurus socius) in the Kalahari as been quoted several times (MacLean, 1973).^[1][3]

Predators

Predators of the Cape cobra include the honey badger (Ratel), various birds of prey such as Secretary birds, eagles and falcons, different species of Mongoose (including the Yellow mongoose, Cape Gray Mongoose, and even Meerkats). Other snakes such as the Black mamba and the Olive Whip snake (Psammophis mossambicus) also occasionally prey on the Cape cobra. Cape cobra's are also often killed by humans when they venture into human settlements.^[1][3][2]

Venom

The Cape cobra's venom is made up of postsynaptic neurotoxins and might also contain cardiotoxins,^[5] that affect the respiratory system, nervous system, and heart. The LD₅₀ for this species' venom is 0.72 mg/kg.^[3][6] The average venom yield per bite is 100 to 150 mg (Minton, 1974).^[5] The mortality rate for untreated bites is not exactly known, but 20-50% is considered to be the general range based on medical literature dating back to the 1950's to the present. It is reported that most untreated bites don't result in death and this can be due to various factors including the amount of venom injected, psychological state of the bitten subject, the penetration of one or both fangs, and so on. Mechanical ventilation and symptom management is often enough to save a victim's life, but serious Cape cobra envenomation cases will require antivenom.^[3] When death does occur, it normally takes up to five hours, but deaths have been recorded at two hours after being bitten and it's often as a result of respiratory failure because of the onset of paralysis.^[5][3]

References

1. ^ ^{a b c d e f g h i} Phelps, T. (2007). Observations of the Cape cobra, Naja nivea (Serpentes: Elapidae) in the DeHoop Nature Reserve, Western Cape Province, South Africa. Herpetological Bulletin 99: 29-35.
2. ^ ^{a b c d e f} Cape Cobra (Naja nivea) Info
3. ^ ^{a b c d e f g h i} Zug, George R. (1996). Snakes in Question: The Smithsonian Answer Book. Washington D.C., USA: Smithsonian Institution Scholarly Press. ISBN 1560986484. 
4. ^ Phelps, T. (2006). Elapidae. Naja nivea. Scavenging. African Herp News. 40: 24
5. ^ ^{a b c} University of Adelaide-Clinical Toxinology Resources
6. ^ LD50 Menu (Dr. Bryan Grieg Fry)