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Bitis gabonicaGaboon Adder

By Jacqueline Howard

Geographic Range

Gaboon vipers are found throughout sub-Saharan Africa. (FitzSimons, 1970; Isemonger, 1962)

Habitat

Gaboon vipers are abundant in rainforests and other moist, tropical habitats. They tend to take shelter in the leaf litter of forest floors. (FitzSimons, 1970; Isemonger, 1962)

Physical Description

Gaboon vipers are large snakes, the largest of the vipers, with an average adult length of about 1.2 meters. However, some have been recorded as large as 2.2 m long or greater. They can weigh up 10 kg with a head about 12.7 cm wide and fangs about 5 cm long. Gaboon vipers have triangular heads with prominent rostral horns. There is also a very dark line down the center of the head and two dark spots above each side of the jaw. The scales are ridged and keeled on the majority of the body, however there are a few rows of scales on the lowest part of both sides that are smooth. There are 28 to 40 rows of scales in the middle part of the body, an average of 125 to 140 rows on the ventral side. Males and females differ in the number of scales they have (females having less than 135 rows and males having less than 132 rows). Color patterns of gaboon vipers are truly stunning, forming a symmetrical design that makes a unique pattern on the scales. The base color is typically a brown or purple color. On top of that are yellow, quadrangular shapes, that are aligned neatly over the center of the back. These shapes have hourglass brown spaces, and along the sides of the body are triangular patterns, which are the brown or purple coloring and in between the series of triangles are yellow and purple stains. The ventral side is a light yellow color with dark spots sprinkled throughout. This camouflage pattern is adaptive in helping gaboon vipers blend into their surroundings. Their eyes are grayish with a hint of silver. (Cansdale, 1961; FitzSimons, 1970; Isemonger, 1962; Krutein, US Copyright Law and the Berne Convention 1979)

  • Sexual Dimorphism
  • female larger
  • Range mass
    7 to 10 kg
    15.42 to 22.03 lb
  • Range length
    2.2 (high) m
    7.22 (high) ft
  • Average length
    1.2 m
    3.94 ft

Development

Gaboon vipers are viviparous, with a 7 month gestation period. They give birth to about 30 or more offspring at once. (FitzSimons, 1970)

Reproduction

Observations of gaboon vipers kept in captivity have lead to some information about their mating systems. Gaboon vipers generally mate in the rainy season, so spraying water on the vipers in captivity helps to mimic the rainy season. The female will then get restless and lift her tail, showing the male that she is ready to mate. They may sway back and forth as well. (Dexter, VenomousReptiles.org 2000 - 2005 )

Gaboon vipers mate during the rainy season in Africa, which is between September and December. The gaboon viper is viviparous, with a 7 month gestation period, and gives birth to about 30 or 40 offspring at once. (Dexter, VenomousReptiles.org 2000 - 2005 ; Dexter, VenomousReptiles.org 2000 - 2005 ; Fitch, 1970)

  • Breeding season
    September - December
  • Range number of offspring
    20 to 50
  • Average gestation period
    7 months

When the offspring are born, they are already as big as 30 cm long and already have adult-looking patterns on their scales. There is no real parental care once the offspring are born. (FitzSimons, 1970)

  • Parental Investment
  • no parental involvement
  • pre-fertilization
    • provisioning
    • protecting
      • female

Lifespan/Longevity

There is no information on the longevity of gaboon vipers.

  • Average lifespan
    Status: captivity
    18 years
    AnAge

Behavior

Gaboon vipers are nocturnal and solitary. They are most active around sunset, when they emerge from a dark hiding place in search of prey. They generally lie perfectly still, blending in with the leaves of the forest floor, waiting for prey to cross their path. (Isemonger, 1962; Krutein, US Copyright Law and the Berne Convention 1979)

Communication and Perception

Gaboon vipers, like other vipers, detect vibrations, chemical signals, and visual cues. Using all to detect and attack prey. There is nothing known about how gaboon vipers communicate, but they may use chemical cues to to locate receptive mates.

Food Habits

Gaboon vipers await their prey from a hiding spot and quickly attack with 5 cm fangs, injecting toxic venom into the tissues of the prey. They eat primarily small mammals, such as rodents, ground-living or feeding birds (such as francolins or doves), and frogs and toads. Specimens of gaboon vipers have been found to have ingested giant rats (Cricetomys gambianus), brush-tailed porcupines (Atherurus africanus), and fully grown royal antelopes (Neotragus pygmaeus). (Cansdale, 1961; FitzSimons, 1970; Isemonger, 1962)

  • Primary Diet
  • carnivore
    • eats terrestrial vertebrates
  • Animal Foods
  • birds
  • mammals
  • amphibians
  • reptiles

Predation

There are no known predators of gaboon vipers. They are cryptically colored, blending in well with leaf litter on the forest floor, perhaps to hide from potential prey.

  • Anti-predator Adaptations
  • cryptic

Ecosystem Roles

As a predator of small mammals, gaboon vipers help to control rodent populations. (Kayembe, WhoZoo Project 1998-2005)

Economic Importance for Humans: Positive

Gaboon viper venom is not known to have any medical uses, but further research is necessary.

Economic Importance for Humans: Negative

Gaboon vipers can directly harm humans if disturbed but they are not generally aggressive if left alone. When disturbed, gaboon vipers will either sound a loud hiss or deliver a venomous bite. Many humans have died from gaboon viper bites. Survivors have often had to have affected limbs amputated. Their deadly venom contains neurotoxin and hemotoxin, which destroys the blood cells and vessels. (Isemonger, 1962; Kayembe, WhoZoo Project 1998-2005)

  • Negative Impacts
  • injures humans

Conservation Status

Gaboon vipers are not currently considered threatened. (Kayembe, WhoZoo Project 1998-2005)

Contributors

Tanya Dewey (editor), Animal Diversity Web.

Jacqueline Howard (author), Kalamazoo College, Ann Fraser (editor, instructor), Kalamazoo College.

Glossary

Ethiopian

living in sub-Saharan Africa (south of 30 degrees north) and Madagascar.

World Map

carnivore

an animal that mainly eats meat

chemical

uses smells or other chemicals to communicate

cryptic

having markings, coloration, shapes, or other features that cause an animal to be camouflaged in its natural environment; being difficult to see or otherwise detect.

native range

the area in which the animal is naturally found, the region in which it is endemic.

nocturnal

active during the night

rainforest

rainforests, both temperate and tropical, are dominated by trees often forming a closed canopy with little light reaching the ground. Epiphytes and climbing plants are also abundant. Precipitation is typically not limiting, but may be somewhat seasonal.

sedentary

remains in the same area

solitary

lives alone

terrestrial

Living on the ground.

tropical

the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.

venomous

an animal which has an organ capable of injecting a poisonous substance into a wound (for example, scorpions, jellyfish, and rattlesnakes).

vibrations

movements of a hard surface that are produced by animals as signals to others

visual

uses sight to communicate

viviparous

reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.

References

Cansdale, G. 1961. West African Snakes. Hong Kong: Hong Kong, Sheck Wah Tong Press.

Dexter, B. VenomousReptiles.org 2000 - 2005 . "Venomous Reptiles" (On-line). Accessed November 23, 2005 at http://www.venomousreptiles.org/articles/93.

Fitch, H. 1970. Reproductive Cycles of Lizards and Snakes. Lawrence, Kansas: The University of Kansas Printing Service.

FitzSimons, V. 1970. A Field Guide to the Snakes of Africa. Great Brittain: Great Brittain Collins Clear-Type Press.

Isemonger, R. 1962. Snakes of Africa: Southern, Central, and East. Cape Town: Cape Town, Cape and Transversaal Printers.

Kayembe, K. WhoZoo Project 1998-2005. "WhoZoo" (On-line). Accessed October 24, 2005 at http://www.whozoo.org/Intro2002/KayKayembe/KTK_gaboonviper.html.

Krutein, W. US Copyright Law and the Berne Convention 1979. "Photovault" (On-line).

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