Atheris broadleyi uses primarily vision for communication and perception, but also makes use of tactile and olfactory senses. When threatened, it extends its body and raises the anterior portion of its body into the air, settling into a striking position. Posturing is used to ward of predators and during intrasexual competition for mates. During male-male competition, the individual that makes himself appear larger is most often dominant. Communication between sexes is done primarily for reproduction. In order to attract potential mates, males perform a number of different motions, including tail waving, rubbing, biting, and rhythmic body motions. Atheris broadleyi lacks the heat-sensing pit organs present in many other viper species. Instead, they rely on visual, tactile, and olfactory senses to detect and capture prey.
Communication Channels: visual ; tactile ; chemical
Perception Channels: visual ; tactile ; acoustic ; chemical
Atheris broadleyi has not been evaluated by the IUCN and is not listed as a species of concern on any known threatened species lists.
US Federal List: no special status
CITES: no special status
State of Michigan List: no special status
After fertilization, Atheris broadleyi gives birth to live young (ovoviviparous). Growth is indeterminate, but slows as the snake matures. Juveniles are born venomous and are responsible for capturing their own food. Young snakes can be recognized by the unique coloration of their scales. In addition, the end of their tail is distinctly different and is used as a lure to attract small prey. Time to maturity has not been documented. As individuals age, the coloration of their scales becomes more uniform and may change completely in some cases.
Development - Life Cycle: indeterminate growth
Green bush vipers are venomous, and as such pose a potential threat to humans. Many unprovoked attacks occur during agricultural activities, as this species is an ambush predator and lies in wait for potential prey.
Negative Impacts: injures humans (bites or stings, venomous )
Many vipers, including Atheris broadleyi are farmed for their venom, a process is known as "milking". The venom is used to produce antivenom and for medical and biological uses. Although it is not hunted as a primary food source, it is occasionally captured in fishing nets as by-catch and thus sometimes used as food source.
Positive Impacts: food ; body parts are source of valuable material; source of medicine or drug ; research and education
Because it feeds primarily on small rodents, many of which may carry zoonotic diseases and be considered agricultural pests, Atheris broadleyi may help control pest species throughout its geographic range. Parasites of this species have not been documented.
Atheris broadleyi is carnivorous. It does most of its hunting at night and is an ambush predator. It feeds mainly on small, nocturnal mammals such as shrews and rodents. Less commonly, it feeds on birds and small reptiles. Juveniles feed on reptiles more often than their adult counterparts. Like other vipers, A. squamigera adults often prey on adolescent snakes of their own species. The venom of A. squamigera is lethal and is used to subdue and kill prey prior to ingestion. In humans, the bite of A. squamigera often causes fever, hemorrhaging, and death.
Animal Foods: birds; mammals; reptiles
Primary Diet: carnivore (Eats terrestrial vertebrates)
Atheris broadleyi (green bush viper) inhabits arts of western and central Africa. Its geographic range extends into Kamanyola, a province of Kivu, Congo and Takamanda Forest Reserve in Cameroon. Atheris broadleyi has been recorded in the lower elevation forests of Cameroon, particularly those with dense vegetation.
Biogeographic Regions: ethiopian (Native )
Atheris broadleyi occurs primarily in tropical forests and areas with dense vegetation where small rodents and other prey animals are abundant. This species is most commonly found at elevations ranging from 100 to 400 m in elevation. The climate of the Takamanda Forest Reserve, Cameroon, where this species is particularly abundant, alternates between rainy (April to November) and dry seasons. Rainfall in the Reserve varies from 1500 mm to 10,000 mm per year. In other forest habitats, such as the Guinean Forest in West Africa, A. squamigera occurs most often at lower elevations, which tends to support greater vegetation densities. In general, A. squamigera resides in moist, terrestrial, and arboreal habitats throughout its geographic range.
Range elevation: 100 to 400 m.
Habitat Regions: tropical ; terrestrial
Terrestrial Biomes: forest ; rainforest
Average lifespan for green bush vipers has not been documented. Most vipers live 10 to 20 years in the wild. It has been suggested that captive vipers may live longer because risk factors such as predation, disease, and diet are controlled.
Atheris broadleyi has a compressed body, with scales that are strongly keeled. The dorsal surface of the head is covered with small keeled scales, one of its most distinct features. Typical coloration for is yellowish-green on the dorsum and venter, helping to camouflage it in its natural habitat. Females tend to be slightly larger than males, reaching an average length of 71.2 cm. The average recorded size for males is 65.7 cm. The head is typically larger than their neck, and is triangular. Nasal orientation is lateral, and the openings are partly divided. The snout has a roundish tip and is reltively short. Compared with most other snake species, A. squamigera also has relatively large eyes. It has long, tubular, hollow fangs, which are supplied with venom by a gland located on the upper jaw, between the eyes and mouth. These retractable fangs are connected to a bone that can shift posteriorly within the upper jaw to house the fangs.
Range length: 50 to 79.9 cm.
Average length: 65 to 70 cm.
Other Physical Features: heterothermic ; venomous
Sexual Dimorphism: female larger
Atheris broadleyi has few predators. The most commonly noted predators are other snakes, including conspecifics. Humans living near A. squamigera habitat sometime capture it for food, but typically only when it threatens fishing or agricultural activities.
To avoid predation, green bush vipers rely on the same mechanisms used for hunting. Their camouflaged scale patterns allow them to blend in with the surrounding environment. This coloration serves a two-fold purpose, allowing the viper to strike and surprise potential prey, and go unnoticed by potential predators. This ambush-based hiding and hunting behavior allows the snake to sometimes hide rather than engaging in defensive or aggressive behavior. The bright coloration also serves as a warning of the snake's venomous nature to potentially threatening animals.
Known Predators:
Anti-predator Adaptations: aposematic ; cryptic
Although the specific mating system of Atheris broadleyi is currently unknown, vipers are typically seasonally monogamous. During courtship, male and female vipers face one another, followed by head and body gestures, which allow for mounting. For example, males often approach their mate while swaying their head side to side in order to engage a female.
Atheris broadleyi reproduces once yearly, typically during the wet season (May to August). Mating occurs most often at night cycle, between 6 pm to 2 am. Once the eggs are fertilized, gestation lasts for 2 months. On average, 7 to 9 offspring are produced. Females reach reproductive maturity 42 months after birth. Males are capable of reproduction much earlier, typically after 24 months.
Breeding interval: Atheris broadleyi breeds once yearly.
Breeding season: Atheris broadleyi breeds during the wet season, from May to August).
Range number of offspring: 2 to 19.
Average number of offspring: 7 to 9.
Average gestation period: 2 months.
Average age at sexual or reproductive maturity (female): 42 months.
Average age at sexual or reproductive maturity (male): 24 months.
Key Reproductive Features: iteroparous ; seasonal breeding ; sexual ; fertilization ; ovoviviparous
As an ovoviviparous species, female green bush vipers carry their unborn young internally, protecting them in the pre-birth stage. Like many vipers, green bush vipers abandon offspring immediately after birth. Neonates are venomous and completely independent.
Parental Investment: pre-hatching/birth (Protecting: Female)
Atheris squamigera (common names: green bush viper,[2][3] variable bush viper,[4][5] leaf viper,[5] Hallowell's green tree viper,[6] and others) is a venomous viper species endemic to west and central Africa. No subspecies are currently recognized.[7]
Atheris squamigera grows to an average total length (body + tail) of 46 to 60 cm (about 18 to 24 inches), with a maximum total length that sometimes exceeds 78 cm (about 31 inches). Females are usually larger than males.[2]
The head is broad and flat, distinct from the neck. The mouth has a very large gape. The head is thickly covered with keeled, imbricate scales. The rostral scale is not visible from above. A very small scale just above the rostral is flanked by very large scales on either side. The nostrils are lateral. The eye and the nasal are separated by 2 scales. Across the top of the head, there are 7 to 9 interorbital scales. There are 10 to 18 circumorbital scales. There are 2 (rarely 1 or more than 2) rows of scales that separate the eyes from the labials. There are 9 to 12 supralabials and 9 to 12 sublabials. Of the latter, the anterior 2 or 3 touch the chin shields, of which there is only one small pair. The gular scales are keeled.[2]
Midbody there are 15 to 23 rows of dorsal scales, 11 to 17 posteriorly. There are 152 to 175 ventral scales and 45 to 67 undivided subcaudals. It is possible that there is a variation in morphometric characters related to habitat:[2]
The coloration is the same in some populations, but variable in others. The dorsal color varies from sage green or light green to green, dark green, bluish, olive or dark olive brown. Rare specimens may be found that are yellow, reddish or slate gray. The scales have light-colored keels and sometimes yellow tips that form a series of 30 or more light crossbands or chevrons. On the tail, there are 10 to 19 chevrons: not always clearly defined, but usually present. The ventral edge of the dorsum has light spots in pairs. An interstitial black color is visible only when the skin is stretched. The belly is yellow or dull to pale olive; it may be uniform in color, or heavily mottled with blackish spots. The throat is sometimes yellow. The tail has a conspicuous ivory white tip, 7 to 12 mm long, extending back over 10 subcaudals.[2]
Neonates have a dark, olive coloration with wavy bars, paler olive or yellowish olive with fine dark olive margins, bars at 5 mm (0.20 in) intervals, and a belly that is paler greenish olive. The adult color pattern develops within 3 to 4 months.[2]
In the wild A. squamigeras begin reproducing once they reach sexual maturity at 42 months for females, and at 24 months for males respectively. Reproduction takes place once annually, most often during the wet season. A. squamigera is viviparous, and a single successful pairing can produce up to 19 neonates, although the average is 7–9. The female A. squamigera carries her young internally during a gestation period of two months. Following birth, the neonates are abandoned by the mother as they are born venomous and entirely self sufficient.[8]
The diet of Atheris squamigera consists primarily of small mammals, although cases of cannibalism within the species have been documented.[9]
A. squamigera is a nocturnal hunter and its coloring allows it to blend in with its environment and ambush the small prey it feeds on. It is equipped with two front hollow fangs through which it injects its prey with hemotoxic venom rendering it defenseless.[10]
Common names for A. squamigera include green bush viper,[2][3] variable bush viper,[4][5] leaf viper, common bush viper,[5] bush viper,[11] and tree viper,[12] Hallowell's green tree viper.[6]
Atheris squamigera is found in the forest habitats of West and central Africa: from Ghana eastward to western Kenya and Tanzania, south to northern Angola and Bioko Island.
The type locality is given as "Near the river Gaboon, Guinea" [Gabon].[1]
Atheris squamigera is the most well distributed species of the Atheris genus. Scientists believe that the current pattern of dispersal is of the Atheris species, including that of the A. squamigera may have been influenced by a combination of past climatic events, geological activities, the shifting of tectonic plates over millions of years, as well as stochastic dispersal.[13]
Atheris squamigera inhabits mostly rainforest, preferring relatively low and thick flowering bushes.[3]
Atheris squamigera requires a very high level of humidity to breed. In one case, males and females were kept separate from January to the end of November. Two females became gravid (with one observed mating). Each produced eight young: a smaller percentage were yellow (possible recessive gene), most being green. In each brood, there was also one nonviable green specimen. Some of the neonates fed readily on frogs, while the others had to be force-fed pinkie mice. All fed independently after a few months.[2]
Bites from A. squamigera have resulted in at least one report of severe hematological complications[14] as well as two deaths. Although no specific antivenom is made for the genus Atheris, antivenom for the genus Echis has been shown to be partially effective in neutralizing Atheris venom.[15]
A number of subspecies of A. squamigera may be encountered in literature. These include:[1][2][3]
Furthermore, specimens from Dimonika and Menengue in Congo are sometimes treated as a separate species: A. laeviceps. It has been distinguished as having a group of small scales on top of the head, a row of scales that separates the suboculars and the upper labials, as well as a yellow coloration.[3]
{{cite journal}}: CS1 maint: multiple names: authors list (link) {{cite journal}}: CS1 maint: multiple names: authors list (link) Atheris squamigera (common names: green bush viper, variable bush viper, leaf viper, Hallowell's green tree viper, and ) is a venomous viper species endemic to west and central Africa. No subspecies are currently recognized.
