Reptiles & Amphibians of France - Seoane's viper, Vipera seoanei

Seoane's viper, Vipera seoanei
Lataste, 1879

History and origin
The Seoanei's viper was first described by Lataste in 1879, the scientific name of this species is Vipera seoanei, Vipera meaning viper and seoanei, this name comes from a certain Mr Victor Lopez Seoane, Lataste named this species after him.

Characteristics
They are characterised from other vipers by their yellowish tail tip.

Description
=Size=
They are born at around 15 cm, growing up to sometimes 65 cm.
=Morphology=
They are short and relatively elegant, sometimes being robust looking (especially females), a noticeable slim short tail for females, males having a longer tail. Their head is less heavily built than that of some other viper species like Asp Viper. They have keeled scales and vertical pupils.
=Patterns & colours=
Highly variable. They are brown, gray or olive in colour, with a darker zigzag pattern on the back and various darker markings on the flanks. The so-called bilineata form has no obvious zigzag but a brownish or reddish wide band running down the back, bordered by more narrow light creamy coloured lines. Their bellies are blackish with lighter spots. Black individuals are not particularly rare. This species is characterised from other vipers by their yellowish tail tip.

Geographical range
Found only along the northern Spanish coast, the extreme north (western) parts of Portugal and in a very restricted area of SW France.

Subspecies
- cantabrica - Found in northwestern Spain, in the Cantabria mountains to north of Léon. May look like Vipera aspis zinnikeri.
- seoanei - Found elsewhere in the species’ range.

Sexual differences
Females and larger then the males, especially in late spring when they carry the young.

Seasonal variations
None.

Diet
They eat mainly small mammals but also lizards and other reptiles and birds. Juveniles prefer to feed on lizards.

Defensive habits
They prefer to escape but if cornered of caught they will hiss very loudly and for long periods, and rapidly sticking with their mouth open. The temperament depends on individual specimens... When they bite, they usually don’t put their fangs to use and they give what is known as a ‘dry bite’ where no venom is injected, we must remember that this snake as like other venomous snakes have not got the capability to envenomate us to harm us but to kill their prey in order to survive.

Reproduction
Breeding occurs when the snakes wake up from hibernation in spring, a week after, they are all looking for each other and mating begins. The female carries around with her about 7 young (extremes of 2 to 12). They are born 2 to 3 months after being conceived. In northern parts of its range where a cool summer may occur, the young are born the following year. Females breed once every two years.

Sexual maturity, life span
The average life span for Vipera seoanei is about 13 years, they reach their sexual maturity in their third year for males and in the fifth for females.

Habits
Mainly diurnal. When they are disturbed, they may stay quite calm and move away quite slowly. They are slow and docile, until trapped or cornered when they become very defensive biting rapidly. Best seen at relatively low temperatures, when they are basking to gain body heat. Optimal body temperature between 24 and 28 C. Air humidity seems an important factor for observation when the air is too dry they don't expose themselves to sunshine, but stay in the vegetation. Hibernation from mid October till mid March in dryer places underground. Mice and rabbit holes are often used for hibernation. Also holes under trees are used for this purpose. As soon as soil temperature rises above 10 C, they come out and expose themselves to sunshine.

Venom
The strength of the venom depends on the subspecies, with ssp. cantabrica having the more potent poison. Symptoms in humans are pain, fever, nausea, swelling, etc. but rarely death.

Habitat
They live in open woodland, grasslands and damp meadows, mostly in relatively cool and not too dry places. As they prefer basking in sunshine at low temperatures, they avoid excessive heat or dryness. One of the most common snake species within its range.

Predators
Birds of prey and mammals.