North Iberian adder
| North Iberian adder | ||||||||||||
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North Iberian adder ( Vipera seoanei ) in the Pyrenees near the border between France and Spain |
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| Vipera seoanei | ||||||||||||
| Lataste , 1879 |
The Spanish or Vipera Seoanei ( Vipera seoanei ), also known as Seoane Viper or Iberienotter is a small to medium sized venomous snake from the family of Vipers (Viperidae), which only in the extreme north of the Iberian Peninsula occurs. When it was first described it was regarded as a subspecies of the adder ( V. berus ), but is now a recognized species .
features
measurements and weight
The North Iberian adder reaches a total length of 45 to 55 cm on average, the maximum length is 60 to probably about 75 cm. The longest individuals so far were a 12 to 13 year old male with 58.5 cm as well as a 66 cm long female from Asturias and a 59 cm long male from Galicia . In contrast, no snakes longer than 50 cm are known from Portugal. The tail is relatively short and takes up about 10 to 15% of the total length. As with most species of vipers, the physique is strong, although this species is somewhat slimmer than the aspis viper ( V. aspis ). The average weight is around 90 grams, pregnant females become significantly heavier. A clear sexual dimorphism is not developed in the species, only the tail is significantly longer in the males with about 13.8% of the head-trunk length compared to about 11.3% in the females. Correspondingly, males have six to seven additional caudal vertebrae.
coloring
The basic color varies from light beige to chestnut brown. A wavy band, which is also typical of the adder ( V. berus ) , usually extends over the back from head to tail . Parallel to this, there is a series of smaller dark spots on each of the flanks. There are two to three dark transverse bands on the head and a dark V-mark on the neck. Often a dark bandage extends from the eyes to the neck. The species is very variable in its coloration and in addition to this normal coloration, individuals with longitudinal stripes or completely brown to black animals can also occur. According to this range of variation, a distinction is made between four color patterns:
- the classic or typical color pattern with a light gray to beige basic color and a longitudinal band of alternating spots on the back, which can be fused to form a zigzag band.
- the bilineata pattern, mostly dark in color, and two dorsolateral longitudinal ligaments as a drawing on the back.
- the cantabrica pattern with a mostly gray basic color and a narrow zigzag pattern or two weak longitudinal bands as a drawing on the back.
- the uniform color pattern without back markings and a gray basic color. Completely black ( melanism ) or brown animals are also classified in this pattern . About 31% of the highland snakes of the Cantabrian Mountains and even up to 85% of the animals living in Portugal are melanistic.
Scaling
The body scales have a distinct keel, which has fine longitudinal lines in its ultrastructure , which are covered by curved transverse lines. Around the middle of the body the snake has 21 rows of dorsal scales, in very rare cases only 19. The ventral side is monochrome dark gray to black and shows 129 to 150 ventralia , which are joined by an undivided anal shield and 32 to 42 subcaudalia .
The head, which is clearly set off from the body, has a triangular, rounded shape, the muzzle is slightly bent up at the front. The head is usually covered with many small and keeled scales, but there may also be a large forehead shield ( frontal ) and crown shield ( parietal ). The pupil of the large eyes is slit vertically and the iris is lighter in color in the upper area. Between the edge of the eye and the shields of the upper lip there is a series of under-eye shields ( subocularia ), often another series of scales is placed around the eye. As a rule, the snake has nine, less often eight or ten upper lip shields ( supralabials ).
Karyotype
The karyotype of the North Iberian adder, with 18 pairs of chromosomes (2n = 36), 8 of which are very large ( macrochromosomes ), corresponds to that of most of the viper species examined. The only exceptions to this are the aspis viper and the European horned viper ( V. ammodytes ) with 21 chromosome pairs (2n = 42) and 11 macrochromosome sets. Despite the different chromosome sets, hybrids between the North Iberian adder and the aspic viper can occur in captivity. These have a total of 39 chromosomes, which are the normal 18 chromosome pairs and an additional three unpaired chromosomes of the asp viper.
distribution and habitat
Geographical distribution
The distribution area of the North Iberian adder is limited to the northern Iberian Peninsula and extends from the extreme southwest of France in the French-Spanish border area in the Pyrenees over the Spanish Basque Country and northern Spain to the extreme north of Portugal in the area of the Minho in the Viana do Castelo district . The Spanish distribution area includes almost all of Galicia and the northern areas of the provinces of Cantabria , Léon , Palencia , Burgos , Álava and Navarra as well as the extreme west of the province of Zamora . In Portugal, only three populations are known in Paredes de Coura , Castro Laboreiro and Soajo, and Tourém , Montalegre and Larouco .
It is regionally different at altitudes up to 1200 m above sea level in Portugal and up to a maximum of 1900 m in the coastal mountains of Cantabria . In Portugal and the neighboring Spanish areas of distribution, the snakes are only found in higher mountain locations, which is attributed to the management and the associated destruction of the original vegetation of the lowlands in addition to the climatic factors.
The subspecies V. s. cantabria only occurs in the high altitudes of Cantabria, the nominate form V. s. seoanei in the entire rest of the distribution area. It is the only type of vipers in large parts of its range. In the upper Ebro Valley in northern Burgos and in the Basque Country, the distribution areas of the North Iberian adder slightly overlap with those of the aspis viper ( V. aspis ) and in northern Portugal with those of the inverted-nosed viper ( V. latastei ). However, these overlaps are only geographical - the habitat requirements for humidity and temperature of the three species differ so greatly that they can never be found together in the same habitat . The adder, on the other hand, does not occur in the distribution area of the North Iberian adder, its southernmost occurrence is in France in the area of the Lozère department .
habitat
As a habitat, the snake prefers warm and humid habitats with high levels of precipitation. Climatically, the habitat of the North Iberian adder is characterized by Atlantic and subtropical influences, which result in very mild winters and relatively warm summers without dry seasons. Rainfall is very high throughout the year. Winter temperatures are significantly lower than in the lowlands, especially at higher altitudes. The animals avoid dry areas within their range, such as those found in large parts of Léon .
The soil of the habitats is usually stony and has abundant ground vegetation, and moist habitats such as river banks or wet meadows are preferred. Open deciduous forests with pedunculate oak or Pyrenean oak stocks ( Quercus robur and Q. pyrenaica ) and the edges of forests and meadows are typical habitats of this species. This snake is more than other vipers bound to dense undergrowth and lives mainly in stocks of bracken , Gorse and heather . The habitats must offer opportunities for sunbathing, accordingly, especially in mountain locations, almost exclusively southern slopes are populated. In contrast to other viper species, rocky areas are rarely used.
Way of life
Activity and social behavior
The North Iberian adder is mainly active during the day and at dusk, depending on the temperatures. In summer in particular, activity is highest in the morning and evening, while there is an inactive phase in the middle of the day. On particularly hot days with temperatures above 30 ° C, the activity can also be completely shifted into the night. The required temperatures start at over 12 ° C, while the optimal body temperature is around 30 ° C. The snakes reach these by extensive sunbathing in exposed areas. During the sun, many individuals can be observed together, lying next to each other and sometimes even on top of each other in suitable places.
During the winter months, the species hibernates, which lasts three to four months from the end of October to March, depending on the temperatures and thus often also on the altitude. Activity during this hibernation is very rare. Adult males are found earlier than females after overwintering. Like most snakes, North Iberian adders are solitary animals, so social contacts are limited to chance encounters and shared use of the sun-exposed places. During the mating seasons from March to April, the encounters increase, with sexual contacts and comment fights between the males.
nutrition
Like most other vipers, the North Iberian adder is a prey hunter and does not specialize in certain prey. It primarily hunts mice and other small mammals , lizards and frogs , which it kills with a poison bite and then swallowed completely. Since newborn small mammals or nesting birds have also been found in the stomach of the snake, it will occasionally actively rummage in its search for food. Adult adders eat an average of three to seven prey a year. The highest prey frequency with up to 13 prey per year was determined for non-reproductive females, followed by adult males and juvenile snakes. Reproductive females, on the other hand, eat much less frequently and only prey on around three to six prey a year. Fasting periods exist in males during the mating season and in females during pregnancy.
The proportion of different prey animals could be determined on the basis of stomach examinations of animals from Galicia and Cantabria. Accordingly, the majority of the diet consists of rodents , especially voles (genera Microtus and Pitymys ) with a proportion of 30 to over 40% and wood mice with around 10%. Shrews follow with regionally between 4 and 15%. Lizards as the Iberian rock lizard ( Iberolacerta monticola ), the Waldeidechse ( Zootoca vivipara ) and lizards (genus Podarcis ) and the slow worm ( Anguis fragilis ) vary proportionately between three and five percent, Caudates as the salamander ( Salam salamandra ) and the gold stripes Salamanders ( Chioglossa lusitanica ) are also around 3%, real frogs (genus Rana ) around 6%. Birds could only be found in individuals from Cantabria and represent about 5% of the prey here. The dominance of mammals in the food spectrum becomes even clearer via the biomass comparison: around 90% of the total mass was made up of small mammals, only around 10% of all other prey animals.
Young snakes feed mainly on small lizards and frogs that have recently been metamorphosed . After about two years and with a body length of 35 to 40 centimeters, they then also prey on the first shrews and other small mammals.
Reproduction and development
The mating takes place after the hibernation in spring from the end of March to the beginning of May, the spring moulting of the males takes place, unlike in the adder and other species of the subgenus Pelias, only after mating. During the mating season, comment fights between the competing males take place, with the opponents straightening their front bodies and trying to push the opponent to the ground. However, since these fights take place with every encounter between males and mostly in the absence of the females, the chance of mating is not reduced for the inferior male either. Before the actual mating, the male sometimes strokes his head over the female's body for hours and then lies down on the same. Then it tries to grip the tail with its own and to place the cloacas on top of each other. With the introduction of one of the paired hemipenes , copulation begins, which can last up to two hours. The ovulation of the females and thus the fertilization of the egg cells does not begin until after the final phase of the mating season in May to June.
The young snakes are born about three months after fertilization. The females give birth to two to ten live young animals, so they are ovoviviparous , with larger females usually having more young. On average, the newborn snakes are about 15 to 18 centimeters long and weigh 4.4 to 6.0 grams, the entire litter thus weighs on average about 35 grams, which is half the body weight of an average female. As a rule, the female adders give birth to new offspring about every two years (biannual reproductive cycle), with the proportion of biannual females increasing with geographical latitude and altitude due to the lower temperatures.
The young snakes grow comparatively quickly. After four or five years they will have reached a total length of 32 to 38 centimeters. During this time, the snakes become sexually mature, which also reduces the growth rate. After eight years the animals are on average about 42 centimeters, after ten years 44 centimeters long; the maximum life expectancy is assumed to be around 13 years.
Predators
A number of birds of prey and predators within their range come into question as predators of the North Iberian adder . As the main predator can hereby Domestic be considered also remains were the queue in faecal samples of the red fox ( Vulpes vulpes detected). The common buzzard ( Buteo buteo ) and, for Galicia, the otter ( Lutra lutra ) and the European genet ( Genetta genetta ) have also been identified as predators .
Systematics
The North Iberian adder was first described by Fernand Lataste as a subspecies of the adder ( Vipera berus seoanei ). Lataste honored the Spanish naturalist Victor López Seoane (1832–1900) with the scientific name. As a separate species Pelia seoanei , the North Iberian adder was first described by Reuss in 1927. The classification in species rank, but within the genus Vipera (= V. seoanei ), was confirmed in 1976 by Hubert Saint Girons and Raymond Duguy. The demarcation from the adder is mainly through the scaling ( pholidosis ), in particular through the signs on the top of the head. In the North Iberian adder, the shields on the top of the head, which are largely dissolved, are almost completely present. Another striking difference that differentiates the North Iberian adder from all closely related species is the late moulting of the males, which only occurs after mating. Differences at the molecular level as well as in the poison composition justify the species distinction.
In 1983, Franzisco Braña and Santago Bas described the two now recognized subspecies V. s. seoanei and V. s. cantabrica .
The North Iberian adder is systematically classified in the genus Vipera and there often together with the adder ( V. berus ) and some other species in the subgenus Pelias . Accordingly, there is no closer relationship with the aspis viper ( V. aspis ), although mixed breeds of both species have been documented. A comparison of the mitochondrial DNA in 2000 confirmed the close relationship to the adder. Here both species are sister species, the closest relatives were, according to the analysis, Dinnik's Caucasian otter ( V. dinniki ) and the European horned otter ( V. ammodytes ). However, the analysis did not include all species of the genus Vipera , so that no phylogenetic conclusions can be drawn for the entire genus. Svetlana Kalyabina et al. 2002 presented a relationship analysis based on mitochondrial DNA, according to which the adder forms a monophyletic group together with the forest steppe otter ( V. nikolskii ) and Baran's viper ( V. barani ), whose sister species is the North Iberian adder.
Snake venom
The venom of the North Iberian adder is similar in effect and composition to the venom of the asp viper, but is considered to be less effective than this and that of the adder. Although the composition of the poison varies only slightly between the different populations, the differences in toxicity are relatively large. For example, snakes in the Basque Country and in the coastal areas of Cantabria are classified as slightly toxic with a lethal dose LD 50 in rats with a live weight of around 20 grams of 23.1 to 23.6 mg snake venom, while in populations of the subspecies V. s. cantabrica in the Cantabrian highlands, 6.9 to 9.9 mg of the poison have already been determined as an LD 50 value. In the other areas, the poisonous effect is to be assumed between these two extremes.
As with other European vipers, the symptoms of the bite are extensive swelling around the bite site and the neurotoxins contained in it can lead to shortness of breath and heart problems. The majority of the viper venom has a hemotoxic effect, i.e. it primarily destroys cells of the blood and the tissues surrounding them with various proteases . This leads to bluish discolouration in the area of the swelling due to the leakage of blood into the connective tissue. Treatment in hospital with an antiserum that acts unspecifically in all European viper species is usually appropriate.
There is hardly any information on the frequency of bite injuries caused by this species. Between 1965 and 1980, only 23 poisonings by the North Iberian adder were reported; more recent figures are unknown.
Hazard and protection
Despite its limited range, the North Iberian adder is rated by the World Conservation Union ( IUCN ) as “ Least Concern ” . This assessment corresponds to the classification in Spain, where the snake is considered safe. In Portugal, however, the North Iberian adder is considered to be threatened due to its very small and fragmented distribution and the continued decline in habitat. In southern France, the distribution is also limited to isolated populations and the snake has been locally exterminated there due to habitat destruction in the course of urbanization.
Information on population developments of the species is not known; however, there is no sharp decrease, indicating a greater risk. Roads, where the animals are run over relatively frequently, as well as the increasing destruction of suitable habitats through intensive agriculture and destruction of forest edges and retreats are to be assumed as the main sources of danger. Large-scale planting of non-native woods such as eucalyptus and pine forests and slash- and-burn operations are also given as causes of danger.
Legal protection status (selection)
- Fauna-Flora-Habitat Directive (FFH-RL): Annex IV (species to be strictly protected; Spanish occurrences are excluded)
- Federal Nature Conservation Act (BNatSchG): strictly protected
Like all European snake species, it is listed in Appendix II of the Bern Convention ( Convention on the Conservation of European Wildlife and Wildlife and Their Natural Habitats ) and thus enjoys strict protection within the European Union . The animals may neither be killed nor caught; Owners of this type of snake must submit appropriate certificates of origin and offspring.
supporting documents
literature
- José C. Brito, Hubert Saint Girons: Vipera (Pelias) seoanei Lataste, 1879 - Séoanes Viper, Spanish adder. In: Ulrich Joger, Nicolai Stümpel: Schlangen (Serpentes) III Viperidae. in the series Manual of Reptiles and Amphibians in Europe Volume 3 / IIB. Aula-Verlag, Wiebelsheim 2005; Pages 355-374. ISBN 3-89104-617-0
- David Mallow, David Ludwig, Göran Nilson: True Vipers. Natural History and Toxicology of Old World Vipers. Krieger Publishing Company, Malabar (Florida) 2003; Pages 261-263. ISBN 0-89464-877-2
- Ulrich Gruber: The snakes in Europe and around the Mediterranean. Franckh'sche Verlagsbuchhandlung Stuttgart 1989; Pages 215-216. ISBN 3-440-05753-4
Evidence cited
Most of the information in this article has been taken from the sources given under literature; the following sources are also cited:
- ↑ a b c d All information from Brito & Saint Girons 2005 and Mallow et al. 2003
- ↑ a b c d e f g All information from Brito & Saint Girons 2005
- ↑ Figures rounded off from: F. Braña, A. Bea, H. Saint Girons: Composición de la dieta y ciclos de alimentación en Vipera seoanei Lataste, 1879. Variaciones en relación con la edad y el ciclo reproductor. In: Munibe , 40, 1988, pp. 19–27, full text (PDF; 201 kB)
- ↑ F. Braña, S. Bas: Vipera seoanei cantabrica ssp. n. In: Munibe , 35, 1983, pp. 87-88, full text (PDF; 207 kB)
- ↑ P. Lenk, S. Kalayabina, M. Wink, U. Joger: Evolutionary relationships among the true vipers (Reptilia: Viperidae) inferred from mitochondrial DNA sequences. In: Molecular Phylogenetics and Evolution , 19, 2001, pp. 94-104, full text (PDF)
- ↑ Svetlana Kalyabina-heaps, Silke Schweiger, Ulrich Joger, Werner Mayer, Nicolai Orlov, Michael Wink: phylogeny and systematics of the adders (Vipera berus complex). In: Distribution, ecology and protection of the adder (Vipera berus). Mertensiella 15, 2004 ( summary of the conference report )
- ↑ Vipera seoanei in the Red List of Endangered Species of the IUCN 2007. Posted by: Pleguezuelos, J., Sá-Sousa, P., Pérez-Mellado, V., Marquez, R., Cheylan, M. & Geniez, P., 2006. Retrieved December 5, 2007.
- ↑ Appendix II of the Bern Convention
