蝰蛇一般指属蝰蛇科的200多种毒蛇,共分两个亚科。它们的特点是上颚的活动骨上有一对喷射毒液的长毒蓰,不用的时候可以收拢起来藏入嘴中。响尾蛇除了这个特征以外,还有一个特征,就是在鼻孔和两个眼睛之间各有一个小颊窝。里面有热传感器,能够帮助响尾蛇捕捉温血动物。
蝰蛇最小的体长不到30厘米,最长的超过3米。它们主要食小的动物。
旧大陆的蝰蛇分布在亚洲、非洲和欧洲。它们的样子粗壮、头宽、行动缓慢。许多种是陆栖性蛇类。树栖性蝰比较细长一些,尾巴善于盘抓。
The adder is the only poisonous snake native to Britain. Adders have the most highly developed poison injecting mechanism of all snakes, but they are not aggressive animals. Adders will only use their poison as a last means of defence, usually if caught or trodden on. No one has died from adder bite in Britain for over 20 years. With proper treatment, the worst effects are nausea and drowsiness, followed by severe swelling and bruising in the area of the bite. Most people who are bitten were handling the snake. Treat adders with respect and leave them alone.
Name
Adder (Vipera berus)
Lifestyle
Habitat
Adders are relatively common in areas of rough, open countryside and are often associated with woodland edge habitats. They are less inclined to disappear into the surrounding undergrowth when disturbed and so are probably the most frequently seen of the three British snakes. The best time to see them is in early spring when they emerge from their hibernation dens. By mid April, the males have shed their dull winter skin and are ready to mate. There is a lot of frenzied activity on warm days, with males looking for females and occasionally wrestling with other males for supremacy. The 'dance of the adders' was thought to be a mating display, but it is a larger male attempting to drive off a smaller one. The snakes writhe around each other in an impressive way, often covering the ground at great speed.
Breeding
Following mating, females seek out a suitable place to give birth, often travelling over 1 kilometre from the hibernation site. Births take place in late August / early September. Unlike most reptiles, adders do not lay eggs. Young snakes are born about the size and shape of an earthworm, but a perfect miniature of the adult snake.
Development
During the autumn, adult snakes follow scent trails left by other adders to find their way back to the hibernation site, which is often used by many snakes over several years. The young adders tend to hibernate in the area where they were born. Their survival largely depends on the severity of the weather in the following winter.
Diet
Adders usually eat small rodents, such as the short-tailed vole. They will also eat lizards, frogs and newts, and have been seen taking young from the nests of ground nesting birds. When hunting, adders strike swiftly at the prey, injecting a lethal dose of poison. They then wait until the prey dies before starting the often lengthy swallowing process. Like all snakes, adders eat their prey whole, their teeth are designed to grip the prey as it is swallowed. Their jaws are linked by extensible connective tissue so each of the four main bones can move independently. This means they are able to swallow items much larger than the width of their head. The lower ends of the ribs are not joined as in most animals and can also open out considerably. The adder's digestive fluid is amazingly powerful and will digest the flesh and bones of their prey almost completely. Only the hair and teeth of rodents pass through intact.
Threats
Young adders are threatened by a variety of predators, including birds of prey such as the common buzzard and sometimes adult snakes. Others may be killed and eaten by rodents while in hibernation. Adders are protected by law against being killed or injured through human activity.
Identification
Most adders are distinctively marked with a dark zigzag running down the length of the spine and an inverted 'V' shape on the neck. Males are generally white or pale grey with a black zigzag. Females are a pale brown colour, with a darker brown zigzag. But some adders are entirely black and can be mistaken for some other species.
How we manage our woods
Most of the woods managed by the Forestry Commission are suitable for adders. The way we manage the woods - cutting down older trees and planting young trees - provides excellent habitat. For the first 10 years as the young trees grow, adders can build up large populations unseen. Then as the tree canopy closes overhead, the snakes seek out the light and warmth that is available at the woodland edge.
The adder or Northern viper (Vipera berus) has been recorded at five sites in Cheshire since 1995. It is considered to be of rare occurrence in the county although this may be due, in part, to a limited survey. Adders were recorded in the Cheshire region in the 1950s, although there seem to be only two records documented, neither of which make up any part of the post 1995 picture. Local unofficial sightings are commonplace but given that most turn out to be grass snakes (Natrix natrix), it is essential that these are looked into and the correct identification carried out. A Presence/Absence survey is required and results documented. Numbers and frequency can then be investigated in the future based on such results.
The most important records from Risley Moss LNR and National Trust properties on the Mid-Cheshire Ridge suggest that populations have survived in these areas for some time, and are relatively stable.
The adder is found in a variety and may crop up virtually anywhere, but dry grassland, scrub, heathland, moorland and open woodland are favourite. The vegetation cover and elevated nature of railway embankments may make this habitat the most important in terms of the widespread distribution of this species locally. Prey animals include viviparous lizard (Lacerta vivipara), slow worm (Anguis fragilis), various small mammals and the chicks of ground nesting birds. Therefore it is reasonable to expect two or more of the above at localities favoured by this species.
Adders are protected under the Wildlife and Countryside Act 1981 Schedule 5, Section 9, against intentional killing or injury. Trade in adders is also prohibited.
THREATS
Disturbance and possible persecution by man.
Loss of food animals further down the food chain.
Loss of habitat due to human impact on recreational areas.
Loss of habitat due to constructional development, agriculture and pollution.
CURRENT ACTION
Cheshire and Wirral Amphibian and Reptile Group along with Cheshire Wildlife Trust, conduct recorder training events to encourage awareness of reptiles in the county, training on survey, identification and recording method for the more secretive species.
The Risley Moss staff are aware of the group's activities, as are the National Trust staff responsible for the management of sites containing adders. Some survey work has been carried out and more work of this nature is planned.
The Local Records centre, rECOrd, is producing a Provisional Atlas of Amphibian and Reptile sightings. Please send all sightings to rECOrd.
http://www.adder.net.pl/