OTTOMAN VIPER-Vipera xanthina 
This snake can be distinguished from the other vipers in its European range, as it is the only one that lacks a nose horn.DESCRIPTION: Up to 120cm (4ft). Thick-bodied with no nose horn or characteristic head pattern. The colour is variable, grey, sandy or on the mouth just under the eye. The dark brown stripe on the back is irregular, often broken up into blotches; the underside is grayish, but yellow or orange under the tail.
DISTRIBUTION: Turkey, through Asia Minor into Lebanon and the ex-Soviet Union. 
HABITAT: Found in open woodland, rocky hillsides, pastures and often cultivated areas. A sluggish viper, diurnal normally, but can be active at night during the hotter months.FOOD: Venomous with a bite that could be fatal to human beings. Feeds mainly on mammals and birds but take lizards also.
BREEDING: Live-bearing, averaging around 15 in a litter.
COPPERHEAD-Agkistrodon contortrix
Though painful, the venomous bite of the copperhead rarely causes fatalities.
DESCRIPTION: 61-134cm (2-4 ½ ft). Usually a fairly chunky snake. Often distinguished by a pattern across the back that is dark brown on the tan, orange or grayish ground colour. A pit viper, it has small facial pits; the body scales are weakly keeled.
DISTRIBUTION: Much of southeastern USA, except Florida, and bounded in the west by central Texas and Kansas. 
HABITAT: Found in a variety of habitats from rocky hillsides to lush swamp vegetation, its coloration makes it inconspicuous, but if disturbed it will berate its tail rapidly and will strike swiftly.FOOD: Venomous, eating mainly small mammals, but also lizards, snakes, amphibians and insects such as cicadas.
BREEDING: Live-bearing, the young have bright yellow tail-tips that fade as the snake ages.
NOSE-HORNED VIPER-Vipera ammodytes
Highly venomous, potentially the most dangerous viper in Europe.
DESCRIPTION: Up to 90cm (3ft) long, but more regularly under 65cm (2ft). Stout-bodies with a triangle head, males are more often grey and females browner. A clearly marked zigzag striping is normally unbroken on the back, while the underside is grayish to pink with some darker spotting and red, yellow or green under the tail.
DISTRIBUTION: a southern species, from northern Italy through the Balkans into Greece and South West Asia.HABITAT: Prefers dry, sunny, rocky slopes with some vegetation. Mostly terrestrial, but can climb; usually encountered during the day and when disturbed hisses loudly.
FOOD: Venomous, feeds mostly on small mammals, birds and lizards.
BREEDING: The females bear live young, which are born in late summer.
COTTON MOUTH-Agkistrodon piscivorus
This dangerous snake will often give warming when disturbed by vibrating its tail and gaping its mouth to reveal the “cotton” white interior.DESCRIPTION: 76-189cm (2½-6ft). A large snake that is dark, olive, brown and black above. The cross banding on the back is darker still, but sometimes hard to see, while the belly is usually a little lighter than the back. Care is needed to distinguish it from water snakes, but the presence of facial pits and (on a dead specimen) the single anal scales are diagnostic.
DISTRIBUTION: The southern states of the USA, from Virginia in an arc bounded by the eastern seaboard taking in Florida through to Oklahoma and Texas. 
HABITAT: Semi-aquatic, found in swamps, lakes and ditches. A fairly lethargic snake whose behavior in retreating slowly or standing its ground when disturbed marks it out from the fast-fleeting water snakes, as does its habit of vibrating its tail.FOOD: Venomous, mainly feeding on fish will take birds, mammals and amphibians, as well as baby alligators and turtles.
BREEDING: Live- bearing; gives birth between August and September to up to 15 young. Breeds mainly every other year.
SIDE WINDER-Grotalus cerastes
Famous for its classic mode of locomotion that never allows too much of the body to touch the brning desert surface at any one time.DESCRIPTION: 43-82cm (1½-2½ft). A shortish, stubby and rattlesnakes with prominently rough scales and triangular horns over the eyes.
DISTRIBUTION: Northwestern Mexico, southern parts of Utah, Arizona, Nevada and eastern California. HABITAT: Spends the day hidden in mammal burrows or beneath low bushes; it emerge into its arid desert habitat at night. Often encountered basking at the side of roads during the day otherwise elusive, but the parallel J shaped marking it makes in the sand are a distinctive sign of its presence in an area. FOOD: Venomous; eats pocket mice, kangaroo rats and lizards.
BREEDING: Live- bearing, producing 5-18 young in late summer or early autumns.
TIMBER RATTLE SNAKE-Grotalus horridus
The only rattlesnake in most of northeastern USA, but relatively common only in undisturbed montane area as it has been persecuted in much of the rest of its range. DESCRIPTION: 88 – 189cm (3-6ft). Large variation between southern and northern populations. The head may be unmarked or with a dark stripe behind the eye, the back may be dark with blotches on the side and forming cross bands nearer the fail or it may have a brownish stripe running own it with chevron like cross banding. Both show a black tail.
DISTRIBUTION: Much of eastern USA, from Maitter south to northern Florida, west into Minnesota and Texas. 
HABITAT: Prefers remote areas, wooded hillsides, rock outcrops, swamps and river floodplains. Active between April and October, mostly during daylight but also night during the summer. In October the snakes may congregate in great numbers at favoured hibernation sites.FOOD: Venomous; often waiting perfectly still in order to ambush prey such as squirrels, chipmunks, mice and birds.
BREEDING: Females give birth every other year, producing 5-17 live-born young between late August to October.
WESTERN RATTLESNAKE-Grotalus viridis
One of the most aggressive of the rattlesnakes, its bite can be lethal even if treated.DESCRIPTION: 40-162cm (1½-5½ft). Very variable over much of its range, but often with two diagonal stripes on the head, one above and one below the eye. It is mainly some shade of brown with darker, regular blotches on the back and sides that thin nearer the tail and almost join to become bands. The lighter coloured tail is ringed with black at the base.
DISTRIBUTION: Much of western USA, into northern Mexico and some Sothern parts of western Canada. HABITAT: Mainly crepuscular, preferring rock canyons and scrubby slopes, but often found in agricultural and suburban locations.
FOOD: Venomous, preying chiefly on small rodents.
BREEDING: 4-21 live-born young are produced from August to October, after mating either in autumn or in March or May.
WESTERN DIAMONDBACK RATTLE SNAKE- Crotalus atrox 
Noted for its defensive position when it raises its head well above the coils in a classic S shaped pose and intermittently compounds its threat by rattling its tail.DESCRIPTION: 86-213cm (3-7ft). A large snake with variable coloration, usually brownish with pale-bordered diamond-shape patches on the back. The tail is ringed with black and white bands.
DISTRIBUTION: Southwestern USA and into northern Mexico. HABITAT: Prefers dry or semi-arid areas like canyons and scrubby plains, but also montane locations and river bluffs. A secretive snake, but one that is often in close proximity to areas of human population and is annually persecuted in the “rattlesnake” round-ups.
FOOD: Venomous, feeding on rodents and birds.
BREEDING: 4-25 young are live-born in late summer.
BLACK-TAILED RATTLESNAKE-Grotalus molossus
Possibly the rattlesnake that is least likely to rattle when disturbed.DESCRIPTION: 71-125cm (2-4ft). The body colour varies from grayish-brown to a very back are inevitably darker than the ground colour and with paler centres; they from diamonds nearer the head and thick bands towards the tail. The pattern is usually edged in white or grey and the tail is plan black.
DISTRIBUTION: from Arizona, east into central texas and south into northern Mexico HABITAT: found on cliffs and rock outcrops, often near streams, but also encountered in pine and deciduous woodland.
FOOD: Venomous, feeds on a variety of small rodents.
BREEDING: 3-6 live-born young are born in late summer
MASSASAUGA-Sistrurus catenatus
Differs from all other rattlers by having 9 large scales at the front of the head.
DESCRIPTION: At only up to 100cm (40in), a short, but well- proportioned, snake A light grey to grey-brown snake with a row of large brown, grey or block blotches down the back and smaller and fainter spots on the side. Has a broad dark eye stripe and long mark from the head to the neck, sometime shaped like a lyre.
DISTRIBUTION: Southern Canada (Ontario), southwest to Arizona and northeastern Mexico.HABITAT: prefers moist situations like swamps and around rivers, but in the west it adapts to drier conditions.
FOOD: Venomous, eating lizards, snake small mammals and frogs.
BREEDING: live-bearing; a litter of 2-19 born between July and September.
