|At Jacksonville Zoo and Gardens|
The timber rattlesnake, canebrake rattlesnake or banded rattlesnake (Crotalus horridus),  is a species of venomous pit viper endemic to the eastern United States. This is the only rattlesnake species in most of the populous northeastern United States and is second only to the related prairie rattlesnake as the most northerly distributed venomous snake in North America.   No subspecies are currently recognized. 
The subspecies C. h. atricaudatus ( Latreille in Sonnini and Latreille, 1802), often referred to as the canebrake rattlesnake,  is currently considered invalid.  Previously, it was recognized by Gloyd (1936) also Klauber (1936). Based on an analysis of geographic variation, Pisani et al. (1972) concluded no species should be recognized. This was rejected by Conant (1975), but followed by Collins and Knight (1980). Brown and Ernst (1986) found evidence for retaining the two subspecies, but state it is not possible to tell them apart without having more information than usual, including adult size, color pattern, the number of dorsal scale rows, and the number of ventral scales. Dundee and Rossman (1989) recognized C. h. atricaudatus, but others take a more neutral point of view. 
Adults usually grow to total length of 92–152 cm (36–60 in).  In Pennsylvania, the smallest female that could produce viable young was found to be 72.2 cm (28.4 in).  Most adult timber rattlesnakes found measure less than 100 to 115 cm (39 to 45 in) in total length and weigh typically between 500 and 1,500 g (1.1 and 3.3 lb), often being towards the lower end of that weight range.     The maximum reported total length is 189.2 cm (74.5 in).  Holt (1924) mentions a large specimen caught in Montgomery County, Alabama, which had a total length of 159 cm (62.5 in) and weighed 2.5 kg (5.5 lb).  Large specimens can reportedly weigh as much as 4.5 kg (9.9 lb). 
The dorsal scales are keeled  and arranged in 21–26 scale rows at midbody (usually 25 rows in the southern part of its geographic range, and 23 rows in the northern part). The ventral scales number 158-177 in males and 163–183 in females. Males have 20–30 subcaudal scales, while females have 15–26. The rostral scale is normally a little higher than it is wide. In the internasal-prefrontal area, four to 22 scales are seen, including two large, triangular internasal scales that border the rostral, followed by two large, quadrangular prefrontal scales (anterior canthals) that may contact each other along the midline, or may be separated by many small scales. Between the supraocular and internasal, only a single canthal scale is present. Five to seven intersupraocular scales are noted. The number of prefoveal scales varies between two and eight. Usually, the first supralabial scale is in broad contact with the prenasal scale, although slightly to moderately separated along its posteroventral margin by the most anterior reveals. 
Dorsally, they have a pattern of dark brown or black crossbands on a yellowish-brown or grayish background. The crossbands have irregular zig-zag edges, and may be V- or M-shaped. Often, a rust-colored vertebral stripe is present. Ventrally, they are yellowish, uniform, or marked with black.  Melanism is common, and some individuals are very dark, almost solid black. 
Found in the eastern United States from southern Minnesota and southern New Hampshire, south to East Texas and north Florida,  115 rattlesnakes have been marked within Brown County State Park in Indiana, one of the only places where they can be found in the state. 
Its historic range includes southern Ontario and southern Quebec in Canada,  but in May 2001, the Canadian Species at Risk Act listed it as extirpated in Canada.  A Canadian government-sponsored recovery strategy is currently under study to support the reintroducing of this predator of many pests to its former Canadian habitat.
Although several experts disagree, many were found in some of the thick forest areas of central and southeastern Iowa, mostly within the Mississippi, Skunk, Iowa, and Des Moines River valleys, in several places in these areas; bites from timber rattlesnakes have been widespread, especially in a localized area of Geode State Park, in southeastern Henry County, along Credit Island Park, in southern Scott County, and in the forested areas of southern Clinton County.[ citation needed]
In Pennsylvania, it is not found west of Chestnut Ridge, which is in the Laurel Highlands, nor is it found in the southeastern corner of the state. Thus, its range does not include the areas of Philadelphia and Pittsburgh, the two largest cities in Pennsylvania. 
C. horridus is extirpated in Maine and Rhode Island and is almost extirpated in New Hampshire.
In Massachusetts, the snakes are active from mid-May to mid-October.  Early settlers were afraid of the snake, as its population was widespread throughout the state. Since that time, their habitat has been reduced to the Blue Hills south of Boston, the Berkshires in Western Massachusetts, and parts of the Connecticut River Valley, notably in the area of the Holyoke Range.  The snake is so rare in the state that it is rarely encountered by people and is considered endangered, making it illegal to harass, kill, collect, or possess. 
Generally, this species is found in deciduous forests in rugged terrain. During the summer, gravid (pregnant) females seem to prefer open, rocky ledges where the temperatures are higher, while males and nongravid females tend to spend more time in cooler, denser woodland with more closed forest canopy. 
Female timber rattlers often bask in the sun before giving birth, in open rocky areas known as "basking knolls".  During the winter, timber rattlesnakes brumate in dens, in limestone crevices, often together with copperheads and black rat snakes.  As with all snakes, they are ectothermic. As with most rattlesnakes females give birth to live young and typically this happens during the fall in private dens located in rocky fields; the family stays together until spring. In warmer weather timber rattlesnakes prefer to seek sunlight on rocky ridges or stone strewn areas to recharge themselves for the day ahead and seek prey in the underbrush. Though they do not enjoy it in particular, they are excellent swimmers and they undulate their bodies, moving similar to a crocodile in water but with their rattles easily seen sticking out of the water. They can and will take to water readily if they desire food, new territory, or a mate; like the larger eastern diamondback with which they share the Southern half of their range they have been recorded slithering on the beach and jumping into the surf for to swim in the sea, diving under the waves until the water is sound enough to carry them. 
Their prey is mainly small mammals, but may include small birds, frogs, bird eggs, and other small animals, including other snakes or the occasional house rat if they can find one. Although capable of consuming other rattlesnakes, the most common snake they prey upon are garter snakes.  Like most rattlesnakes, timber rattlesnakes are known to use chemical cues to find sites to ambush their prey and often strike their prey and track them until they can be consumed.   Timber rattlesnakes are known to use fallen logs or abandoned stone walls as a waiting site for prey to pass by, giving them an elevated perch from which to effectively strike their prey, which is almost entirely terrestrial rather than arboreal (even arboreal prey such as squirrels tends to be caught when they come to the ground).   The primary foods by genera of timber rattlesnakes were as follows: Peromyscus (33.3%), Microtus (10.9%), Tamias (qv) (10.6%), Sylvilagus (10.4%), Sigmodon (5.3%) and Sciurus (4.2%). Based on examination of the snout-to-vent length, juvenile timber rattlesnakes were found to differ slightly in dietary preferences from adult rattlesnakes, being more likely to consume smaller prey such as shrews (averaging 8 g (0.28 oz) and unable to attack subadult eastern cottontail rabbits (typically 500–1,000 g (1.1–2.2 lb), but Peromyscus was the number one prey item for both young and adult rattlesnakes. Several birds, although always secondary to mammals, are also known to be hunted, mainly ground-dwelling species such as bobwhites, but also a surprising number of passerines. 
Potentially, this is one of North America's most dangerous snakes, due to its long fangs, impressive size, and high venom yield. The snake is most deadly to adult males who become overconfident in their abilities or have imbibed too much alcohol and have badly impaired their judgment, according to 1997 statistics from one hospital in the USA.  Children must be taught to recognize this snake and mind where they step in rock strewn areas; they must be told to never touch or disturb it for any reason and slowly back away from it, since it takes less time for the venom to circulate through their bloodstream if bitten. Dogs should be taken to the veterinarian right away should a timber rattlesnake bite them as they are also susceptible to all types of rattlesnake venom.
However, despite all this, they have a very meek disposition and shall strike only if molested or frightened.  They have a long brumation period because their natural habitat is too cold for large portions of the year and thus they require rocky dens to stay warm in. Temperamentally, they are not like their kin West of the Mississippi River in the sense that those rattlesnakes do not have the luxury of having many places to hide except for burrows or dry sparse vegetation. Cousins to the timber rattlesnake like the Western diamondback have to be more aggressive to survive and have to stand their ground more often to avoid getting stepped on or eaten by raptors. A timber rattlesnake, by contrast, will sit there still, silent, hopeful it has not been seen, and have many options in terms of places to hide, up to and even including lakes and rivers to dive in. They prefer to flee rather than fight and are terrified of anything bigger than they are since they think that the bigger animal, man included, will try to eat them. If a timber rattlesnake knows it has been seen, it often performs a good deal of preliminary rattling and feinting before striking. Even where abundant they are not easy to locate as they are extremely shy. Cist (1845) described how he lived in western Pennsylvania for many years, and the species was quite common there, but in all that time, he heard of only a single death resulting from its bite. 
Considerable geographic and ontogenetic variation occurs regarding the toxicity of the venom, which can be said for many rattlesnake species. Four venom patterns have been described for this species: Type A is largely neurotoxic, and is found in various parts of the southern range. One effect of the toxin can be generalized myokymia.  Type B is hemorrhagic and proteolytic, and is found consistently in the north and in parts of the southeast. Type A + B is found in areas where the aforementioned types apparently intergrade in southwestern Arkansas and northern Louisiana. Type C venom has none of the above components and is relatively weak. 
The neurotoxic component of the type A venom is referred to as canebrake toxin, and is a phospholipase A2. It is analogous to the neurotoxins found in the venoms of several other rattlesnake species, and when present, contributes significantly to the overall toxicity. Other components found in the venom include a small basic peptide that works as a myotoxin, a fibrinogen-clotting enzyme that can produce defibrination syndrome, and a bradykinin-releasing enzyme. 
The timber rattlesnake was designated the state reptile of West Virginia in 2008.  That state's legislature praised "...a proud contribution by the eighth grade class at Romney Middle School, from West Virginia's oldest county, in West Virginia's oldest town, to have been instrumental in making the timber rattlesnake the state reptile..." 
This snake became a prominent symbol of American anger and resolve during the American Revolution due to its fearsome reputation. In the 18th century, European-trained doctors and scientists had little firsthand experience with or information on timber rattlesnakes,  and treatment of their bites was poorly effective. The motto Nemo me impune lacesset (with the verb in the future tense) appears above a C. horridus on a 1778 $20 bill from Georgia as an early example of the colonial use of the coiled rattlesnake symbol, which later became famous on the Gadsden flag.
This species is classified as least concern on the IUCN Red List (assessed in 2007).  Species are listed as such due to their wide distribution, presumed large population, or because they are unlikely to be declining fast enough to qualify for listing in a more threatened category. 
The timber rattlesnake is listed as endangered in New Jersey, Vermont, Massachusetts  (along with the copperhead viper), Virginia, New Hampshire, Indiana,  and Ohio, and it is threatened in New York, Connecticut, Illinois, Minnesota, and Texas.[ citation needed]
Timber rattlesnakes have already been extirpated in Maine, Rhode Island, and Ontario and only one population remains in New Hampshire. They are protected in many of the Appalachian states, but their populations continue to decline. 
- List of crotaline species and subspecies
- Crotalus by common name
- Crotalus by taxonomic synonyms
- Crotalinae by common name
- Crotalinae by taxonomic synonyms
- Gadsden flag
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