- Common names: Timber rattlesnake, canebrake rattlesnake, banded rattlesnake, and others.
Crotalus horridus, the timber rattlesnake, is a
speciesIn biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
of
venomous"Poisonous snake" redirects here. For true poisonous snakes, see Rhabdophis.Venomous snakes are snakes which have venom glands and specialized teeth for the injection of venom...
pitviperThe Crotalinae, commonly known as "pit vipers" or crotaline snakes, are a subfamily of venomous vipers found in Asia and the Americas. They are distinguished by the presence of a heat-sensing pit organ located between the eye and the nostril on either side of the head...
found in the
eastern United StatesThe Eastern United States, the American East, or simply the East is traditionally defined as the states east of the Mississippi River. The first two tiers of states west of the Mississippi have traditionally been considered part of the West, but can be included in the East today; usually in...
. This is the only
rattlesnakeRattlesnakes are a group of venomous snakes of the genera Crotalus and Sistrurus of the subfamily Crotalinae . There are 32 known species of rattlesnake, with between 65-70 subspecies, all native to the Americas, ranging from southern Alberta and southern British Columbia in Canada to Central...
species in most of the populous
northeastern United StatesThe Northeastern United States is a region of the United States as defined by the United States Census Bureau.-Composition:The region comprises nine states: the New England states of Connecticut, Maine, Massachusetts, New Hampshire, Rhode Island and Vermont; and the Mid-Atlantic states of New...
. No subspecies are currently recognized.
Description
Adults usually grow to an average length of 91–152 cm (35.8-59.8 in). The maximum reported length is 189.2 cm (74.5 in)(Klauber, 1956). Holt (1924) mentions a large specimen caught in
Montgomery County, AlabamaMontgomery County is a county in the U.S. state of Alabama. It is the most populous county in the Montgomery Metropolitan Statistical Area; its population in 2010 was 229,363 .- History :...
, that had a total length of 159 cm (62.6 in) and weighed 2.5 kg (5.5 lb).
The
dorsal scalesIn snakes, the dorsal scales are the longitudinal series of plates that encircle the body, but do not include the ventral scales.When counting dorsal scales, numbers are often given for three points along the body, for example 19:21:17...
are
keeledKeeled scales refer to reptile scales that, rather than being smooth, have a ridge down the center that may or may not extend to the tip of the scale, making them rough to the touch...
and arranged in 21-26 scale rows at mid-body (usually 25 in the south and 23 in the north). The
ventral scalesIn snakes, the ventral scales are the enlarged and transversely elongated scales that extend down the underside of the body from the neck to the anal scale. When counting them, the first is the anteriormost ventral scale that contacts the paraventral row of dorsal scales on either side...
number 158-177 in males and 163-183 in females. Males have 20-30
subcaudal scalesIn snakes, the subcaudal scales are the enlarged plates on the underside of the tail. These scales may be either single or divided and are preceded by the anal scale....
while females have 15-26. The rostral scale is normally a little higher than it is wide. In the internasal-prefrontal area there are 4-22 scales that include 2 large, triangular
internasal scalesIn snakes, the internasal scales are those on top of the head between the scales that surround the nostrils. They are usually paired and situated just behind the rostral....
that border the rostral, followed by 2 large, quadrangular
prefrontal scalesThe prefrontal scales on snakes and other reptiles are the scales connected to the frontals towards the tip of the snout which are in contact with the internasals....
(anterior canthals) that may contact each other along the midline, or may be separated by many small scales. Between the
supraocularIn scaled reptiles, supraocular scales are scales on the crown immediately above the eye. The size and shape of these scales are among the many characteristics used to differentiate species from each another....
and internasal, only a single canthal scale is present. There are 5-7
intersupraocular scalesIn snakes, the interorbital scales, or intersupraoculars, are the scales on the top of the head between the plates surmounting the eyes ....
. The number of prefoveal scales varies between 2 and 8. Usually the first
supralabial scaleIn reptiles, the supralabial scales, also called upper-labials, are those scales that border the mouth opening along the upper jaw. They do not include the median scale . The term labial originates from Labium , which refers to any lip-like structure...
is in broad contact with the prenasal scale, although slightly to moderately separated along its posteroventral margin by the most anterior prefoveals.
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-shaped or M-shaped. Often a rust-colored vertebral stripe is present. Ventrally they are yellowish, uniform or marked with black.
MelanismMelanism is an undue development of dark-colored pigment in the skin or its appendages, and the opposite of albinism. It is also the medical term for black jaundice.The word is deduced from the , meaning black pigment....
is common, and some individuals are very dark, almost solid black.
Geographic range
Found in the eastern
United StatesThe United States of America is a federal constitutional republic comprising fifty states and a federal district...
from southern
MinnesotaMinnesota is a U.S. state located in the Midwestern United States. The twelfth largest state of the U.S., it is the twenty-first most populous, with 5.3 million residents. Minnesota was carved out of the eastern half of the Minnesota Territory and admitted to the Union as the thirty-second state...
and southern
New HampshireNew Hampshire is a state in the New England region of the northeastern United States of America. The state was named after the southern English county of Hampshire. It is bordered by Massachusetts to the south, Vermont to the west, Maine and the Atlantic Ocean to the east, and the Canadian...
, south to
east TexasEast Texas is a distinct geographic and ecological area in the U.S. state of Texas.According to the Handbook of Texas, the East Texas area "may be separated from the rest of Texas roughly by a line extending from the Red River in north central Lamar County southwestward to east central Limestone...
and north
FloridaFlorida is a state in the southeastern United States, located on the nation's Atlantic and Gulf coasts. It is bordered to the west by the Gulf of Mexico, to the north by Alabama and Georgia and to the east by the Atlantic Ocean. With a population of 18,801,310 as measured by the 2010 census, it...
The type locality given is "America", although
SchmidtKarl Patterson Schmidt was an American herpetologist.-Biography:Schmidt was the son of George W. Schmidt and Margaret Patterson Schmidt. Schmidt's father was a German professor who, at the time of Schmidt's birth, was teaching in Lake Forest, Illinois. His family left the city in 1907 and settled...
(1953) proposed that this be restricted to "vicinity of
New York CityNew York is the most populous city in the United States and the center of the New York Metropolitan Area, one of the most populous metropolitan areas in the world. New York exerts a significant impact upon global commerce, finance, media, art, fashion, research, technology, education, and...
" (USA).
McDiarmid et al. (1999) also states that its range includes southern
OntarioOntario is a province of Canada, located in east-central Canada. It is Canada's most populous province and second largest in total area. It is home to the nation's most populous city, Toronto, and the nation's capital, Ottawa....
in
CanadaCanada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...
, but in May 2001, the Canadian
Species at Risk ActThe Species at Risk Act is a piece of Canadian federal legislation which became law in Canada on December 12, 2002. It is designed to meet one of Canada's key commitments under the International Convention on Biological Diversity. The goal of the Act is to protect endangered or threatened...
listed it as
extirpatedLocal extinction, also known as extirpation, is the condition of a species which ceases to exist in the chosen geographic area of study, though it still exists elsewhere...
there.
Although several experts disagree, many were found in some of the thick forest areas of central, and southeastern
IowaIowa is a state located in the Midwestern United States, an area often referred to as the "American Heartland". It derives its name from the Ioway people, one of the many American Indian tribes that occupied the state at the time of European exploration. Iowa was a part of the French colony of New...
, mostly within the
MississippiThe Mississippi River is the largest river system in North America. Flowing entirely in the United States, this river rises in western Minnesota and meanders slowly southwards for to the Mississippi River Delta at the Gulf of Mexico. With its many tributaries, the Mississippi's watershed drains...
,
SkunkThe Skunk River is a tributary of the Mississippi River in the state of Iowa in the United States.It rises in two branches, the South Skunk and the North Skunk . The headwaters of the South Skunk are in Hamilton County in north central Iowa. It flows roughly due southward, to the west of...
,
IowaThe Iowa River is a tributary of the Mississippi River in the state of Iowa in the United States. It is about long and is open to small river craft to Iowa City, about from its mouth...
, and
Des Moines RiverThe Des Moines River is a tributary river of the Mississippi River, approximately long to its farther headwaters, in the upper Midwestern United States...
valleys, in several places in these areas, bites from Timber Rattlesnakes have been widespread, especially in a localized area of
Geode State ParkGeode State Park is a state park of Iowa, USA, border Henry County and Des Moines County It is managed by the Iowa Department of Natural Resources. While it is named for Iowa's state rock, the geode , few can be found in the park. A display of geodes, with their mysterious crystal formations in...
, in southeastern
Henry County-2010 census:The 2010 census recorded a population of 20,145 in the county, with a population density of . There were 8,280 housing units, of which 7,666 were occupied.-2000 census:...
, along Credit Island Park, in southern
Scott County-2010 census:The 2010 census recorded a population of 165,224 in the county, with a population density of . There were 71,835 housing units, of which 66,765 were occupied.-2000 census:...
, and in the forested areas of southern
Clinton County-2010 census:The 2010 census recorded a population of 49,116 in the county, with a population density of . There were 21,733 housing units, of which 20,223 were occupied.-2000 census:...
.
In
PennsylvaniaThe Commonwealth of Pennsylvania is a U.S. state that is located in the Northeastern and Mid-Atlantic regions of the United States. The state borders Delaware and Maryland to the south, West Virginia to the southwest, Ohio to the west, New York and Ontario, Canada, to the north, and New Jersey to...
it is not found West of
Chestnut RidgeChestnut Ridge may refer to:* Chestnut Ridge, Bedford County, a mountain ridge in Bedford County, Pennsylvania* Chestnut Ridge, New York, a village in the United States* Chestnut Ridge Park, in Orchard Park, New York...
, which is in the
Laurel HighlandsThe Laurel Highlands is a region in southwestern Pennsylvania made up of Fayette County, Somerset County and Westmoreland County. It has a population of about 600,000 people....
, 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
PennsylvaniaThe Commonwealth of Pennsylvania is a U.S. state that is located in the Northeastern and Mid-Atlantic regions of the United States. The state borders Delaware and Maryland to the south, West Virginia to the southwest, Ohio to the west, New York and Ontario, Canada, to the north, and New Jersey to...
.
Habitat
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 non-gravid females tend to spend more time in cooler, denser woodland with a 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 hibernate in dens, in limestone crevices, often together with
CopperheadCopperhead may refer to:Snakes:* Agkistrodon contortrix, a venomous pit viper species found in parts of North America.* Agkistrodon piscivorus, a.k.a. the cottonmouth, another venomous pit viper species found in North America....
s (
Agkistrodon contortrixAgkistrodon contortrix is a species of venomous snake found in North America, a member of the Crotalinae subfamily. The more common name for the species is "copperhead". The behavior of Agkistrodon contortrix may lead to accidental encounters with humans...
) and
Black Rat SnakeThe Western ratsnake — also called black rat snake, pilot black snake, or simply black snake — is a nonvenomous colubrid species found in North America. No subspecies are currently recognized....
s (Elaphe obsoleta).
Feeding
Their prey is mainly small
mammalMammals are members of a class of air-breathing vertebrate animals characterised by the possession of endothermy, hair, three middle ear bones, and mammary glands functional in mothers with young...
s, but may include small
birdBirds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from...
s,
frogFrogs are amphibians in the order Anura , formerly referred to as Salientia . Most frogs are characterized by a short body, webbed digits , protruding eyes and the absence of a tail...
s, or other snakes. Although capable of consuming other
rattlesnakeRattlesnakes are a group of venomous snakes of the genera Crotalus and Sistrurus of the subfamily Crotalinae . There are 32 known species of rattlesnake, with between 65-70 subspecies, all native to the Americas, ranging from southern Alberta and southern British Columbia in Canada to Central...
s, the most common snakes they eat are
garter snakeThe Garter snake is a Colubrid snake genus common across North America, ranging from Alaska and Canada to Central America. It is the single most widely distributed genus of reptile in North America. The garter snake is also the Massachusettsstate reptile.There is no real consensus on the...
s.
Venom
Potentially, this is one of North America's most dangerous snakes, due to its long fangs, impressive size and high
venom"Poisonous snake" redirects here. For true poisonous snakes, see Rhabdophis.Venomous snakes are snakes which have venom glands and specialized teeth for the injection of venom...
yield. This is to some degree offset by its relatively mild disposition. Before striking, they often do a good deal of preliminary rattling and feinting. Cist (1845) described how he lived in western
PennsylvaniaThe Commonwealth of Pennsylvania is a U.S. state that is located in the Northeastern and Mid-Atlantic regions of the United States. The state borders Delaware and Maryland to the south, West Virginia to the southwest, Ohio to the west, New York and Ontario, Canada, to the north, and New Jersey to...
for many years and that the species was quite common there, but that in all that time he heard of only a single death resulting from its bite.
There is considerable geographic and
ontogeneticOntogeny is the origin and the development of an organism – for example: from the fertilized egg to mature form. It covers in essence, the study of an organism's lifespan...
variation regarding the toxicity of the venom; something that can be said for many rattlesnake species. Four venom patterns have been described for this species: Type A is largely
neurotoxicA neurotoxin is a toxin that acts specifically on nerve cells , usually by interacting with membrane proteins such as ion channels. Some sources are more general, and define the effect of neurotoxins as occurring at nerve tissue...
and is found in various parts of the southern range. One effect of the toxin can be generalized
myokymiaMyokymia, is an involuntary, spontaneous, localized quivering of a few muscles bundles within a muscle, but which are insufficient to move a joint.One type is superior oblique myokymia....
http://www.medscape.com/viewarticle/487281_5. Type B is
hemorrhagicBleeding, technically known as hemorrhaging or haemorrhaging is the loss of blood or blood escape from the circulatory system...
and
proteolyticProteolysis is the directed degradation of proteins by cellular enzymes called proteases or by intramolecular digestion.-Purposes:Proteolysis is used by the cell for several purposes...
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
ArkansasArkansas is a state located in the southern region of the United States. Its name is an Algonquian name of the Quapaw Indians. Arkansas shares borders with six states , and its eastern border is largely defined by the Mississippi River...
and northern
LouisianaLouisiana is a state located in the southern region of the United States of America. Its capital is Baton Rouge and largest city is New Orleans. Louisiana is the only state in the U.S. with political subdivisions termed parishes, which are local governments equivalent to counties...
. 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 A2Phospholipases A2 are enzymes that release fatty acids from the second carbon group of glycerol. This particular phospholipase specifically recognizes the sn-2 acyl bond of phospholipids and catalytically hydrolyzes the bond releasing arachidonic acid and lysophospholipids...
. 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
peptidePeptides are short polymers of amino acid monomers linked by peptide bonds. They are distinguished from proteins on the basis of size, typically containing less than 50 monomer units. The shortest peptides are dipeptides, consisting of two amino acids joined by a single peptide bond...
that works as a
myotoxinMyotoxins are small, basic peptides found in snake venoms, such as in that of certain rattlesnakes. This involves a non-enzymatic mechanism that leads to severe muscle necrosis...
, a
fibrinFibrin is a fibrous, non-globular protein involved in the clotting of blood. It is a fibrillar protein that is polymerised to form a "mesh" that forms a hemostatic plug or clot over a wound site....
ogen-clotting
enzymeEnzymes are proteins that catalyze chemical reactions. In enzymatic reactions, the molecules at the beginning of the process, called substrates, are converted into different molecules, called products. Almost all chemical reactions in a biological cell need enzymes in order to occur at rates...
that can produce
defibrination syndromeDisseminated intravascular coagulation , also known as disseminated intravascular coagulopathy or consumptive coagulopathy, is a pathological activation of coagulation mechanisms that happens in response to a variety of diseases. DIC leads to the formation of small blood clots inside the blood...
, and a
bradykininBradykinin is a peptide that causes blood vessels to dilate , and therefore causes blood pressure to lower. A class of drugs called ACE inhibitors, which are used to lower blood pressure, increase bradykinin further lowering blood pressure...
-releasing enzyme.
CroFabCroFab is the commercial name for a Crotalidae Polyvalent Immune Fab snake antivenom, indicated for minimal or moderate North American Crotalid snake envenomation. It is developed and manufactured by BTG plc , and distributed in the US by Nycomed Inc...
antivenom, while not specific for C. horridus, is used to treat envenomations from this species.
Symbol
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, [see "
Romney, West VirginiaRomney is a city in and the county seat of Hampshire County, West Virginia, United States. The population was 1,940 at the 2000 census, while the area covered by the city's ZIP code had a population of 5,873. It is a city with a very historic background dating back to the 18th century...
"] to have been instrumental in making the timber rattlesnake the state reptile..."
This snake became a prominent symbol during the
American RevolutionThe American Revolution was the political upheaval during the last half of the 18th century in which thirteen colonies in North America joined together to break free from the British Empire, combining to become the United States of America...
in part because it had a fearsome reputation. The use of the timber rattlesnake as a symbol of American anger and resolve to defend itself was no idle threat. During the period of 1763-1787, medical knowledge was not up to the challenge of treating a timber rattlesnake's bite. First of all, at the time, European standards of medical practice were based on the ideas and concepts of
GalenAelius Galenus or Claudius Galenus , better known as Galen of Pergamon , was a prominent Roman physician, surgeon and philosopher...
, where disease was caused by imbalances in the body; this was the standard to which all doctors practicing medicine in the colonies were trained. Because of the then poorly understood effects on the nervous or hematological system of this species' venom, a physician would prescribe a course of action that wound up killing the patient faster (bleeding with leeches) or prescribing herbs without testing of their efficacy as a cure beyond imitation of Native American practices (This was further complicated by the venom's ability to kill within the space of one day in a world where doctors were fewer.) Secondly, Linnaeus only described and identified this snake in 1758: firsthand experience with timber rattlesnakes among London scientists would have been poor, the flora and fauna of the colonies would have been disdained as savage by thinking circles and so published information on its habits would have been thin, allowing for hearsay and superstition to grow on both sides of the Atlantic.
Taxonomy
The subspecies C. h. atricaudatus (
LatreillePierre André Latreille was a French zoologist, specialising in arthropods. Having trained as a Roman Catholic priest before the French Revolution, Latreille was imprisoned, and only regained his freedom after recognising a rare species he found in the prison, Necrobia ruficollis...
in
SonniniCharles-Nicolas-Sigisbert Sonnini de Manoncourt was a French naturalist. Between 1799 to 1808 he wrote 127 volumes of the Histoire naturelle. Noteworthy among these, especially for herpetologists, is Histoire naturelle des Reptiles, avec figures desinées d'après nature, in four volumes, which he...
and Latreille, 1802), often referred to as the canebrake rattlesnake, is currently considered invalid. Previously, it was recognized by
GloydHoward Kay Gloyd was an American herpetologist who is credited with describing several new species of reptile, such as the Florida Cottonmouth, Agkistrodon piscivorus conanti...
(1936) and
KlauberLaurence M. Klauber , was an American herpetologist, and was considered to be the foremost authority on rattlesnakes...
(1936). Based on an analysis of geographic variation, Pisani et al. (1972) concluded that no subspecies should be recognized. This was rejected by
ConantRoger Conant was an American herpetologist, author, educator and conservationist. He was Director Emeritus of the Philadelphia Zoo and Adjunct Professor at the University of New Mexico...
(1975), but followed by Collins and Knight (1980). Brown and Ernst (1986) found evidence for retaining the two subspecies, but state that it is not possible to tell them apart without having more information than usual, including adult size, color pattern, the number of
dorsal scaleIn snakes, the dorsal scales are the longitudinal series of plates that encircle the body, but do not include the ventral scales.When counting dorsal scales, numbers are often given for three points along the body, for example 19:21:17...
rows and the number of
ventral scalesIn snakes, the ventral scales are the enlarged and transversely elongated scales that extend down the underside of the body from the neck to the anal scale. When counting them, the first is the anteriormost ventral scale that contacts the paraventral row of dorsal scales on either side...
. Dundee and Rossman (1989) recognized atricaudatus, but others take a more neutral point of view.
Conservation status
This species is classified as "least concern" on the
IUCNThe International Union for Conservation of Nature and Natural Resources is an international organization dedicated to finding "pragmatic solutions to our most pressing environment and development challenges." The organization publishes the IUCN Red List, compiling information from a network of...
Red List of Threatened SpeciesThe IUCN Red List of Threatened Species , founded in 1963, is the world's most comprehensive inventory of the global conservation status of biological species. The International Union for Conservation of Nature is the world's main authority on the conservation status of species...
. Species are listed as such due to their wide distribution, presumed large population, or because it is unlikely to be declining fast enough to qualify for listing in a more threatened category. The population trend is down. Year assessed: 2007.
The timber rattlesnake is listed as endangered in New Jersey, Vermont, Massachusetts, New Hampshire, Indiana and Ohio, and it is threatened in New York, Connecticut, Illinois, Minnesota and Texas.
External links