Timber Rattlesnake
Crotalus horridus

*** VENOMOUS ***

Venomous Snake Bite Information

Common Name:

Timber Rattlesnake

Scientific Name:

Crotalus horridus

Etymology:

Genus:

Crotalus is derived from the Latin word crotalum which means "rattle".

Species:

horrid is Latin for 'dreadful'.

Vernacular Names:

American viper, bastard rattlesnake, black rattlesnake, common rattlesnake, eastern rattlesnake, great yellow rattlesnake, mountain rattlesnake, northern banded rattlesnake, northern rattlesnake, pit viper, rock rattlesnake, velvet tail, yellow rattlesnake.

Average Length:

30 - 60 in. (90 - 152 cm)

Virginia Record Length:

67.1 in. (170.5 cm)

Record length:

74.5 in. (189.2 cm)

Timber rattlesnake populations

Virginia Wildlife Action Plan Rating Tier IV - Moderate Conservation Need - The species may be rare in parts of its range, particularly on the periphery. Populations of these species have demonstrated a significant declining trend or one is suspected which, if continued, is likely to qualify this species for a higher tier in the foreseeable future. Long-term planning is necessary to stabilize or increase populations.

PHYSICAL DESCRIPTION: Rattlesnakes have the following characteristics that distinguish them from similar looking non-venomous snakes: 1) short tail and rattle, 2) single row of transverse scales on underside of tail, 3) stout bady girth, 4) facial pit, 5) small dorsal head scales, and 6) vertical pupils of the eyes. The length of this species is from 10-60 inches with the maximum of 6 feet. Males are generally larger than females, and southern populations are typically larger than northern populations. Adult males tend to be 12% longer than adult females. *12045* There are two major color phases though individuals vary along a continuum between the light and dark phase. The yellow morph or phase is characterized by a yellow or tan ground color with dark brown or gray bands. There is occasionally a dorsal rust-colored band and a yelow or tan head. The belly is yellowish cream in color and the tail is a uniform black. The dark or black morph is characterized by a black ground color with black or dark gray dorsal bands or blotches. Occasionally, a dorsal rust colored band is present. The head is black or gray. The belly is mottled yellow-gray and the tail is uniformly black. Prior to their neonatal molt, newborn timber rattlesnakes are best described as gray. Newborns may have a distinctive reddish mid-dorsal stripe. Following the neonatal molt and certainly by the age of 1 year, adult coloration is evident. *11644,10760,12045,1014*

REPRODUCTION: Timber rattlesnakes have the following life history characteristics: low reproductive rate, stochastic reproductive events, high mortality in juveniles, low adult mortality, and a long natural lifespan. Breeding season lasts from approximately late July to mid-September. Spring mating is rare and has not been reported in the Appalachians. Males exhibit ritual fighting and territoriality during the mating season and may travel as far as 4 miles during the breeding season in search of females. Timber rattlesnakes give birth to live young from August to October with most births occurring between late August and early September. Females typically become sexually mature between 4 and 5 years of age; males become sexually mature between 3 and 4 years old. However, they do not usually breed before 6 years of age. Brown (1991) found that 57% of females reproduced at 3 year intervals and that 27% reproduced at 4 year intervals. The average interval in Virginia is 3.3 years. Timber rattlesnakes may continue to breed into their 30's. Average litter size is 8, but ranges from 3 to 18. Births take place in historic communal rookeries located at or near den sites *10760* *11644* *10305*.

BEHAVIOR: A lot of variation has been reported in the home range size of timber rattlesnakes. Studies in New Jersey and Pennsylvania have reported the following range in mean home range size: males, 65 to 207 ha; nongravid females, 17 to 42 ha; and gravid females, 4 to 22 ha. Males will exhibit some territoriality and ritual fighting during the mating season. Males may also travel up to 4 miles over the course of the breeding season in search of females. Nongravid females typically travel 0.75-1.25 mi from the den, while gravid females stay within 0.5 mi of the den. Even outside of the breeding season, males will travel significantly from the den site, often up to 2 miles distant. Timber rattlesnakes overwinter and typically breed in communal dens. Individual rattlesnakes display high fidelity to communal dens and birthing rookeries. Hibernation averages 204 days in length, usually October 10 to May 1. Most overwintering den sites are located in crevices in rock ledges or talus slopes. Depth of the crevice is apparently important in site selection. In addition, most sites have southerly or westerly aspect, however, easterly and northwesterly aspect is not uncommon. Preferred dens are found on steep slopes of 30-45 degrees where the most direct winter sun occcurs. Also, such dens are found in sandstones, quartzites, granites, gneisses, and metabasalts and are at elevations of 200 to 1200 meters. The three basic types of dens include: fissure or fissures in a ledge, bare rock talus or scree, and talus or scree partially covered with soil. As noted, these dens are frequently used as communal rookeries. The young, averaging about 11 inches in length, will stay with their mother at the den site until their first molt at 1 or 2 weeks old. At this first molt, the rattlesnake acquires its first permanent rattle. The mother and young will then leave the den to forage until hibernation. Young that are born in late September or early October will go directly to the hibernacula dens and not forage. Young follow adult scent trails to the hibernacula. Young rattlesnakes will typically shed 1 or two more times during their first full summer, reaching a length of about 18 inches prior to hibernation. The following summer they will again shed one or two more times and reach a length of about 24 inches. Timber rattlesnakes will forage in just about any terrestrial habitat. They commonly coil along rodent scent trails and rest their heads on logs or on tree trunks. Post-emergent and pre-shed snakes and gravid females use well-exposed rocks and occasional logs as basking sites. Timber rattlesnakes will begin emerging from the overwintering dens at mid-day early in the spring. General emergence is recorded in Virginia from 18 April to 12 May and is usually diurnal. Initially, movements are near the den with major migration occurring during late May-June when summer-like weather prevails. Foraging occurs primarily from mid-May through August though young and post-partum females may forage in the fall. During warm summer weather, rattlesnakes are active day and night. Gravid females can often be found basking in the morning or all day on cloudy days. Migration toward dens occurs in September with most snakes entering hibernation during early and mid-October. All of the timber rattlesnakes activities and periodicity are highly temperature dependent. Of 115 hibernacula that were studied, all were within 500 meters of exposed basking areas. Space between these dens averaged at the following distances: 1.68 km among 99 dens in Shenandoah, Virginia (range of 0.25-4.5 km); and 0.95 km among 19 dens in Catoctin, Maryland (range of 0.35-3.2 km). The number of snakes in most dens ranged around 30 to 60 individuals. Lesser numbers of copperheads (Agkistrodon contortrix mokasen) shared some of the dens, while several species of non-venomous snakes shared some of the dens, as well. Of the non-venomous species, the eastern rat snake ) was most frequently observed sharing dens with timber rattlesnakes. The first warm, humid, summer-like evenings seem to trigger the start of the spring migration and foraging period. Dens and spring basking areas were usually deserted by about mid-May, in Martin's studies. Most timber rattlesnakes, except for gravid females and pre-molt individuals, experience a peak in activity that usually occurs around the second week of June. Though, sometimes this peak would take place as early as late May or as late as early July. In June, ecdysis, or shedding, peaks according to records that show 57% of snakes underwent ecdysis at this time. According to Sealy's study in the upper piedmont of North Carolina, 1.22 sheds per year was the mean adult shedding rate. Adult snakes averaged one shed per year for each of three or four successive years, then twice in the fourth or fifth year, which equaled an average of 1.2 sheds per year. *10760,11384,11644,12043,12045*

ORIGIN: Native

LIMITING FACTORS: In western Virginia, timber rattlesnakes require long term stable overwintering shelter, a wooded area for foraging, and human disturbance of both of these habitats should be kept at a minimum *11644*.

POPULATION PARAMETERS: Timber rattlesnake populations are relatively stable on most public lands, however, there has been a drastic decline in the Piedmont region *11644*. Mortality is high (33%) during the first year and declines to about 10% as adult. There is a consensus among most scientists andobservers that the timber rattlesnake is declining over most parts of its range *11644*. Sampling shows a sex ratio of about 2:1 (females:males). However, this may be an artifact of sampling as gravid females are more frequently found basking. The turnover rate of the populations in Virginia is about 10-12%

References for Life History

  • 882 - Conant, R., 1958, A field guide to reptiles and amphibians of the United States and Canada east of the 100th Meridian, 366 pgs., Houghton Mifflin Co., Boston, MA
  • 883 - Conant, R., 1975, A field guide to reptiles and amphibians of Eastern and Central North America, 429 pgs., Houghton Mifflin Co., Boston, MA
  • 1008 - Barbour, R.W., 1971, Amphibians and reptiles of Kentucky, 334 pgs., Univ. of Kentucky Press, Lexington, KY
  • 1013 - Jackson, J.J., 1983, Snakes of the Northeastern United States, 111 pgs., Ext. Serv., Univ. of GA, Athens, GA
  • 1014 - Martof, B.S., Palmer, W.M., Bailey, J.R., Harrison, III J.R., 1980, Amphibians and Reptiles of the Carolinas and Virginia, 264 pgs., UNC Press, Chapel Hill, NC
  • 1100 - Klauber, L. M., 1972, Rattlesnakes , 2nd ed., Vol. 1, 740 pgs., Zoological Soc. San Diego, Univ. Calf. Press
  • 1101 - Mitchell, J. C., 1974, Snakes of Virginia, Virginia Wildl., Vol. 35, Num. 2, pg. 16-19
  • 2075 - Wright, A.H., Wright, A.A., 1957, Handbook of snakes of the United States and Canada, Vol. 1, 564 pgs., Comstock Publ., Ithaca, N.Y
  • 2079 - McCoy, C.J., 1975, Timber rattlesnake, Pennsylvania Forest Resources (21):1-4, 4 pgs., Penn. State. Coop. Ext. Ser., University Park
  • 10305 - Brown, W. S., 1991, Female reproductive ecology in a northern population of the timber rattlesnake, crotalus horridus, Herp., Vol. 47, Num. 1, pg. 101-115
  • 10760 - Mitchell, J. C., 1994, The Reptiles of Virginia, 352 pgs., Smithsonian Institution Press, Washington, DC
  • 11384 - Brown, William S., Joseph T. Collins (Ed.), 1993, Biology, status, and management of the Timber Rattlesnake (Crotalus horridus): A guide for conservation, Num. 22, 78 pgs., Society for Study of Amphibians and Reptiles
  • 11644 - Martin, W.H., 2001, Personal communication: Gap Analysis Project, WV
  • 12043 - Martin, W. H., J. A. Campbell, E. D. Brodie, Jr. (Ed.), 1992, Phenology of the timber rattlesnake (Crotalus horridus) in an unglaciated section of the Appalachian Mountains, Biology of the Pitvipers, pg. 259-277, Selva Press, Tyler, TX
  • 12045 - Sealy, J. B., G. W. Schuett, M. Hoggren, M. E. Douglas, H. Greene (Ed.), 2001, Ecology and behavior of the timber rattlesnake (Crotalus horridus) in the upper Piedmont of North Carolina: Identified threats and conservation recommendations, Biology of the Vipers, Eagle Mountain Publishing, Eagle Mountain, UT

Southeastern "Canebrake" populations

Virginia Wildlife Action Plan Rating Tier II - Very High Conservation Need - Has a high risk of extinction or extirpation. Populations of these species are at very low levels, facing real threat(s), or occur within a very limited distribution. Immediate management is needed for stabilization and recovery.

PHYSICAL DESCRIPTION: In Virginia, most adults are 1.2-1.4 meters in total length *11623*. The head is triangular and pits are located below the midpoints between each eye and nostril *11623,9286*. There is a postocular stripe that varies from light orange to dark brown and a reddish middorsal stripe that extends for the entire length of the body *882,11623*. The pupil of the eye is vertical and elliptical. The tial is tipped with a rattle. The body color is pinkish, gray, yellow, or light brown with a series of black chevrons. The ventor is cream in color and may be lightly peppered with black. The tail is black. Males grow to larger sizes than females. Males in South Carolina were 1220-1400 mm in snout-vent length (SVL) and 1235-2490 gram in body weight compared to females of 1170-1280 mm SVL and 1033-1546 gram body weight. Juveniles are 305-356 mm total length at birth and are patterned as the adults and are usually pinkish. Neonates possess a prebutton prior to the first shed, and a single button appears after the first shed. Additional segments forming the rattle are added at each ecdysis *11623,9286*.

REPRODUCTION: According to Savitzky's research of the populations in southeastern Virginia, most females are suspected to reproduce approximately every 4 years, or possibly every 3 to 5 years *11623*. They bear their young live and have litters of seven to 16 young *9286,11623*. The females give birth to their first litter in their sixth year when they reach a length of about 40 inches *9286,10760*. The males are sexually mature in their fourth year. Courtship and mating occur in mid-summer to early fall of the year before birth *11623*. The young are born in late August or early September *1023,1101,858,10760*.

BEHAVIOR: This species is diurnal in the spring and fall, crepuscular and nocturnal in the summer *1023,946*. Snakes enter hibernacula in October or November and emerge in March, April, or May *11623*. Unlike the communal den characteristic of the timber rattlesnake, overwintering occurs singly or in small numbers in stumps. This species is usually terrestrial but will ascend low shrubs. They are primarily tertiary level predators of small mammals but will consume other vertebrates. They are known to eat squirrels, rats, mice, cottontail rabbits, six-lined racerunners, skinks and birds. They are not territorial *9286,11623*.

LIMITING FACTORS: This species is found in swamps, canefields, low pine woods, canebrakes, cedar brakes, moist woodlands and flood plains, and open areas with little understory *1101,882,858,11623*. Stumps and logs are prefered *1023*. They also inhabit creek bottoms, rocky ridges, cultivated and overgrown fields, under the floors of deserted cabins, thickly wooded areas, and areas full of fallen logs and weeds *946,1100,11623*. It likes higher ridges that adjoin river swamps *1023*.

AQUATIC/TERRESTRIAL ASSOCIATIONS: Individuals are occasionally killed by deer, sheep, dogs, hogs, and red-tailed hawks. Juveniles are known to be eaten by chickens and turkeys *9286,10760*. Humans are the major predator of this species *11623*.

References for Life History

  • 882 - Conant, R., 1958, A field guide to reptiles and amphibians of the United States and Canada east of the 100th Meridian, 366 pgs., Houghton Mifflin Co., Boston, MA
  • 1023 - Williamson, G.M., Linzey, D.W. (Ed.), 1979, Canebrake rattlesnake from the Proceedings of the Symposium on Endangered and Threatened Plants and Animals of Virginia, pg. 407-409,, 665 pp pgs., Ext. Div., VA Tech, Blacksburg, VA
  • 1100 - Klauber, L. M., 1972, Rattlesnakes , 2nd ed., Vol. 1, 740 pgs., Zoological Soc. San Diego, Univ. Calf. Press
  • 1101 - Mitchell, J. C., 1974, Snakes of Virginia, Virginia Wildl., Vol. 35, Num. 2, pg. 16-19
  • 9286 - Terwilliger, K.T., 1991, Virginia's endangered species: Proceedings of a symposium. Coordinated by the Virginia Dept. of Game and Inland Fisheries, Nongame and Endangered Species Program, 672 pp. pgs., McDonald and Woodward Publ. Comp., Blacksburg, VA
  • 10760 - Mitchell, J. C., 1994, The Reptiles of Virginia, 352 pgs., Smithsonian Institution Press, Washington, DC
  • 11623 - Savitzky, A. H., C. E. Peterson, 2001, Personal Communication, Expert Review for GAP Analysis Project, Old Dominion University

Click to view the 2011 DGIF Canebrake Rattlesnake Conservation Plan


Photos:

*Click on a thumbnail for a larger version.

Male Guarding
Males will often defend their mate from other males,
but we have never seen it to this extreme. This 5ft.
male is literally curled-up and sitting on the female.
You can barely see the edge of the 4ft. female under him.


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We have a large diversity of salamanders consisting of 56 different species and subspecies.

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