Rattlesnakes | Herps of Texas

Crotalus atrox

Mon, 01 Jan 0001 00:00:00 +0000

Scientific name. Crotalus atrox

Common Name. Western Diamond-backed Rattlesnake

General information. All rattlesnakes are venomous, and therefore potentially dangerous if approached or handled. Rattlesnakes are not generally aggressive and will most likely flee if given a chance to retreat. The western diamond-backed rattlesnake is primarily a nocturnal animal, hunting for its prey on warm summer nights. It is, however, seasonally diurnal, moving between hunting sites during the day during the cooler spring and fall months. The western diamond-backed rattlesnake is usually inactive between late October and early March, though an occasional rattlesnake may be seen sunning itself on warm winter days.

Protected status. The Western Diamond-backed Rattlesnake is not a protected species in Texas and can be legally collected with a hunting license.

Diagnostic features. Undivided anal scale Dorsal scales extremely keeled, often in rows of 25 to 27 near midbody

Coloration. Background coloration of tan or brown surrounds series of diamond-shaped blotches Dorsal coloration varies tremendously over its distributional range, though typically shades of tan or brown Tail is black and white banded (sometimes called “coontail” across its range) Ventral surface is off-white and usually unmarked.

General distribution. In the United States, Crotalus atrox is found in California, Arizona, New Mexico, Oklahoma and Texas. The Western Diamond-backed Rattlesnake also has an extensive range in the northern half of Mexico.

Texas distribution. In Texas, Crotalus atrox is found throughout the state, save the wettest eastern portions of the state. Its relative, the Eastern Diamond-backed Rattlesnake (Crotalus adamanteus), is found in eastern Louisiana and ranges from there through Florida to North Carolina.

Habitat. Found from the flatlands and prairies to the rocky hills and low mountains, the Western Diamond-backed Rattlesnake is in turn preyed upon by a variety of larger mammals and birds, such as coyotes, foxes, and hawks.

Reproduction. Mating occurs in the spring and the females give birth (they are viviparous) to as many as 25 young, which may be as long as 30 cm (12 in) in length. The young are fully capable of delivering a venomous bite hours after their birth.

Size. Adults typically measure between 0.91-1.21 m (3-4 ft) - this is the longest rattlesnake in Texas with the record length over 213 cm (84 in).

Map. Orange counties indicate new county records since previous Herps of Texas update in 1998; all other colored counties reflect known distribution prior to 1998 for species and/or subspecies. Map is based on museum voucher specimens.

Crotalus horridus

Mon, 01 Jan 0001 00:00:00 +0000

Scientific name. Crotalus horridus

Common Name. Timber Rattlesnake

General information. Like all rattlesnakes the Timber Rattlesnake is venomous, and therefore dangerous if disturbed. If encountered in the wild, they are better left alone. Feeding primarily on rodents and rabbits, the Timber Rattlesnake is a sit-and-wait predator, often found lying adjacent to rodent paths that weave through the vegetation. They may lie in wait for several days for the chance to capture a meal. Because timber rattlesnakes often congregate in large numbers at den sites for their winter hibernation, they are highly susceptible to human interference. In fact, many populations in the northeastern U.S. have been eliminated as a result of over-collection and unnecessary killing by humans. These snakes are an important part of the food web because they limit rodent populations, as well as being a source of food to several large mammal and bird species. Conservation efforts have been implemented in many states in an effort to learn more about these important predators and to protect those remaining populations from further human-induced problems

Protected status. The Timber Rattlesnake is the only protected species of venomous snake in Texas and can not be collected without a scientific collecting permit.

Diagnostic features. Undivided anal plate Keeled dorsal scale rows are either in rows of 25 or 27 near midbody

Coloration. Dark crossbands covering a gray background In some individuals, light cinnamon-colored vertebral stripe covers a portion of each crossband Background color may be a shade of yellow, or even darkly pigmented, obscuring the distinction between the blotches and the background Tail is black Belly is mostly white with areas of pigment found near the border between ventral and dorsal scales.

General distribution. The range of Crotalus horridus extends through much of the United States, including most of the states east of the Mississippi River. West of the Mississippi, the timber rattlesnake is found as far west as Nebraska, Kansas, Oklahoma and Texas, and as far north as Minnesota. It is not found in Mexico, and only a single small population is found in Canada.

Texas distribution. Crotalus horridus is found only in the wetter portions of the eastern quarter of the state.

Habitat. Timber Rattlesnakes can be found in the wooded forests, as well as the well-vegetated lowlands. In Texas, it can be found associated along heavily vegetated riparian waterways found in the eastern part of the state.

Reproduction. Females give live birth to an average of ten young in the late summer months. These young rattlesnakes may measure between 20-40 cm (8-16 in) at birth.

Size. Adults may reach to 152 cm (60 in) in length.

Crotalus lepidus

Mon, 01 Jan 0001 00:00:00 +0000

Scientific name. Crotalus lepidus

Common Name. Rock Rattlesnake

General information. Rattlesnakes are not generally aggressive and will leave the area if given a chance to retreat; but are all rattlesnakes are venomous and should be left alone. Primarily a nocturnal predator during the hot summer months, C. lepidus feeds on lizards and mice which live in cracks and crevices of the rocky hillsides. The heat-sensing pits are very useful when hunting a mouse through an underground tunnel system. In the spring and fall, the rock rattlesnake can be diurnal, moving between shelters and basking in the sunshine of the cooler mornings. During the winter, the rattlesnakes seek retreats deep in the crevices, away from the dangerously low outside temperatures.

Protected status. The Rock Rattlesnake is not a protected species in Texas and can be legally collected with a hunting license.

Diagnostic features. Undivided anal scale Dorsal scales extremely keeled, often in rows of 23 near midbody

Coloration. Typically grey in overall coloration, although certain populations may blend into their surrounding rocky habitat with dorsal colors of pink, brown and tan Series of crossbands run the length of the animal Pink or grey belly may or may not be pigmented.

General distribution. In the United States, Crotalus lepidus is found only in the rocky mountains and hills of southern Arizona, New Mexico, and Texas. The distributional range of C. lepidus includes two additional subspecies in Mexico, extending well into the interior of the country as far south as the mountains of Zacatecas.

Texas distribution. In Texas, Crotalus lepidus is found from El Paso County in the west, throughout Big Bend and much of the Trans-Pecos, to the eastern edges of the Hill Country in Bandera County.

Habitat. The small Rock Rattlesnake well deserves its common name as it spends its life in and around rocky outcrops and crevices found in the Trans-Pecos region of Texas.

Reproduction. Rock Rattlesnakes mate during the summer months, and actually overwinter while pregnant, giving live birth to litters of 2-8 young a year after mating. The young measure less than 20 cm in length at birth.

Size. Adults are rarely larger than 61 cm (24 in); record length is 76 cm (30 in).

Crotalus ornatus

Mon, 01 Jan 0001 00:00:00 +0000

Scientific name. Crotalus ornatus

Common Name. Eastern Black-tailed Rattlesnake

General information. Like all rattlesnakes, the Eastern Black-tailed Rattlesnake is venomous and should be left alone. Even though it is generally restricted to rocky habitats, C. ornatus can be found at a wide range of elevations up and down a hillside. blacktail rattlesnakes found along this large elevational gradient (1000-2500 m) can demonstrate extremes seen in background colorations. At lower elevations, the background colors of C. molossus are often gray or dusty brown, allowing the rattlesnake to blend in better with its sparsely vegetated and dry desert scrub surroundings. At higher elevations, such as the Davis Mountains in Jeff Davis County, the background colors are generally more yellowish, which contrast more strongly with the dark vertebral blotches and allow the rattlesnake to camouflage itself more effectively in the shadows created by the pinon-juniper woodland. The black-tailed rattlesnake is also thought to be one of the most passive rattlesnakes in the state, relying instead on its camouflage for protection against predators rather than using its attention-grabbing rattles to warn would-be attackers. The black-tailed rattlesnake eats a variety of vertebrate prey, feeding on mammals, birds and even lizards.

Protected status. The Eastern Black-tailed Rattlesnake is not a protected species in Texas and can be legally collected with a hunting license.

Diagnostic features. Undivided anal scale Dorsal scales extremely keeled, often in rows of 25-29 near midbody

Coloration. Background color can be extremely variable, ranging from yellowish tan or olive to gray or dark brown A series of very dark blotches are found down the back with the posteriormost blotches forming crossbands Top or crown of the head is often dark brown or black and contrasts with the tan or yellow coloration of the rest of the head Chocolate brown ocular stripe runs through the eye into the corner of the mouth All-black tail is striking, and the black velvet color begins immediately at the vent and covers the entire tail.

General distribution. In the United States, Crotalus ornatus is found in Arizona, New Mexico, and Texas.

Texas distribution. C. ornatus is mostly found throughout the rocky areas of the Trans-Pecos, but has also occurred historically eastward to the edges of the Edwards Plateau, including Bandera and Travis Counties.

Habitat. The heavy-bodied Eastern Black-tailed Rattlesnake is most frequently encountered in rough and rugged mountain canyons and hillsides, though it is sometimes found crossing the flatland separating rocky areas.

Reproduction. Gravid (or pregnant) C. ornatus give birth to live young in the late summer, generally in July and August, which coincides with the onset of the summer monsoons. The neonate Eastern Black-tailed Rattlesnake may number between 3 and 16, and average around 27 cm (10.5 in) in length.

Size. Adults may measure 76-110 cm (30-42 in); record length is 125 cm (49 in).

Crotalus scutulatus

Mon, 01 Jan 0001 00:00:00 +0000

Scientific name. Crotalus scutulatus

Common Name. Mohave Rattlesnake

General information. Crotalus scutulatus is a nocturnal hunter, feeding on small mammals and lizards. Although all rattlesnakes are venomous and worthy of great respect, this species is particularly dangerous. There are two types of venom found within the distribution of Mojave rattlesnakes. Venom type A, or “Mojave toxin,” is quite different than most rattlesnake venoms in that it is neurotoxic, and affects the respiratory and nervous systems of its prey. Venom type B is similar to most other U.S. rattlesnakes in being hemotoxic, effectively destroying tissue around the site of the bite. Venom type B appears to be prevalent in C. scutulatus found within the state of Texas, but snakes with a mixture of both types of venom have been found. Other populations of other species of rattlesnakes have also been found to have small percentages of Mojave toxin present in their venoms as well. Advanced medical treatments save the lives of the hundreds of people bitten by rattlesnakes each year, with much less than 1% of all bites resulting in fatalities. Most of these fatalities are the result of delays from seeking medical treatment.

Protected status. The Mohave Rattlesnake is not a protected species in Texas and can be legally collected with a hunting license.

Diagnostic features. Undivided anal scale Dorsal scales extremely keeled, often in rows of 25 near midbody

Coloration. Body is yellowish-tan to light brown above Occasionally individuals have an overall greenish tint to their background color, which has resulted in the name “Mohave greens.“Series of dark diamond blotches with light edges, similar to those of the western diamondback (see below), running along the length of the body Blotches flatten into bands near the tail Belly is slightly pigmented near the edges of the dorsal scales Tail is ringed by white and black bands, with white bands twice the width of black bands A series of light facial stripes also run in front of, and behind the eye, contrasting with the more darkly colored head.

General distribution. In the United States, Crotalus scutulatus is found in the southern portions of California, Arizona, New Mexico, and Texas. There are two subspecies of the Mohave Rattlesnake, though only one (C. s. scutulatus) is found in the U.S. The Mojave rattlesnake also has an extensive range in the northern half of Mexico.

Texas distribution. Crotalus scutulatus is restricted to the western edges of the state, from El Paso to the Big Bend.

Habitat. Found primarily in the flat deserts and semi-grasslands of the Trans Pecos region of extreme West Texas.

Reproduction. Crotalus scutulatus is viviparous, giving birth to live young in late July or August, often coinciding with the summer monsoons. There may be as many as nine young, measuring up to 25 cm (10 in) in length.

Size. Adults may measure 61-90 cm (24-36 in); record length is 129 cm (51 in).

Crotalus viridis

Mon, 01 Jan 0001 00:00:00 +0000

Scientific name. Crotalus viridis

Common Name. Prairie Rattlesnake

General information. Rattlesnakes are not generally aggressive and will likely flee if given a chance. They are of course poisonous, and should be treated with great respect. It is a nocturnal species when encountered in the Trans-Pecos region, though populations in the Panhandle may also be active in the early morning hours around dawn, as well as around dusk. In extreme northern U.S. populations, C. viridis may be entirely diurnal, because nightime temperatures often drop to cold extremes. In certain areas, the number of appropriate rocky crevices and caves for winter hibernation are limited. Because of these scarce sites, hibernation sites or dens are often shared by more than one animal during the winter. These dens may hold as many as twenty or so snakes when found in the Panhandle, whereas dens found in colder extremes of Wyoming and Colorado may contain hundreds of snakes. It is important to also note that it is not uncommon to find both venomous and non-venomous snakes sharing the same den site.

Protected status. The Prairie Rattlesnake is not a protected species in Texas and can be legally collected with a hunting license.

Diagnostic features. Undivided anal scale Dorsal scales extremely keeled, often in rows of 25-27 near midbody

Coloration. Body has overall dorsal color ranging from tan to light brown 35-55 contrasting dark brown oval vertebral blotches that run the length of the body Blotches flatten out into narrow crossbands on the tail An additional row of faint brown blotches can be seen laterally, though greatly obscured in many individuals Belly is off-white and is unpigmented Two light colored facial stripes, bordering both sides of a dark subocular stripe A series of light facial stripes also run in front of, and behind the eye, contrasting with the more darkly colored head; posteriormost light stripe does not extend into the corner of the mouth.

General distribution. In the United States, Crotalus viridis is found in New Mexico, Texas, Colorado, Oklahoma, Kansas, Wyoming, Montana, and both North and South Dakota. A few populations extend into portions of northern Mexico and southwestern Canada.

Texas distribution. C. viridis is found in the western portions of the state, from the Panhandle, to portions of the Trans-Pecos and the Stockton Plateau.

Habitat. Crotalus viridis is a prairie specialist (as indicated by its common name) and feeds upon many of the birds and mammals found in these grasslands; juvenile prairie rattlesnake will additionally feed on lizards.

Reproduction. Female prairie rattlesnakes give live birth to as many as 14 young, averaging 24 cm (9.5 in) in length, in August, September and October.

Size. Adults up to 91.5 cm (36 in); record length is more than 119 cm (47 in).