Hog-nosed Snakes | Herps of Texas

Heterodon kennerlyi

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

Scientific name. Heterodon kennerlyi

Common Name. Mexican Hog-nosed Snake

General information. Hog-nosed snakes are so named because of their upturned keeled rostral scale. This modification allows them to burrow easily into the soil, either to seek shelter or to seek out their prey. Mexican Hog-nosed Snakes are rear-fanged, that is they are venomous, though they pose little threat to humans, even when handled, because of this species reluctance to bite. Occasional bites to humans do occur, usually when a person has been handling toads prior to handling a hog-nosed snake. Human reactions to hog-nosed snake bites can include large amounts of swelling, depending on the duration of the bite. Their venom, though mild to human, is highly effective against its usual prey of frogs, toads, and occassionaly lizards. Young snakes may ingest crickets and other insects. The venom is delivered to the prey by way of enlarged teeth in the rear of the mouth through a chewing motion. Western hog-nosed snakes feed mainly on amphibians and lizards, though they will eat other snakes, small mammals, and occasional birds. Hog-nosed snakes are active in the morning and around dusk during the warmer parts of the year, burrowing in sandy soils during the winter.

Protected status. The Mexican Hog-nosed Snake is not a protected species in Texas.

Diagnostic features. Divided anal plate Keeled dorsal scales in rows of 23 at midbody Six or fewer azygous scales

Coloration. Dorsal ground color is light tan or buff, with a series of large, elliptical blotches down the spine A series of small brown spots also runs the length of the body on each side of the body. The number of azygous scales found behind the upturned rostral on the head can help distinguish this species from H. nasicus, with 9 or more in H. nasicus. The belly, especially the tail, is black, with patches of white or yellow present.

General distribution. Heterodon kennerlyi is found in Texas, New Mexico, and Arizona, and south into the northern states of Mexico.

Texas distribution. Heterodon kennerlyi is found in many counties of the Trans-Pecos and south Texas, following along the Rio Grande from El Paso to south Texas.

Habitat. Mexican Hog-nosed Snakes inhabit a wide variety of areas, but are most commonly found in areas with grasslands and sandy soils in the Trans-Pecos, and mesquite grassland and thorn-scrub habitats in south Texas.

Reproduction. Mexican Hog-nosed Snakes are egg-bearing, breeding in alternate years. Clutches range from 4-23 eggs, and are laid in the summer months. Incubation is about two months with hatchlings measuring 15-19 cm (6-7.5 in) in length.

Size. Adult Heterodon kennerlyi are typically 38-63.5 cm (15-25 in) in length, though this is one of smallest species of hog-nosed snakes.

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.

Heterodon nasicus

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

Scientific name. Heterodon nasicus

Common Name. Plains Hog-nosed Snake

General information. Hog-nosed snakes are so named because of their upturned keeled rostral scale. This modification allows them to burrow easily into the soil, either to seek shelter or to seek out their prey. Plains Hog-nosed Snakes are rear-fanged, that is they are venomous, though they pose little threat to humans, even when handled, because of this species reluctance to bite. Occasional bites to humans do occur, usually when a person has been handling toads prior to handling a hog-nosed snake. Human reactions to hog-nosed snake bites can include large amounts of swelling, depending on the duration of the bite. Their venom, though mild to human, is highly effective against its usual prey of frogs, toads, and occassionaly lizards. Young snakes may ingest crickets and other insects. The venom is delivered to the prey by way of enlarged teeth in the rear of the mouth through a chewing motion. Western hog-nosed snakes feed mainly on amphibians and lizards, though they will eat other snakes, small mammals, and occasional birds. Hog-nosed snakes are active in the morning and around dusk during the warmer parts of the year, burrowing in sandy soils during the winter.

Protected status. The Plains Hog-nosed Snake is not a protected species in Texas and can be legally collected with a hunting license.

Diagnostic features. Divided anal plate Keeled dorsal scales in rows of 23 at midbody Nine or more azygous scales

Coloration. Dorsal ground color is light tan or buff, with a series of large, elliptical blotches down the spine A series of small brown spots also runs the length of the body on each side of the body. The number of azygous scales found behind the upturned rostral on the head can help distinguish this species from H. kennerlyi, with 6 or fewer in H. kennerlyi. The belly, especially the tail, is black, with patches of white or yellow present.

General distribution. Heterodon nasicus is found from Alberta, Canada, through the midwest and plains sections of the U.S., into Texas and portions of northern and central Mexico.

Texas distribution. In Texas, Heterodon nasicus can be found throughout many areas of the state, though they are largely absent from the Edwards Plateau and far east Texas, as well as the Rio Grande Valley.

Habitat. Plains Hog-nosed Snakes inhabit a wide variety of areas, including but not limited to flat grasslands, rocky arid lands and coastal barrier islands.

Reproduction. Plains Hog-nosed Snakes are egg-bearing, breeding in alternate years. Clutches range from 4-23 eggs, and are laid in the summer months. Incubation is about two months with hatchlings measuring 15-19 cm (6-7.5 in) in length.

Size. Adult Heterodon nasicus are typically 38-63.5 cm (15-25 in) in length.

Heterodon platirhinos

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

Scientific name. Heterodon platirhinos

Common Name. Eastern Hog-nosed Snake

General information. Hog-nosed snakes are so named because of their upturned keeled rostral scale. This modification allows them to burrow easily into the soil, either to seek shelter or to seek out their prey. Eastern Hog-nosed Snakes are rear-fanged, that is they are venomous, though they pose little threat to humans, even when handled, because of this species reluctance to bite. Occasional bites to humans do occur, usually when a person has been handling toads prior to handling a hog-nosed snake. Human reactions to hog-nosed snake bites can include large amounts of swelling, depending on the duration of the bite. Their venom, though mild to human, is highly effective against its usual prey of frogs, toads, and occasionaly lizards. Young snakes may ingest crickets and other insects. The venom is delivered to the prey by way of enlarged teeth in the rear of the mouth.

Protected status. The Eastern Hog-nosed Snake is not a protected species in Texas and can be legally collected with a hunting license.

Diagnostic features. Anal plate is divided Dorsal scales are keeled, in rows of 23 or 25 at midbody

Coloration. Wide variety of background dorsal color, ranging from tan, brown, and olive to yellow and orange. Some individuals, especially those along the eastern coast of the U.S., are entirely black (or melanistic) A series of darker blotches running the length of the body along the spine, with dark blotches present on either side of the neck and a series of small circles running the length of the body on each side of the body. A postocular stripe and a dark bar between the eyes is also present The belly is gray and unmarked with dark pigment, with the underside of the tail often lighter than the dorsal color of the body.

General distribution. Heterodon platirhinos is confined to the eastern half of the U.S., found from New Hampshire and Cape Cod, south to Florida, west to Texas and north to Minnesota.

Texas distribution. In Texas, H. platirhinos is found in the eastern two thirds of the state including the Panhandle, but excluding parts of South Texas.

Habitat. Eastern Hog-nosed Snakes are associated with grassy areas or riparian watercourses where loose soil is available for burrowing. Eastern hog-nosed snakes are often seen in areas along streams or lakes, sometimes associated with open woodlands or pine forests.

Reproduction. Breeding occurs in the spring with eggs laid around a month and a half after mating. Clutch size range from 4-61 (average of 22) eggs, hatching in late summer. Newborn hatchlings are 16.5-24 cm (6.5-9.5 in).

Size. Adult Eastern Hog-nosed Snakes reach 51-84 cm (20-33 in) in length.