Reptiles of North Carolina

Scientific Name:	Common Name:		Family (Alpha):

NC Records
COLUBRIDAE Members:
Heterodon platirhinos - Eastern Hog-nosed Snake

Photo: E. Conway, N. Williamson, M. Prinz

Photo: Steve Hall

Photo: J. Schimel, J. Davis, T. Taylor

Photo: Jim Petranka and Bill Booth

Taxonomy

Class: Reptilia

Order: Serpentes

Family: COLUBRIDAE

Subfamily: Dipsadinae

Other Common Name(s): Eastern Hognose Snake


Taxonomic Comments: Heterodon consists of four species of small to medium-sized dipsadine snakes native eastern and central North America, from southern Canada to northern Mexico.
Species Comments: Heterodon platirhinos, the Eastern Hog-nosed Snake, is one of two Heterodon in North Carolina. This species is found across the eastern and central United States, from New England south to Florida, and west to Texas, Kansas, and Nebraska. In North Carolina it is likely found state-wide, though records are lacking for some of the Mountain counties. No subspecies are recognized. This species was originally described by Linneaus in 1766 as "Coluber simus", but this name became mistakenly associated with the Southern Hog-nosed Snake (now H. simus). Given the long usage of the name "Heterodon platirhinos", the ICZN suspended the law of priority in favor of taxonomic stability, selecting the next oldest available name (described by Latreille in 1801). The correct spelling of the specific epithet is "platirhinos" rather than a "platyrhinos", as is occasionally used; see Edgren (1953) and Platt (1985) for more information. The generic epithet Heterodon is derived from the Greek heteros, "different", and odon, "tooth", in reference to their enlarged posterior teeth. The specific epithet platirhinos is from the Greek platys, "broad" or "flat", and rhinos, "snout", in reference to their distinctive upturned rostral scale. Taxonomic References: Blem (1981); Platt (1985).

Identification

Description: Eastern Hog-nosed Snakes are medium-sized snakes with stout bodies and a distinctive upturned snout. Their coloration can be highly variable. Their dorsum may be some combination of brown, tan, yellow, gray, or red, with dark black body blotches and tail bands; some individuals are entirely black or entirely dark gray with no pattern. Per Palmer and Braswell (1995), this melanistic phenotype is acquired with age, and is more common on the Coastal Plain, and decreases towards the Mountains. The venter is often stippled or mottled black and gray, though the underside of the tail may be lighter than the rest of the venter. Patterned individuals often have a large "V"-shaped marking on the back of the head, as well as a dark stripe that crosses between the eyes and down to the base of posterior-most supralabial.

Morphological Features: Eastern Hog-nosed Snakes have 23-25 keeled midbody scale rows. Ventral counts range from 112-154 (121-146 in NC specimens; Palmer and Braswell, 1995), with 30-64 (37-60) subcaudals and a divided anal plate. Head scale counts are typically as follows: 8 supralabials, 10-11 infralabials, 1 loreal, 2 nasals, and 3-4+4-5 temporals. Additionally, a ring of 8-13 ocular scales are arranged in a ring around the eye, and additional azygous scales may separate the prefrontals from the internasals. Palmer and Braswell (1995) noted variation in scalation across multiple specimens in NC.

Eastern Hog-nosed Snakes have a maximum recorded total length of 115.6 cm (45.5 inches). Palmer and Braswell (1995) reported a 112.5 cm female specimen from NC. Tail lengths account for approximately 15-23% of total length. Females reach larger sizes than males; males have longer tails, more subcaudals and tail bands, and fewer ventrals and body blotches.

Eastern Hog-nosed Snakes have distinctly enlarged posterior teeth and Duvernoy's glands, and their secretions do produced mildly toxic effects in some people, which may include swelling and burning pain (see Grogan, 1974; McKinstry, 1978; Young, 1992). Some care should be taken when handling them, though broadly these snakes are not dangerous to humans or pets. Typically, this species does not bite, but instead will flair out its neck and hiss loudly, then famously death-feign by flipping over, gaping their mouths, and excreting waste.

Technical Reference: Palmer and Braswell (1995); Ernst and Ernst (2003).

Field Guide Descriptions: Palmer and Braswell (1995); Ernst and Ernst (2003); Beane et al. (2010).

Online Photos: Google iNaturalist GBIF

Observation Methods: Eastern Hog-nosed Snakes may be found out in the open during the day, or under cover. Some may burrow in small mammal mounds, and others are encountered while crossing roads.

Distribution in North Carolina

County Map: Clicking on a county returns the records for the species in that county.

Key Habitat Requirements

Habitat: Eastern Hog-nose Snakes occur in both forests and fields, usually those that have sandy or loose soils and rarely in those that frequently flooded (Palmer and Braswell, 1995; Beane et al., 2010).

Biotic Relationships: Eastern Hog-nosed Snakes primarily consume toads (Anaxyrus), and other amphibians including spadefoot toads, true frogs, tree frogs, and salamanders (including ambystomatids, plethodontids, and newts) are often recorded. Additionally, they are known to consume various invertebrates, small mammals (including mice, voles, and shrews), and occasionally reptiles such as skinks, fence lizards, and small snakes (Platt, 1969; Brown, 1979; Palmer and Braswell, 1995; Ernst and Ernst, 2003). As noted by Platt (1969), some reports of invertebrates in stomach contents are likely the result of secondary ingestion via anuran prey.

Documented predators of Eastern Hog-nosed Snakes include ophiophagous snakes (including racers and coachwhips, kingsnakes, rat snakes, cottonmouths, and coralsnakes) and birds (including hawks, crows, and owls), and juveniles may fall prey to large tarantulas (Ernst and Ernst, 2003).

Life History and Autecology

Breeding and Courtship: Sexual maturity occurs at approximately 50 cm total body length. Mating occurs in the spring (primarily April and May), and a second breeding period may occur in Fall (September and October, per Ernst and Ernst, 2003).

Reproductive Mode: Eastern Hog-nosed Snakes are oviparous and typically lay large clutches of eggs in summer (June to July) that hatch in later summer or early Fall (August to September). Clutches average 23–25 cream white, elongate eggs approximately 30 mm long.

Hatchlings are approximately 20–24 cm in total length and weigh approximately 5 g after shedding their natal skin (Palmer and Braswell, 1995).

Terrestrial Life History: Eastern Hog-nosed Snakes are most common in forested and edge habitats with porous soil. They are diurnal, but when not actively foraging or looking for a mate is semi-fossorial, spending time burrowed in loose soil or under cover. They have been recorded in every month in North Carolina, but most activity occurs in the spring and then fall; most records are from April to June and September. During colder months they may hibernate underground by burrowing (or using a mammal burrow), or within rotting logs.

Numerous home range studies have been carried out on Eastern Hog-nosed Snakes across their range, but none on populations in North Carolina. Home range estimates vary; in Arkansas and New Hampshire they averaged approximately 50 hectares (500,000 m²; Plummer and Mills, 2000; Lagory et al., 2010), while in New York they averaged only 24 ha (Vanek and Wasko, 2017).

General Ecology

Adverse Environmental Impacts

Status in North Carolina

NHP State Rank: S4S5

Global Rank: G5

Photo Gallery for Heterodon platirhinos - Eastern Hog-nosed Snake		84 photos are available. Only the most recent 30 are shown.
	Recorded by: J. Buie Stokes Co. Comment:	Recorded by: B. Rossi Stokes Co. Comment:
	Recorded by: A.Whitsle Stokes Co. Comment:	Recorded by: michael wilson Harnett Co. Comment:
	Recorded by: K. Sanford Gates Co. Comment:	Recorded by: E. Conway, N. Williamson, M. Prinz Moore Co. Comment:
	Recorded by: E.Conway Moore Co. Comment:	Recorded by: R. Evans Onslow Co. Comment:
	Recorded by: Z. Lunn, D. Crilley, J. Baxley Robeson Co. Comment:	Recorded by: T. Stafford Moore Co. Comment:
	Recorded by: V. Jones Iredell Co. Comment:	Recorded by: E. Helms, C. Helms New Hanover Co. Comment:
	Recorded by: C. Blake Washington Co. Comment:	Recorded by: S.Coffman, J.Barnes Dare Co. Comment:
	Recorded by: T. Stafford Moore Co. Comment:	Recorded by: C. Bennett, W. Ruark Iredell Co. Comment:
	Recorded by: J. Fields Cumberland Co. Comment:	Recorded by: Privette Bladen Co. Comment:
	Recorded by: C. Bennett Dare Co. Comment:	Recorded by: J. Summers, M. Walker Harnett Co. Comment:
	Recorded by: J. Summers, D. Brown Harnett Co. Comment:	Recorded by: M. Gosselin Dare Co. Comment:
	Recorded by: M. Gosselin Dare Co. Comment:	Recorded by: K. Bischof Burke Co. Comment:
	Recorded by: M. Gosselin Dare Co. Comment:	Recorded by: M. Gosselin Dare Co. Comment:
	Recorded by: M. Gosselin Dare Co. Comment:	Recorded by: M. Gosselin Dare Co. Comment:
	Recorded by: M. Gosselin Dare Co. Comment:	Recorded by: M. Gosselin Dare Co. Comment:

Heterodon platirhinos - Eastern Hog-nosed Snake

Photo Gallery for Heterodon platirhinos - Eastern Hog-nosed Snake

84 photos are available. Only the most recent 30 are shown.