Eastern Hog-nosed Snake
Heterodon platirhinos

** Harmless **

  • Eastern Hog-nosed Snake Melanistic
  • Eastern Hog-nosed Snake
  • Eastern Hog-nosed Snake
  • Eastern Hog-nosed Snake - Campbell Co.
Eastern Hog-nosed Snake Melanistic1 Eastern Hog-nosed Snake 2 Eastern Hog-nosed Snake 3 Eastern Hog-nosed Snake - Campbell Co.4

Common Name: Eastern Hog-nosed Snake
Scientific Name: Heterodon platirhinos
Etymology:
Genus: Heterodon is derived from the Greek words heteros meaning "different" and odon meaning "tooth".
 Species: platirhinos is derived from the Greek words platys meaning "broad or flat" and rhinos meaning "snout".
Vernacular Names: Adder, bastard rattlesnake, black adder, black blowing viper, black hog-nosed snake, black viper snake, blauser, blower, blowing adder, blowing snake, blowing viper, buckwheat-nose snake, calico snake, checkered adder, chuck head, common spreading adder, deaf adder, flat-head, flat-headed adder, hissing snake, hissing viper, mountain moccasin, poison viper, puff adder, red snake, rock adder, sand adder, sand viper, spotted viper, spread-head moccasin, spread-head snake, spread-head viper.
Average Length: 20 - 33 in. (51 - 84 cm)
Virginia Record Length:  44.5 in. (113 cm)
Record length: 45.5 in. (115.6 cm)
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: This species is from 18-30 inches long. The general coloration is variable and yellow, brown, gray, orange, or red may predominate. They are normally spotted, but jet-black or plain gray may occur in some areas. The belly is mottled, gray or greenish on yellow, light gray, or pinkish. The underside of the tail is lighter than the belly, and the scales are keeled *882*. In some localities, this species is referred to as a banana snake or as a banana viper *11523*. The longevity record of this species is 9 years and 2 months *11523*. Outside Virginia, the maximum known length is 45.5 inches *11523*. In Virginia, max known SVL is 955 mm (37.6 in.) and total length is 1130 mm (44.5 in.). Tail length/total length ratio is 12.2-24.0 (avg. = 18.5+/-6.1, n=60). Scutellation: ventrals 118-146 (avg. 130.5+/-6.2, n=98); subcaudals 37-64 (avg. 48.5+/-4,\.5, n=92); ventrals + subcaudals 163-200 (avg. = 178.5+/-6.0, n=91); dorsal scales keeled; scale rows usually 25 (76.3%, n=59) at midbody, 21-24 (23.7%); anal plate divided; infralabials 10-10 (35.9%, n=64), combinations of 9-11 (60.9%), combinations of 10-12 (3.1%); supralabials 8-8 (88.5%, n=61), other combinations of 7-9 (11.5%); rostral scale upturned with a posterior keel; single azygous scale present separating nasal scales; loreal present; no preocular or postocular scales; ocular ring scales 10-10 (29.4%, n=34), other combinations of 8-12 (70.6%); temporals usually 3+4/3+4 (57.7%, n=52), other combinations of 2-5 (42.3%).

COLORATION and PATTERN: Two color phases are common in Virginia; (1) patterned phase (79.6%, n=98), characterized by a series of 19-27 (avg. = 23.2+/-2.4, n=12) black or dark brown blotches along the middorsal line, with alternating black spots on the sides; body color consists of varying combinations of gray, tan, pink, yellow, orange, and red; venter of body and tail immaculate cream to dark gray; in some snakes, anterior portion of venter is cream but black to gray pigment increases in concentration posteriorly; tail may be light in color while rest of the venter is dark; chin and supralabials white; a black stripe between eye and posterior margin of the mouth occurs on some individuals; black crossbar lies in front of the eyes; two dark, broad patches on side of neck; (2) melanistic phase (20.4%, n=98), characterized by uniform black coloration dorsally, usually without evidence of a pattern; venter of body and tail on these snakes may be cream peppered with black or all drk gray; in some, venter of the tail is cream and venter of the body is dark gray; some melanistic individuals are grayish and varying degrees of the dark blotch pattern. The posterior tooth on each of the maxillary bones is enlarged.*10760*

SEXUAL DIMORPHISM: Sexual dimorphism is expressed in scutellation, body proportions , and number of dorsal blotches. Average adult SVL in males is less (518.8+/-119.1, 315-880, n=34) than in adult females (644.5+/-118.9, n=523-955). Sexual dimorphism index is 1.24. Males have proportionally longer tails (tail length/total length ratio 14.8-24.0, avg. = 19.3+/-6.9, n=37) than females (12.2-21.0, avg. = 15.4+/-2.1, n=22). Males have fewer average number of ventrals (avg. = 127.3+/-4.7, 118-141, n=61) but more subcaudal scales (avg. = 50.1+/-3.9, 41-60, n=59) than females (ventrals avg. = 136.2+/-4.0, 126-146, n=34; subcaudals avg. = 45.8+/-5.0, 37-64, n=30). Average number of ventrals + subcaudals (males 177.2+/-5.6, 163-190, n=59; females 181.6+/-6.0, 172-200, n=29) and average number of dorsal body blotches (males 22.8+/-2.5, 19-27, n=12; females 22.9+/-2.5, 20-25, n=8) are similar between sexes. Scott (1986) found that female H. platirhinos (n=28) from the Va. portion of Assateague Island were significantly longer (males 442+/-18 mm SVL, females 544+/-27 mm SVL), heavier (males 94.9+/-9.6 g; females 140.6+/-14.5 g), and had more dorsal blotches (males 21.8+/-0.3, females 23.7+/-0.4) than males (n=38). Mainland Virginia females are heavier (avg. = 198.5+/-133.5 g, 72-429, n=6) than males (avg. = 113.0+/-40.4 g, 60-170, n=6).*10760*

JUVENILES: All juveniles examined (n=23) exhibited a patterns found in adults, except that a pinkish coloration was more prominant upturned rostral scale. Hatchling H. platirhinos are chunky with the prominant upturned rostral scale. Hatchling size in Virginia is unknown. Ernst and Barbour noted that they are 168-250 mm in total length.*10760* Confusing species: This species is usually not confused with any other snake because of its behavior when found in the field. No other Virginia species possesses the upturned rostral scale or exhibits similar antipredator behaviors. Copperheads (Agkistrodon contortrix) has a series of brown hourglass-shaped crossbands on the dorsum.*10760*

GEOGRAPHIC VARIATION: There is no geographic variation in number of blotches or counts of scales characters among physiographic regions in Virginia that cannot be explained by the small regional sample sizes.*10760*

REPRODUCTION: This species will emerge from hibernation in late March or early April and mate shortly thereafter. The eggs, range in size from .5-1.0 inches x 1.0-1.5 inches are laid in June or July and hatch in late July, August, or early September *1008*. There are 4-60 eggs/clutch *1014*. The young are 6.5- 8.0 inches at hatching *882*. Eggs are laid in sandy soil*10760*

BEHAVIOR: This species begins hibernation in late October or early November *1008*. When approached, it hisses, spreads the head to bluff, then plays possum, by rolling on its back, with its mouth open *882*. This species is diurnal, and crepuscular in the late spring and fall *2072*. The home range is slightly less than 1 per acre *2072*. Hognose snakes are docile animals that bluff and feign death to discourage potential predation against them. At the initial encounter, the snake will inflate his body and neck, coil with head elevated and often turned sideways, hiss by rapidly expelling air from the lungs, and strike with mouth open or closed. They will not bite. If this does not deter the predator and if the snake is touched, it will writhe as if in pain and agony, turn over repeatedly, open the mouth, extrude the tongue, and evert the cloaca. The mouth and cloaca often accumulate dirt or sand. After a minute or so of this behavior, the snake will lie on its back and become completely limp, as if dead. It will remain limp if it is picked up, but will roll over on its back if placed on its venter, as though all good dead snakes have to lie on their backs. If left unmolested for a few minutes, the snake will look to see if the predator is still around, and if the coast is clear, turn over and crawl away. The bluffing behavior has awarded it a plethora of vernacular names.*10760* When hognose snakes feign death, if the snake continues to be harassed after rolling over, the snake will eventually regurgitate any food item and it will defecate *11523*. This is an abundant snake in some areas, but the density depends on the amount of suitable habitat. Scott determined a population density of 4.8 snakes per hectare on southern Assateague Island. Clifford found that this species was the third most abundant snake in Amelia Co. However, Martin recorded only 17 hognose snakes of 545 snakes found in the Blue Ridge Mtns. in a 3 year period. On Assateague Island, the sex ratio was 1.1, distance moved between captures was 40-760 m (avg. = 390), juveniles growth was 2.2 cm per month, and growth of an adult male was 1.0 cm per month.*10760* An instance of an accidental bite by this species reported by Grogan resulted in mild envenomation to the victim while he was handling the snake. The hognose snake was feigning death. The writhing snake, with its mouth open, caught its teeth on the victim's arm. The symptoms were swelling, pain similar to a strong bee sting, dark purple discoloration around the wound changing to redness and nausea. Although H. platirhinos is not considered venomous, the saliva is apparently toxic to some people. Caution should be exercised when handling this snake.*10760*

ORIGIN: Native

References for Life History


Virginia Fish and Wildlife Information Service: Species Booklet

Photos:

*Click on a thumbnail for a larger version.

Short movie of an eastern hognose snake displaying  defensive behavior Melanistic Eastern Hog-nosed Snake displaying defensive behavior
Campbell Co. Melanistic Adult
Campbell Co.
     
        Eastern hog-nosed
snake eating a toad
Campbell Co.
Campbell Co. Fluvanna Co.
             
Melanistic Eastern Hog-nosed Snake Displaying Defensive Behavior
 

 

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