Eastern hog-nosed snake

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Eastern hognose snake
Southern Georgia morph
Scientific classification Edit this classification
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Order: Squamata
Suborder: Serpentes
Family: Colubridae
Genus: Heterodon
Species:
H. platirhinos
Binomial name
Heterodon platirhinos
Synonyms[3]
List

The eastern hog-nosed snake[4] (Heterodon platirhinos) is a species of mildly venomous rear-fanged snake in the family Colubridae. The venom is specifically adapted to amphibian prey and is harmless to humans. However, some people may have an allergic reaction and as a result experience local swelling and other symptoms. The species is endemic to North America.[5] There are no subspecies that are recognized as being valid.[4] This species prefers habitats with sandy soils and a combination of grass fields and forest edges.[6] It comes in many different colorations and has the identifiable upturned "snout".[7] It can be found in captivity, but is a relatively difficult species to keep due to a specialized diet of toads. As with other Heterodon species, it has a distinctive threat reaction of first bluffing by striking with a closed mouth and then, if this fails to deter the threat, pretending to die.

Geographic distribution

Heterodon platirhinos has a wide geographical range from the central United States to the East Coast. In the northern parts of its range, it can be found in southern Ontario, southern New Hampshire, Minnesota, Wisconsin, and Massachusetts.[8] Farther west, the snake can be found in Texas and Kansas. The southern part of its range extends into southern Florida.[9] Populations start to dwindle as the species reaches the northern limit of its range.[10]

Habitat

The preferred habitats of Heterodon platirhinos are upland sandy pine forests, old fields, and forest edges.[11] Like most of the genus Heterodon, it prefers dry conditions with loose soil for burrowing.[12] These loose soils are preferable habitat components for nesting and egg laying.[13] Barrier beach and dune ecosystems appear to contain some of the highest densities of H. platirhinos because of abundant prey (primarily anurans of the genus Anaxyrus).[14] At the northern end of its range, it has been found to prefer developed lands as its desired habitat, followed by mixed forests dominated by hemlock trees, pitch pines, or oaks.[15][8] In Canada, the average home range size is about 40 hectares (99 acres).[11] Its habitats include southeastern and midwestern woodlands, tall-grassland prairies, and grassy or cultivated fields along woodland edges.[16][7] Its habitat range tends to increase with grass and leaf litter.[17]

Etymology

North Carolina specimen
Florida specimen
Closeup of the head of H. platirhinos
Cape Cod, Massachusetts, specimen
H. platirhinos playing dead

The generic name Heterodon is derived from the Greek words heteros meaning "different" and odon meaning "tooth". The specific name platirhinos is derived from the Greek words platys meaning "broad or flat" and rhinos meaning "snout".[18]

Description

Heterodon platyrhinos is described as being quite stout-bodied.[19] Its color pattern is extremely variable, from red, green, or orange to brown, gray, or black, or any combination thereof depending on locality. Dorsally, it can be blotched, checkered, or patternless. The belly tends to be a solid gray, yellow, or cream-colored. In this species, the underside of the tail is lighter than the belly.[20] Its most distinguishing feature is the upturned snout, used for digging in sandy soils.[7] The average adult of H. platirhinos measures 71 cm (28 in) in total length (tail included), with females being larger than males. The maximum recorded total length is 116 cm (46 in).[21]

Behavior

The eastern hognose is a diurnal species.[7] It occurs in low densities, preferring to remain cryptic.[8] It is typically most active during April–September after coming out of hibernation. Because it has such a wide range, the snake is found there is variation in the population's climates which can cause the period of activity to change. In northern climates, hibernation comes earlier and begins late September–October whereas in southern climates, the snake might not retreat until November. There have been some recorded to still be active between December–February in Florida and along the Gulf Coast.[6] If the temperature reaches or drops below 19 degrees Celsius, hibernation will begin for the snake. This hibernation period takes place alone in burrows either dug by the snake or already made mammal burrows. To burrow, a snake forces its head into the soil then moves its head back and forth. For hibernation, these burrows will reach depths of 25 centimeters or more.[7]

Defensive behavior

When the eastern hognose snake is threatened, its neck is flattened and the head is raised off the ground, like a cobra. It also hisses and may strike with its mouth closed, but it does not attempt to bite— a behavior known as "bluffing".[22] The result can be likened to a high speed head-butt. If this threat display does not work to deter a would-be predator, an eastern hognose snake will often roll onto its back and play dead, going so far as to emit a foul musk from its cloaca and let its tongue hang out of its mouth.[20][23][24] One individual was observed playing dead for 45 minutes before reanimating and moving away.[25] This death-feigning behavior was also observed often in water habitats.[26] The duration and likelihood of death-feigning behavior in hognose snakes can vary depending on both intrinsic factors (such as individual condition) and extrinsic factors (such as predator type or environmental context).[27]

Diet

The eastern hognose snake preys extensively on amphibians and has a particular fondness for toads. This snake has resistance to the toxins toads secrete. This immunity is thought to come from enlarged adrenal glands, which secrete large amounts of hormones to counteract the toads' powerful skin poisons. At the rear of each upper jaw, it has enlarged teeth, which are neither hollow nor grooved, with which it punctures and deflates toads to be able to swallow them whole.[21][23][28] It also consumes other amphibians, such as frogs and salamanders. Like all other snakes, it eats its prey whole.[22] Because it is a toad-feeding specialist, its venom is adapted to be effective against toads and has not been found to be harmful to humans.[29]

Reproduction

Eastern hognose snakes mate in early April and May. Both the male and female snakes are known to have multiple mates during this season. The act of copulation can last for up to 3 days.[13] Occasionally, a second breeding period occurs around September and October. Rather than fertilizing a new egg clutch at this time, females instead store sperm until the spring for use.[7] Males follow the pheromone trails left behind by females on the move.[7][6] Some females have been observed traveling past viable nesting conditions to reach communal nesting sites.[30] Eggs might be laid in small soil depressions, mammal burrows, or under rocks, depending on the region.[13] The female may even dig the burrow herself, often choosing open and grassy areas with few herbs or shrubs because these areas get more sunlight, providing the warm temperatures needed for the proper development of the eggs.[31] The females, which lay up to 40 eggs (average about 25) in June or early July. The eggs, which measure about 33 mm × 23 mm (1+1⁄3 in × 1 in), hatch after about 60 days, from late July to September. The hatchlings are about 16.5–21.0 cm (6.5–8.3 in) long.[24] They have an average nest temperature of 23–26 °C (73–79 °F) incubating for an average of 49–63 days.[13] Some parental care is shown by the female such as nest and young guarding through hissing and chasing.[13] Typically, males reach maturity around 40 cm (16 in) in snout–vent length *SVL), which can take up to 18-24 months. Females, however, reach maturity around 45 cm (18 in) SVL, taking up to 21 months.[7][6]

Venom

Heterodon platirhinos is a mildly venomous species, but the effects are not deadly to humans.[16] Heterodon means "different tooth", which refers to the enlarged teeth at the rear of the upper jaw. These teeth inject a mild amphibian-specific venom into prey. The fangs receive the venom from the snake's Duvernoy's gland.[32] Bitten humans who are allergic to the saliva have been known to experience local swelling, burning, discoloration, and bleeding from the wounds, but no human deaths have been documented.[6]

Predators

The many predators of the eastern hognose snake include tarantulas, common kingsnakes, cottonmouths, crows, red-tailed hawks, barred owls, raccoons, Virginia opossums, red foxes, and humans.[7][6]

Human impact

Humans cause mortality of Heterodon platyrhinos from pollution and pesticide poisoning, habitat destruction, vehicular deaths, and intentional hunting.[7][6] Eastern hognose snakes avoid crossing paved roads, increasing the isolation of populations. The snakes will cross unpaved roads, but face higher mortality from vehicle collisions.[33]

Captivity

The hognose snake is an intermediate-level reptile to keep and lives between 10 and 15 years in captivity. Typically, mice and rats are used to feed most snakes in captivity. With this species being a toad specialist, getting them to eat thawed mice can be problematic. Scenting the food with toad or lizard is a trick used by hobbyists to entice the snake. Being a solitary species, snakes are kept individually unless kept for intentional breeding. Due to its burrowing nature, the hognose snake requires suitable substrate depth to retain this natural instinct.[34]

Conservation status

This species, Heterodon platirhinos, is classified as least concern on the IUCN Red List of Threatened Species (assessed in 2007).[35] It is a species of increasing conservation concern, though, especially in the northeastern part of its range.[36][37][38][39] Of the five states in the northeast U.S. where the eastern hognose snake occurs, it currently has "listed" conservation status in four (Connecticut, New Hampshire, New York, and Rhode Island).[40] Noted declines are believed to be the result of direct anthropogenic pressures, including habitat loss and fragmentation, road mortality, environmental degradation, and intentional killing.[6][41] Some of this habitat fragmentation may be due to the snake's having a reluctance to cross paved roads.[33] In the Eastern United States, pitch pine-scrub oak barrens are an imperiled disturbance-dependent community that has declined substantially due to wildfires that have threatened vertebrates such as the eastern hognose snake.[42]

References

  1. Hammerson, G.A. (2007). "Heterodon platirhinos". IUCN Red List of Threatened Species. 2007 e.T63820A12718733. doi:10.2305/IUCN.UK.2007.RLTS.T63820A12718733.en. Retrieved 19 November 2021.
  2. "Heterodon platirhinos Latreille, 1801". Global Biodiversity Information Facility. Retrieved 26 March 2025.
  3. Heterodon platirhinos at the Reptarium.cz Reptile Database. Accessed 14 September 2007.
  4. "Heterodon platirhinos". Integrated Taxonomic Information System. Retrieved 14 September 2007.
  5. McCoy, C.J., Jr., and A.V. Bianculli (1966). "The distribution and dispersal of Heterodon platyrhinos in Pennsylvania". Journal of the Ohio Herpetological Society 5 (4): 153-158.
  6. Ernst, Carl H.; Ernst, Evelyn M. (2003). Snakes of the United States and Canada. Smithsonian Books. pp. 146–150. ISBN 1-58834-019-8.
  7. Jessee, Renee. "Heterodon platirhinos (Eastern Hognose Snake)". Animal Diversity Web. Retrieved 2023-10-18.
  8. Buchanan, Scott W.; Timm, Brad C.; Cook, Robert P.; Couse, Richard; Hazard, Lisa C. (2017). "Spatial ecology and habitat selection of eastern hognose snakes". The Journal of Wildlife Management. 81 (3): 509–520. doi:10.1002/jwmg.21218. ISSN 1937-2817.
  9. Behler, J.L.; King, F.W. (1979). "Heterodon platyrhinos". The Audubon Society Field Guide to North American Reptiles and Amphibians. New York: Alfred A. Knopf. p. 744.
  10. Vanek, John P.; Wasko, Dennis K. (2017). "Spatial Ecology of the Eastern Hog-Nosed Snake (Heterodon platirhinos) at the Northeastern Limit of Its Range". Herpetological Conservation and Biology. 12 (1): 109–118.
  11. Robson, Laura Elizabeth (2011). The spatial ecology of Eastern Hognose Snakes (Heterodon platirhinos): habitat selection, home range size, and the effect of roads on movement patterns (Thesis). University of Ottawa. ProQuest 1355765570 64 pp.
  12. Scott, David (1986). "Notes on the Eastern Hognose Snake, Heterodon platyrhinos Latreille (Squamata: Colubridae), on a Virginia Barrier Island" (PDF). Brimleyana (12): 51–55.
  13. Cunnington, Glenn M.; Cebek, Joseph E. (2005). "Mating and nesting behavior of the eastern hognose snake (Heterodon platirhinos) in the northern portion of its range". The American Midland Naturalist. 154 (2): 474–478. doi:10.1674/0003-0031(2005)154[0474:MANBOT]2.0.CO;2. S2CID 86235429.
  14. Buchanan, S.W.; Timm, B.C.; Cook, R.P.; Couse, R.; Hazard, L.C. (2016). "Surface Activity and Body Temperature of Eastern Hognose Snakes (Heterodon platirhinos) at Cape Cod National Seashore, Massachusetts USA". Journal of Herpetology. 50 (1): 17–25. doi:10.1670/13-212.
  15. Goulet; Litvaitis, J.A.; Marchand, M.N. (2015). "Habitat Associations of the Eastern Hognose Snake at the Northern Edge of its Geographic Distribution: Should a Remnant Population Guide Restoration?". Northeastern Naturalist. 22 (3): 530–540. doi:10.1656/045.022.0309. S2CID 86280063.
  16. Tennant, Alan; Salmon, Gerard T.; King, Richard B. (2003). Snakes of North America (Revised ed.). Lanham, Maryland: Lone Star Books. pp. 356–359. ISBN 1-58907-003-8.
  17. Buchanan, Scott W.; Timm, Brad C.; Cook, Robert P.; Couse, Richard; Hazard, Lisa C. (2017). "Spatial Ecology and Habitat Selection of Eastern Hognose Snakes". The Journal of Wildlife Management. 81 (3): 509–520. Bibcode:2017JWMan..81..509B. doi:10.1002/jwmg.21218.
  18. "Eastern Hog-nosed Snake". Virginia Herpetological Society. Archived from the original on September 17, 2022. Retrieved April 14, 2022.
  19. Vanek, John P.; Burke, Russell L. (2020). "Insular dwarfism in female Eastern Hog-nosed Snakes (Heterodon platirhinos; Dipsadidae) on a barrier island". Canadian Journal of Zoology. 98 (3): 157–164. doi:10.1139/cjz-2019-0137. hdl:1807/99457. ISSN 0008-4301.
  20. Conant, R. (1975). A Field Guide to Reptiles and Amphibians of Eastern and Central North America, Second Edition. Boston: Houghton Mifflin. 429 pp. (Genus Heterodon and species Heterodon platyrhinos, pp. 168–170 + Plate 25 + Map 130).
  21. Smith, H.M., and E.D. Brodie, Jr. (1982). Reptiles of North America: A Guide to Field Identification. New York: Golden Press. 240 pp. ISBN 0-307-13666-3. (Genus Heterodon and species Heterodon platyrhinos, pp. 164–167).
  22. Platt, Dwight (1969). "Natural History of the Hognose Snakes Heterodon platyrhinos and Heterodon nasicus" (PDF). University of Kansas Publications. 18 (4): 253–420.
  23. Goin, C.J.; Goin, O.B.; Zug, G.R. (1978). "Heterodon". Introduction to Herpetology (Third ed.). San Francisco: W.H. Freeman. pp. 167, 328–329. ISBN 0-7167-0020-4.
  24. Schmidt, K.P.; Davis, D.D. (1941). "Heterodon contortrix". Field Book of Snakes of the United States and Canada. New York: G.P. Putnam's Sons. pp. 115–118.
  25. Edgren, Richard (1955). "The Natural History of the Hog-Nosed Snakes, Genus Heterodon: A Review". Herpetologica. 11 (2): 105–117. JSTOR 3889972.
  26. Munyer, Edward A. (1967). "Behavior of an Eastern Hognose Snake, Heterodon platyrhinos, in Water". Copeia. 1967 (3): 668–670. doi:10.2307/1442248. ISSN 0045-8511. JSTOR 1442248.
  27. Durso, Andrew M.; Mullin, Stephen J. (2013). "Intrinsic and Extrinsic Factors Influence Expression of Defensive Behavior in Plains Hog‐Nosed Snakes (Heterodon nasicus)". Ethology. 120 (2): 140–148. doi:10.1111/eth.12188. ISSN 0179-1613. Archived from the original on 2021-10-24.
  28. Boulenger, G.A. (1894). "Heterodon platyrhinus". Catalogue of the Snakes in the British Museum (Natural History). Volume II., Containing the Conclusion of the Colubridæ Aglyphæ. London: Trustees of the British Museum (Natural History). (Taylor and Francis, printers). pp. 154–156.
  29. Cooper, William E.; Secor, Stephen (2007). "Strong Response to Anuran Chemical Cues by an Extreme Dietary Specialist, the Eastern Hog-Nosed Snake (Heterodon platirhinos)". Canadian Journal of Zoology. 85 (5): 619–625. doi:10.1139/z07-041.
  30. Finn, Wendy (2005). Home Range and Spatial Ecology of Eastern Hognose Snakes (Heterodon platirhinos) (PDF). Intern report, Brookhaven National Laboratory.
  31. Peet-Paré, C.A.; Blouin-Demers, G. (2012). "Female Eastern Hog-nosed Snakes (Heterodon platirhinos) choose nest sites that produce offspring with phenotypes likely to improve fitness". Canadian Journal of Zoology. 90 (10): 1215–1220. doi:10.1139/z2012-091. ISSN 0008-4301.
  32. Young, Robert (1992). "Effects of Duvernoy's Gland Secretions From the Eastern Hognose Snake, Heterodon Platirhinos, on Smooth Muscle and Neuromuscular Junction". Toxicon. 30 (7): 775–779. doi:10.1016/0041-0101(92)90013-U. PMID 1509497.
  33. Robson, Laura E.; Blouin-Demers, Gabriel (2013). "Eastern Hognose Snakes (Heterodon platirhinos) Avoid Crossing Paved Roads, but Not Unpaved Roads". Copeia. 2013 (3): 507–511. doi:10.1643/CE-12-033. ISSN 0045-8511.
  34. Spinner, Leo (October 23, 2015). "The Natural History and Captive Care of the Eastern Hognose Snake". Reptiles. Retrieved November 16, 2023.
  35. Heterodon platirhinos at the IUCN Red List. Accessed 14 September 2007.
  36. Klemens, M.W. (1993). Amphibians and Reptiles of Connecticut and Adjacent Regions. State Geological and Natural History Survey of Connecticut.
  37. Therres, GD (1999). "Wildlife species of regional conservation concern in the northeastern United States". Northeast Wildlife.
  38. Seburn, D (2009). "Recovery strategy for the eastern hognose snake (Heterodon platirhinos) in Canada". Species at Risk Act Recovery Series.
  39. NEPARC (2010). "Northeast amphibian and reptile species of regional responsibility and conservation concern". Northeast Partners in Amphibian and Reptile Conservation (NEPARC) Publication 2010-1.
  40. Buchanan, Scott (2012). "Ecology of the Eastern Hognose Snake (Heterodon platirhinos) at Cape Cod National Seashore, Barnstable County, Massachusetts" (PDF). Montclair State University. Archived from the original (PDF) on August 11, 2016.
  41. Gibbons, J.W.; Scott, D.E.; Ryan, T.J.; Buhlmann, K.A.; Tuberville, T.D.; Metts, B.S.; Greene, J.L.; Mills, T.; Leiden, Y.; Poppy, S.; Winne, C.T. (2000). "The global decline of reptiles, déjà vu amphibians". BioScience. 50 (8): 653–666. doi:10.1641/0006-3568(2000)050[0653:TGDORD]2.0.CO;2.
  42. Akresh, M.E.; King, D.I.; Timm, B.C.; Brooks, R.T. (2017). "Fuels Management and Habitat Restoration Activities Benefit Eastern Hognose Snakes (Heterodon platirhinos) in a Disturbance-Dependent Ecosystem". Journal of Herpetology. 51 (4): 468–476. doi:10.1670/16-049.

Further reading

  • Conant, Roger, and William Bridges (1939). What Snake Is That? A Field Guide to the Snakes of the United States East of the Rocky Mountains. With 108 drawings by Edmond Malnate. New York and London: D. Appleton-Century. Frontispiece map + viii + 163 pp. + Plates A–C, 1–32. (Heterodon contortrix, pp. 39–40 + Plate 4, Figure 11; Plate 5, Figure 13).
  • Holbrook, J.E. (1842). North American Herpetology; or, A Description of the Reptiles Inhabiting the United States. Vol. IV. Philadelphia: J. Dobson. 138 pp. (Heterodon platirhinos, including synonym Heterodon niger, pp. 62–70, Plates XVI–XVII).
  • Latreille, P.A. In: Sonnini, C.S., and P.A. Latreille (1801). Histoire naturelle des reptiles, avec figures dessinées d'apres nature; Tome IV. Seconde Partie. Serpens. Paris: Crapelet. 410 pp. (Heterodon platirhinos, new species, pp. 32–37). (in French).
  • Morris, Percy A. (1948). Boy's Book of Snakes: How to Recognize and Understand Them. A volume of the Humanizing Science Series, edited by Jaques Cattell. New York: Ronald Press. viii + 185 pp. ("The Hog-Nosed Snake", "Heterodon platyrhinos ", pp. 52–57, 179).
  • Zim, H.S., and H.M. Smith (1956). Reptiles and Amphibians: A Guide to Familiar American Species: A Golden Nature Guide. New York: Simon and Schuster. 160 pp. (Heterodon contortrix, pp. 81, 156).