Species Profile

Eastern Hog-nosed Snake

Scientific Name: Heterodon platirhinos
Other/Previous Names: Eastern Hognose Snake
Taxonomy Group: Reptiles
COSEWIC Range: Ontario
COSEWIC Assessment Date and Status Change: May 2021
COSEWIC Status: Threatened
COSEWIC Status Criteria: A2cde+3cde+4cde
COSEWIC Reason for Designation: This large, mobile snake has a patchy distribution in southern and south-central Ontario, where it relies on habitats with sandy soils for oviposition and hibernation, and feeds mainly on toads. The population faces a suspected continuing decline in abundance, based on ongoing threats. These include road traffic mortality, road construction and expansion, urban expansion, agricultural intensification, introduced and abnormally abundant predators, and persecution. Based on recent extirpation of five subpopulations, there appear to be significant range contractions in landscapes highly modified by agriculture and urbanization in the south, as well as in more intact landscapes in the northeast, including protected areas. The magnitude of decline is uncertain because this species is more challenging to monitor than other, similarly sized snakes. However, declines are suspected to exceed 30% over the next 20 years.
COSEWIC History of Status Designation: Designated Special Concern in April 1997. Status re-examined and designated Threatened in November 2001, November 2007, and May 2021.
SARA Status: Schedule 1, Threatened
Date of Listing (yyyy-mm-dd): 2003-06-05

Please note that this information is provided for general information purposes only. For the most up to date and accurate list of species listed under the Species at Risk Act, please see the Justice Laws Website.

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Quick Links: | Photo | Description | Distribution and Population | Habitat | Biology | Threats | Protection | Recovery Initiatives | Recovery Team | National Recovery Program | Documents

Image of Eastern Hog-nosed Snake

Eastern Hog-nosed Snake Photo 1
Eastern Hog-nosed Snake Photo 2

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Description

The Eastern Hog-nosed Snake owes its name to the upturned scale, unique to hog-nosed snakes, at the tip of its snout. This stout-bodied snake can reach a length of 115 cm, with males generally being smaller than females. Individuals of this species are highly variable in colour and pattern. Some individuals have a distinctive pattern of irregular blotches down the back, alternating with dark spots along the side, on a background of grey, brown, tan, olive, orange, yellow, or pinkish colour, whereas others lack all patterning and are typically plain grey, brown, olive, or black. Dark neck blotches are visible in all but the darkest individuals. The belly is often mottled and can be yellowish, grey, cream, or pinkish. The chin and throat are usually lighter than the rest of the underside. Hatchlings of this species have dark blotches on the back and smaller blotches on the sides with a light grey or brown background. This pattern is present even in individuals that will be unpatterned and uniformly coloured as adults. The defensive display of the Eastern Hog-nosed Snake when it is approached by humans is usually sufficient for identification: when it feels threatened, it rears back and flattens out its head and neck like a cobra, then hisses and may strike. This behaviour often leads people to think this harmless snake is venomous.

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Distribution and Population

The Eastern Hog-nosed Snake is found in the eastern half of the United States, from southern New England, western Minnesota and South Dakota south to Texas and east to Florida. In Canada, it is restricted to two geographically distinct areas in southern and south-central Ontario: the Carolinian region of southwestern Ontario and the Great Lakes–St. Lawrence region of central Ontario south of the French River and Lake Nipissing and east of Georgian Bay. The Eastern Hog-nosed Snake has been extirpated from the regional municipalities of Halton, Peel, and York, as well as from Pelee Island and from Point Pelee National Park of Canada. In addition, the records from Bruce, Grey, and Prince Edward counties are considered historical; the species may be extirpated from these areas as well as from Hastings and Durham counties. It is difficult to estimate the abundance of the Eastern Hog-nosed Snake from the isolated populations in Ontario because few studies have been conducted on this species in Canada. It appears, however, that these snakes are almost always found in low densities in Canada. Over the past 20 years, the Eastern Hog-nosed Snake has been extirpated from 8% of known occurrences in Ontario, and 35% of known occurrences are ranked as historical or unconfirmed. There are 126 confirmed records in the province, many of which are based on single observations. This suggests that some records represent small populations or remnants of extirpated populations. The total number of adult snakes has been estimated at fewer than 7500. Over the long term, the reduction in the amount of available habitat, the expanding road network and increased vehicle traffic in south-central Ontario, together with the threat of human persecution, point to a continuing decline in Eastern Hog-nosed Snake populations in Canada.

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Habitat

The Eastern Hog-nosed Snake prefers habitats with sandy, well-drained soil and open vegetative cover, such as open woods, brushland, fields, forest edges and disturbed sites. The species is often found near water. Eastern Hog-nosed Snakes in shoreline areas often rely on driftwood and other ground cover in beach and beach dune habitats, where toads, their prey of choice, are found. South of Parry Sound, in the Georgian Bay region, the species appears to prefer fields and forest habitats that have been modified by people rather than rock, wetland or aquatic habitats. They can live in slightly cooler areas if there are exposed south-facing sandy slopes that provide soil conditions that are warm enough for incubation. The types of habitats preferred by Eastern Hog-nosed Snakes have declined or disappeared because the habitats have soils favourable for agriculture or for beach and water-related recreation.

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Biology

In Ontario, the Eastern Hog-nosed Snake appears to reach reproductive maturity at age four or five, whereas in the central United States, maturity is reached around age two. Mating occurs in spring and in August and early September. Females may mate with more than one male. The Eastern Hog-nosed Snake is oviparous; females lay between 7 and 37 eggs in burrows, or nests, which they dig with their upturned snout in sandy soil about 10 to 20 cm below the surface. They may also nest in cavities under rocks as well as under driftwood on beaches. Egg laying begins in late June and continues for two to three weeks. Hatching occurs in late August or early September, after two months of incubation. In Canada, in the northern portion of the species’ range, females may need to excavate nests in locations that provide enough sunlight to ensure warm conditions for the incubation of the eggs. In addition, the Eastern Hog-nosed Snake shows high nest site fidelity from year to year. Eastern Hog-nosed Snakes hibernate from October to April in sandy soil below the frost line. Unlike other species, the Eastern Hog-nosed Snake does not hibernate communally. If existing suitable sites, such as burrows, are not available, the snakes may excavate a hibernation site; they sometimes exhibit hibernation site fidelity. Eastern Hog-nosed Snakes appear to hunt mainly using their sense of smell. In the United States, they feed on toads, frogs and lizards, as well as certain insects, amphibians other than toads and frogs, molluscs, birds, crustaceans, turtles, earthworms, and spiders. Adult snakes in the wild in Canada are known to feed only on toads. Eastern Hog-nosed Snakes may experience higher natural mortality by predation than other snake species in Ontario because they are active predators and move about a lot. Predators include mustelids, such as skunks and weasels, and other medium-sized mammals, such as foxes and raccoons. Raptors and wild turkeys are also predators of young and adult snakes. Pet and feral cats and dogs are also likely predators. Eastern Hog-nosed Snakes in or near urban areas suffer high rates of human-caused mortality. This species, which is harmless, is often taken for a venomous snake because, when threatened, it rears back and flattens its head like a cobra, then hisses and may strike. If its aggressive behaviour fails to scare off an attacker, the Eastern Hog-nosed Snake will play dead. It may also defecate and cover itself with foul-smelling excrement, roll onto its back with its tongue extended, and possibly even exude blood from its mouth.

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Threats

In southwestern Ontario, the species has suffered extensive habitat loss from agriculture and the rapid increase in housing development. In that area, the species faces several threats, particularly increased mortality and severe habitat fragmentation caused by the expanding road network and increased traffic. In addition, the species is highly mobile and moves about a lot (for a snake); this increases the risk of mortality associated with roads. Limiting factors for this species include the availability of suitable habitat, especially sandy soils for nesting and hibernation. The lack of nesting sites is particularly noticeable in Wasaga Beach Provincial Park. Human persecution is also a major threat because of the snake's intimidating defensive display. This persecution is especially significant in urbanized areas surrounding snake habitat, such as Wasaga Beach Provincial Park. Given the increasing demand for these snakes in the pet trade, poaching for the illegal wildlife trade is a growing threat. The availability of prey is another major limiting factor for Eastern Hog-nosed Snake populations. Because these snakes specialize in feeding on toads, reductions in the toad population could cause a decline in Eastern Hog-nosed Snake populations. The Eastern Hog-nosed Snake has disappeared from Point Pelee and from Pelee Island, where Fowler’s toads have also been extirpated (although American toads remain common). Nest predation by raccoons may also be a significant threat.

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Protection

Federal Protection

The Eastern Hog-nosed Snake is protected under the federal Species at Risk Act (SARA). More information about SARA, including how it protects individual species, is available in the Species at Risk Act: A Guide.

In Ontario, the Eastern Hog-nosed Snake is protected under the Ontario Fish and Wildlife Conservation Act, 1997. Under this act it is an offence to kill, harass or capture individuals of this species. The species and its habitat are also protected under the Ontario Endangered Species Act, 2007. Some of the known populations are in protected areas such as the Pinery, Komoka, Rondeau and Wasaga Beach provincial parks.

Provincial and Territorial Protection

To know if this species is protected by provincial or territorial laws, consult the provinces' and territories' websites.

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Recovery Initiatives

Status of Recovery Planning

Recovery Strategies :

Name Recovery Strategy for the Eastern Hog-nosed Snake (Heterodon platirhinos) in Canada
Status Final posting on SAR registry

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Recovery Team

Recovery Team for Eastern Foxsnake and Eastern Hog-nosed Snake

  • Gary Allen - Chair/Contact - Government of Ontario
    Phone: 705-725-7517  Fax: 705-725-7584  Send Email
  • Angela McConnell - Chair/Contact - Environment Canada
    Phone: 416-739-5715  Fax: 416-739-4560  Send Email

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Recovery Progress and Activities

Summary of Research/Monitoring Radio telemetry data has been used to analyze population viability, demographics, and movement of the Eastern Hog-nosed Snake in Wasaga Beach, Ontario, since 2001. Also, radio telemetry studies on movement patterns of Eastern Hog-nosed Snakes were conducted as part of the environmental assessment of the effect of the Highway 69 expansion near Parry Sound on threatened snake species. Road kill data is being collected in Southern Ontario to determine road kill hot-spots to inform planning of campground roads and sites. The Natural Heritage Information Centre has compiled all known records of the Eastern Hog-nosed Snake in Ontario in a database that is updated as new information is obtained. Surveys for Eastern Hog-nosed Snakes were undertaken at Rondeau Provincial Park during 2000 and 2001, at Long Point National Wildlife Area from 1996-1999 and again from 2003-2004, at St. Williams Crown Forest from 1997-2004, and along the Trent-Severn waterway during 2005. Observations of Eastern Hog-nosed Snakes have been recorded for decades at Georgian Bay Islands National Park. Since 1993, all Hog-nosed Snakes captured in the high use areas of the park have been implanted with a Passive Integrated Transponder tag (for identification), measured, weighed, and released. Since that time, park staff have implanted tags on 15 snakes, 13 of which were later recaptured. Between 2003 and 2005, road mortalities on neighbouring Muskoka Road 5 also have been recorded. Summary of Recovery Activities An evaluation is underway of the effectiveness of public signage and education programs in raising awareness for the Eastern Hog-nosed Snake. The Haliburton Highlands Stewardship Council is educating the public on natural heritage history, biology, habitat, and threats to vulnerable species like the Eastern Hog-nosed Snake. Their Reptile Education Workshops provide training for identifying species at risk, understanding their habitat requirements, and learning how threats can be mitigated. Natural history interpretation programs, oriented to generate awareness and reduce human persecution of snakes, are in effect in Georgian Bay Islands National Park and some other Ontario parks within the range of this species. The Toronto Zoo produces education materials used in school curriculum and park displays. Zoo staff hold meetings with private land owners and municipalities to discuss habitat protection and conservation measures. The Wasaga Beach Eastern Hog-nosed Snake Research Program prepared a 5-minute educational video in 2002 on the Eastern Hog-nosed Snake and the research being conducted at Wasaga Beach Provincial Park. The video is used during programs at the park and is also available on the Internet (www.wasagabeachpark.com). Friends of Nancy Island Historic Site and Wasaga Beach Park in conjunction with the Georgian Bay Reptile Awareness Program delivered a snake awareness program to students at the four elementary schools in Wasaga Beach from 2001-2003. Approximately 1700 students attended these presentations in a given year. The Georgian Bay Reptile Awareness Program, based in Parry Sound, provided extensive outreach on all reptile species at risk to the entire Georgian Bay area. They reached an additional 2000 students and 2300 members of the general public with programs in 2003. Programs were taken to schools (targeting grades 4 and 10) and cottage associations, and snake sensitivity training was provided to construction workers. A number of posters and brochures about the snake have been produced by a range of partners including the Georgian Bay Reptile Awareness Program, the Upper Thames River Conservation Authority, the Friends of Nancy Island Historic Site and Wasaga Beach Park, the Toronto Zoo, and the Norfolk Field Naturalists. URLs Toronto Zoohttp://www.torontozoo.com/adoptapond/Snakes.asp?sn=6 Wasaga Beach Parkhttp://www.wasagabeachpark.com/

Documents

PLEASE NOTE: Not all COSEWIC reports are currently available on the SARA Public Registry. Most of the reports not yet available are status reports for species assessed by COSEWIC prior to May 2002. Other COSEWIC reports not yet available may include those species assessed as Extinct, Data Deficient or Not at Risk. In the meantime, they are available on request from the COSEWIC Secretariat.

15 record(s) found.

COSEWIC Status Reports

  • COSEWIC assessment and update status report on the Eastern Hog-nosed Snake (Heterodon platirhinos) in Canada (2008-08-28)

    The Eastern Hog-nosed Snake, Heterodon platirhinos Latreille 1801, is a medium-sized, stout-bodied, oviparous colubrid. Its apt common name is derived from the upturned scale, unique to hog-nosed snakes, at the tip of its snout. Individuals of this species are highly variable in colour and pattern, with phenotypes ranging from colourful and blotched to melanistic. However, its tendency, when approached by humans, to inflate its neck to a cobra-like hood, hiss, and strike, eventually defecate, roll onto its back with mouth open and tongue extended, and sometimes even exude blood from its mouth and/or cloaca is usually sufficient for its identification. Although this species is harmless, it is often killed by humans perhaps alarmed by its complex defensive behaviour. Slight sexual dimorphism occurs in this species, with males generally smaller than females.

Response Statements

  • Response Statement - Eastern Hog-nosed Snake (2008-11-26)

    This species faces several threats, particularly increased mortality and severe habitat fragmentation caused by an expanding road network and increased traffic. The species is mobile for a snake, but this mobility places it at high risk when it encounters roads. The species also suffers from persecution by humans not only because it is a relatively large snake but also because of its complex defensive threats when confronted. In southwest Ontario and south of the Canadian shield, the species has suffered extensive habitat loss from agriculture and rapid increase in housing development. Poaching for the illegal wildlife trade is a growing threat.

Recovery Strategies

  • Recovery Strategy for the Eastern Hog-nosed Snake (Heterodon platirhinos) in Canada (2009-03-31)

    The Eastern Hog-nosed Snake (Heterodon platirhinos) was designated Threatened in Canada in 2001 by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC). It is widespread across much of eastern North America, but in Canada, it is limited to two areas of Ontario: the Carolinian Life Zone of southwestern Ontario, and central Ontario south of the French River and Lake Nipissing. Although the current distribution of the Eastern Hog-nosed Snake in Ontario is not completely known, it is clear that this species has declined in range. The Eastern Hog-nosed Snake has been extirpated from the Regional Municipalities of Halton, Peel, and York and possibly from Bruce, and Prince Edward counties. It has also been extirpated from Point Pelee National Park and Pelee Island. Threats faced by the Eastern Hog-nosed Snake include: habitat loss, degradation and fragmentation, roads, persecution, collecting and contaminants.

Action Plans

  • Multi-species Action Plan for Georgian Bay Islands National Park of Canada (2016-11-22)

    Georgian Bay Islands National Park (GBINP) is located in southeastern Georgian Bay in the heart of Ontario’s cottage country. Georgian Bay is home to the world’s largest freshwater archipelago, the 30,000 Islands, and the park acts as a southern gateway into this area. Comprising 63 dispersed islands and shoals the total area of the park is 14 km2 from the Centennial Group in the south to McQuade Island 50 kilometres northward. Situated just 150 km from the Greater Toronto Area (GTA), GBINP is within a half-day’s drive for millions of Canadians. Created in 1929 it is Canada’s smallest national park straddling two natural regions and forms a core protected area of the Georgian Bay Biosphere Reserve. The park lies on the edge of the Canadian Shield and is home to both northern and southern plants and animals. The islands are renowned for the variety of reptiles and amphibians they support. The park also has significant cultural value, having been occupied continuously for over 5,500 years. Maintenance and restoration of ecological integrity is the first priority of national parks (Canada National Parks Act s.8(2)). Species at risk, their residences, and their habitat are therefore protected by existing national park regulations and management regimes. In addition, the Species at Risk Act (SARA) prohibitions protecting individuals and residences apply automatically when a species is listed, and all critical habitat in national parks and national historic sites must be legally protected within 180 days of being identified.

COSEWIC Annual Reports

  • COSEWIC Annual Report - 2007 - 2008 (2008-08-28)

    2008 Annual Report to the The Minister of the Environment and the Canadian Endangered Species Conservation Council (CESCC) from the Committee on the Status of Endangered Wildlife in Canada.
  • COSEWIC Annual Report 2020 to 2021 (2021-10-12)

    Over the past year COSEWIC assessed a total of 66 wildlife species, of which 4 were assigned a status of Not at Risk. Of these 66, COSEWIC re-examined the status of 41 wildlife species; of these, 80% were reassessed at the same or lower level of risk. To date and with the submission of this report, COSEWIC’s assessments now include 826 wildlife species in various risk categories including 369 Endangered, 196 Threatened, 239 Special Concern, and 22 Extirpated (i.e. no longer found in the wild in Canada). In addition, 19 wildlife species have been assessed as Extinct, 62 wildlife species have been designated as Data Deficient, and 202 have been assessed as Not at Risk.

Permits and Related Agreements

  • Explanation for issuing permit(#29), persuant to the provisions of section 73 of SARA (2006-06-30)

    To conduct a Species at Risk snake survey within this area to assist the federal government client in determining the presence/absence of SAR species within the study area. The survey methodology will involve: 1. Education of personnel to identify and report specimens as observed; 2. To conduct an ongoing incidental specimen observation survey; 3. To conduct a detailled site search within likely habitat areas; 4. Specimens to be live captured, examined, and released in situ. Specimens not to be injured, killed or removed; and 5. PIT tagging of captured Eastern Hog-nosed snakes.
  • Explanation for issuing permit(#46582), persuant to the provisions of section 74 of SARA (2021-02-01)

    Environmental DNA (eDNA) methods are being developed to aid in the assessment and monitoring of species that are rare or difficult to observe directly. Effective eDNA programs require the development of reference primers (based on sample tissues/DNA obtained directly from target species) to accurately detect when target species are present in the environment. This project will collect DNA from water and genetic material from dead specimens of species at risk for development of an environmental DNA (eDNA) primer or to test the efficacy of an existing primer. The collection of the eDNA samples will take place in the Trent-Severn Waterway National Historic Site, the Rideau Canal National Historic Site, Point Pelee National Park, Georgian Bay Islands National Park, Elk Island National Park and the Rouge National Urban Park.
  • Explanation for issuing permit(#SARA-OR-2007-0055), persuant to the provisions of section 73 of SARA (2007-05-18)

    To conduct a Species at Risk snake survey within this area to assist the federal government client in determining the presence/absence of SAR species within the study area. The survey methodology will involve: 1. Education of personnel to identify and report specimens as observed; 2. To conduct an ongoing incidental specimen observation survey; 3. To conduct a detailled site search within likely habitat areas; 4. Specimens to be live captured, examined, and released in situ. Specimens not to be injured, killed or removed; and 5. PIT tagging of captured Eastern Hog-nosed snakes.
  • Explanation for issuing permit(#SARA-OR-2007-0056), persuant to the provisions of section 73 of SARA (2007-05-24)

    An inventory of species and their abundance will be recorded using walking transects. No animals or plants will be collected although some may be handled to verify identification. Any animals handled will be done so according to the animal care committee protocol of CWS.
  • Explanation for issuing permit(#SARA-OR-2007-0061), persuant to the provisions of section 73 of SARA (2007-07-24)

    The purpose of this investigation is to survey the property for hazardous materials which are detrimental to public safety. This survey will require the clearing of vegetation along survey lines throughout much of the property. Vegetation clearing activities will be undertaken strategically to ensure public safety is maintained on the site and that any potential impacts to any schedule 1 species at risk are avoided or minimized.
  • Explanation for issuing permit(#SARA-OR-2008-0076), persuant to the provisions of section 73 of SARA (2008-03-25)

    To conduct a Species at Risk snake survey within this area to assist the federal government client in determining the presence/absence of SAR species within the study area. The survey methodology will involve: 1. Education of personnel to identify and report specimens as observed; 2. To conduct an ongoing incidental specimen observation survey; 3. To conduct a detailled site search within likely habitat areas; 4. Specimens to be live captured, examined, and released in situ. Specimens not to be injured, killed or removed, and: 6. PIT tagging of captured Eastern Hog-nosed Snakes.
  • Explanation for issuing permit(#SARA-OR-2008-0103), persuant to the provisions of section 73 of SARA (2008-12-01)

    The purpose of this investigation is to survey the property for hazardous materials which are detrimental to public safety. This survey will require the clearing of vegetation along survey lines throughout much of the property. Vegetation clearing activities will be undertaken strategically to ensure public safety is maintained on the site and that any potential impact to any schedule 1 species at risk are avoided or minimized. This is an amendment to the original permit issued December 1, 2008.
  • Explanation for issuing permit(#SARA-OR-2009-0118), persuant to the provisions of section 73 of SARA (2009-09-16)

    The construction project on these parcels of land is for the purpose of installing a water treatment plant (with a water intake located in Twelve Mile Bay) and associated distribution infrastructure. Treated water will be distributed through a system of watermains to three land parcels that comprise the reserve lands. Through previous field survey it has been established that there are SARA listed species of fauna present (or suspected to be present) in the area. It is proposed that all SARA species be monitored during the construction season and any that are deemed to be threatened by machinery or work activities be live captured, transported and released on adjacent property by qualified biologists.
  • Explanation for issuing permit(#SARA-OR-2011-0165), persuant to the provisions of section 73 of SARA (2011-05-01)

    The Department of National Defence is conducting unexploded ordnance (UXO), environmental and cultural resource investigation within the former Camp Ipperwash. The UXO investigation follows previous work conducted under Permit SARA-OR-2008-0103. The current activity involves siting 34 UXO calibration plots on the property, each covering 900 square metres. Within each plot the source of the geophysical anomaly will be excavated and physically characterized. The calibration plots will first be placed electronically on maps to select the best locations with ideal site coverage and to ensure that known occurrence of species at risk listed under SARA will not be affected. The plots will also be sited in areas to minimize vegetation clearance. Should vegetation clearance be required it will be completed in accordance with direction given by the senior/experienced terrestrial SAR biologists on site. Cultural Resource (archaeological) resources will be investigated in each of the 34 calibration plots, and an additional 10 plots of the same dimensions. The cultural resource plots will be based on a 5 x 5 m grid pattern with hand excavated test pits at the intersecting node points of the grids. The test pits will have a 30cm diameter and be excavated by hand,. The environmental investigation will consist of surface soil and water and subsurface soil and groundwater sample collection for analysis. Approximately 100 potential areas of environmental concern have been identified on the property, and each will require three boreholes 2 to 6 inches in diameter.
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