Southern hognose snake

Holotype: not located, perhaps lost according to Edgren, 1952, Bull. Zool. Nomencl. 6:354-355.

These snakes reach a maximum size of about 61 cm, the average size is between 50 to 53 cm. All species of this genus can be recognized by the characteristic upturned and pointed snout. The dorsal pattern in H. simus is less variable than H. platirhinos. It consists of yellowish-brown scales contrasted by dark vertebral blotches, separated by smaller orange blotches. The ventral scales are sandy-gray (Tennant, 2003).

The genus Heterodon is endemic to North America. Heterodon simus, the Southern Hognose Snake, is found in the southeastern United States, primarily from North and South Carolina, south to the coastal tip of Florida, and west as far as Mississippi.

Biogeographic Regions: nearctic (Native )

Southeastern USA: from eastern North Carolina southward to the coastal plain of South Carolina and Georgia to Lake Okeechobee and Tampa in Florida, and westward through the florida panhandle, Alabama (north to Calhoun County), and southeastern Mississippi (to the Pearl River separating Louisiana and Mississippi).

endemic to a single nation

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

Global Range: (200,000-2,500,000 square km (about 80,000-1,000,000 square miles)) This snake occurs on the Coastal Plain from eastern North Carolina to southern Florida (Lake Okeechobee), west to southeastern Mississippi (Conant and Collins 1991, Palmer and Braswell 1995, Tennant 1997, Ernst and Ernst 2003). It is now very rare (or possibly extirpated) in the western part of the range in Mississippi and Alabama.

Heterodon simus, is a short, stoutly built snake with a pointed upturned snout and wide neck. The colors range from yellow, to light brown, or grayish, and are often tinted with colors of red. Coloration is fairly constant, not highly variable as in Eastern Hognose Snakes. The scales are keeled, and usually in rows of 25. The underside of tail is not distinctively lighter in color. The anal plate is divided in halves. This is the smallest of Heterodon species, they range in total length from 330 to 559 mm, females are usually larger than males. Heterodon means 'different tooth', which refers to the enlarged teeth on the rear of the upper jaw. These teeth inject a mild venom into their prey, and serve to puncture inflated toads like a balloon to enable ingestion. They use their blunt nose to search through leaf litter and soil for prey.

Length: 61 cm

Differs from the eastern hognose snake (H. platirhinos) in that the underside of the tail is not conspicuously paler than the belly (Conant and Collins 1991).

• Terrestrial

Habitats often include areas of sandy woods, fields, dry river floodplains, and hardwood hammocks. They prefer loose, sandy soils and pine forests. Southern Hognose Snakes are found in temperate zones that range from a low of 20 degrees in winter to highs over 100 degrees Fahrenheit in summer months.

Terrestrial Biomes: forest

Abundant in sandhill terrain, stabilized coastal sand dunes, and disturbed terrain where sandy subterranean soil has been exposed. H. simus tend to be more fossorial than other Heterodon species (Tennant, 2003).

Comments: This snake inhabits open, xeric habitats with well-drained, sandy or sandy-loam soils such as sand ridges, stabilized coastal sand dunes, pine flatwoods, mixed oak-pine woodlands and forests, scrub oak woods, and oak hammocks; also old fields and river floodplains (Ashton and Ashton 1981, Palmer and Braswell 1995, Tennant 1997, Ernst and Ernst 2003). This snake spends considerable time burrowed in the soil.

Non-Migrant: Yes. At least some populations of this species do not make significant seasonal migrations. Juvenile dispersal is not considered a migration.

Locally Migrant: No. No populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).

Locally Migrant: No. No populations of this species make annual migrations of over 200 km.

Southern Hognose Snakes eat mostly toads, primarily Scaphiopus species, and occasionally frogs and lizards.

Comments: Eats mainly frogs and toads, sometimes lizards and small mammals (Ernst and Barbour 1989). May use snout to excavate buried toads.

Like H. platirhinos, H. simus is a toad specialist (Carr, 1940; Tennant, 2003), and has developed a resistance to the toxic bufadienolides produced in the paratoid and skin glands of toads.

Note: For many non-migratory species, occurrences are roughly equivalent to populations.

Estimated Number of Occurrences: 21 - 80

Comments: This species is represented by a large number of collection sites, but the species appears to be no longer extant at many of these (Tuberville et al. 2000). Palmer and Braswell (1995) mapped several dozen collection sites in North Carolina.

2500 - 100,000 individuals

Comments: Adult population size is unknown but presumably is at least several thousand. This is a secretive, fossorial snake that is difficult to detect, so it may be more numerous than available observations indicate. Nevertheless, it appears to uncommon to rare throughout much of the historical range. In Florida, Tennant (1997) rated it as uncommon to rare but occasionally locally common. Different survey methods may yield different impressions of abundance. For example, in west-central Florida, H. simus was locally common and one of the most frequently observed snake species during pedestrian surveys on roads, but it was seldom trapped by drift fences (Enge and Wood 2002, 2003).

Mostly active during the early summer in the morning and and evening when toads are out (Tennant, 2003).

When disturbed, H. simus will hiss and flatten it's head and neck. It may also feign death, like other members of its genus (Tennant, 2003).

Very little is known of their reproduction. Eggs are usually recorded in clutches of 6-14 eggs and are laid in late spring or early summer.

Clutches of 6-10 eggs have been reported. Based on Heterodon nasicus, females probably mature at 2-3 years, and some individuals likely live well into their second decade. Hence generation length may be 5-10 years.

Oviparous

Southern Hognose Snake populations are rapidly declining throughout their range, they are believed to have been extirpated from at least two states already. Primary factors contributing to their decline include urbanization, habitat destruction, the introduction of red fire ants, increases in predation by feral cats and dogs, and pollution. Southern Hognose Snakes occupy similar habitats to Red-cockaded Woodpeckers, a federally listed endangered species. H. simus is being considered for federal listing as an endangered species.

US Federal List: threatened

CITES: no special status

IUCN Red List of Threatened Species: vulnerable

United States

Rounded National Status Rank: N2 - Imperiled

Rounded Global Status Rank: G2 - Imperiled

Reasons: Relatively small range on the Coastal Plain of the southeastern United States; possibly extirpated from Mississippi and Alabama, apparently now rare and declining throughout most of the range, but still locally common in some areas; research on the threat posed by imported fire ants is needed.

Intrinsic Vulnerability: Moderately vulnerable

Global Short Term Trend: Decline of 10-30%

Comments: Current trend data are unavailable, but this snake appears to be declining in area of occupancy, number of subpopulations, and abundance (Tuberville et al. 2000). However, data on commercial collection for the pet trade indicate that this snake is still locally common in at least three areas of Florida (Enge and Wood 2003).

Assuming a generation time of around 5 years, the rate of decline over the past three generations (15 years) is unknown but may exceed 10 percent.

Global Long Term Trend: Decline of 30-70%

Comments: Trend cannot be quantified with any confidence, but clearly there has been a substantial decline (Tuberville et al. 2000). Most records are based on specimens that were collected/observed a long time ago and probably reflect only historical presence, as recent records for many of these sites are lacking (Tuberville et al. 2000). No recent (1983-1998) records are available for Mississippi, Alabama, and much of the historical range within Georgia. The species was considered quite common in southwestern Georgia in the 1940s and 1950s, but only a few occurrences have been noted in this area since 1970 (Tuberville et al. 2000). In South Carolina, the species has been seen recently (since 1980) in only 10 of the 20 counties from which it was once known. The population is apparently stable at the Savannah River Plant site in South Carolina. This snake apparently has declined in abundance throughout the range.

Degree of Threat: A : Very threatened throughout its range communities directly exploited or their composition and structure irreversibly threatened by man-made forces, including exotic species

Comments: Significant threats remain poorly understood but are here estimated to be of at least moderate scope and severity. Predation of eggs and hatchlings by red imported fire ants (IFA) may be a factor in the decline (Tuberville et al. 2000). The snake's disappearance from certain areas is associated with heavy red IFA infestations.

Other factors suggested to be of potential importance include loss of habitat to intensive agricultural/silvicultural activities, widespread pesticide application, road mortality, and the general persecution of snakes by humans.

This species apparently can persist in areas of fragmented and altered upland habitats, although cumulative road mortality may be a significant factor, especially for hatchlings (Enge and Wood 2003).

Management Requirements: Implement/continue seasonally appropriate burning programs in pyric communities. Environmentally benign fire ant control may be beneficial (necessary?) on sites that still support H. simus but that are at edge of or within the belt of fire ant expansion.

Management Research Needs: Better information on ecology and behavior is needed (Ernst and Barbour 1989). See Management Summary.

Global Protection: Unknown whether any occurrences are appropriately protected and managed

Comments: Probably some occurrences are in protected areas. However, this snake appears to have disappeared in some large protected areas with relatively pristine habitats (Gibbons et al. 2000).

Needs: Conservation needs include the following: Protect large tracts of suitable habitat. Limit pesticide use in preferred habitat types. Educate public regarding snake's harmlessness. Control fire ants on certain parcels of important habitat.

This species has an important predatory niche in the environment. Aside from this, it rarely affects humans.

Stewardship Overview: Research is urgently needed to determine the factor or combination of factors responsible for the precipitous decline. Once the cause(s) is known, appropriate pro-active management measures may be implemented, and activities shown to be deleterious may be avoided. Specific research on the relationship, if any, between the disappearance of this species and the appearance of imported fire ants is needed.