Southern hognose snake  (Heterodon simus)

The southern hognose snake is classified as Vulnerable (VU) on the IUCN Red List (1).

The southern southern hognose snake (Heterodon simus) is the smallest member of the genus heterodon (4). All members of the genus have a characteristic upturned snout (5). This species has a tan coloured body with square blocks of brown running down its back, and orange scales between the brown patches. Small, round, dark brown blotches run along its sides and it has a cream or light grey belly with no markings (4) (6).The southern hognose snake is rough to the touch, as it has keeled, or ridged scales (7). The female southern hognose snake is larger than the male (4).

Endemic to North America, the southern hognose snake is only found in the southeast of the United States. It is distributed from eastern North Carolina to southern Florida, and as far west as south-eastern Mississippi. However, a recent population survey failed to locate the southern hognose snake in Mississippi or Alabama, and it is possible that it has been eliminated from these states (1) (4).

The southern hognose snake can be found in dry, open areas, such as coastal sand dunes, river floodplains, and mixed oak-pine woodlands. It prefers sandy or loamy, well-drained soil, which it can easily burrow in (1) (7) (8) (9) (10).

The southern hognose snake is a secretive species and is rarely spotted in the wild, spending much of its time in underground in burrows, 20 to 30 centimetres below the surface. It is thought to be diurnal, emerging from its burrow in early morning or late afternoon (4) (11).

Little is known about the southern hognose snake’s breeding biology, and most of the available information has been obtained through studying captive animals. The breeding season is thought to be from May to June, and the female southern hognose snake will lay a clutch of 6 to 14 eggs from late spring to early summer. The eggs take 65 to 70 days to hatch and the hatchlings emerge between mid-September and early October (4) (7).

Contrary to popular belief, the southern hognose snake does not produce toxic venom and it is not considered to be a dangerous species, although it does have a painful bite (12). It feeds mainly on toads, which it digs out of loose soil using its upturned snout. It then grasps the prey using its enlarged rear fangs (4) (6) (11). Although toads form the majority of the southern hognose snake’s diet, it also feeds on other small vertebrates such as lizards, mice and frogs (7).

To deter predators, the southern hognose snake uses a variety of defensive behaviours including puffing up its head, flattening its neck, hissing continuously and pretending to strike. The snake also employs an alternative strategy, rolling onto its back and playing dead. The southern hognose snake’s defensive display is less elaborate than that of other hognose snakes (4) (6) (11).

A lack of information on the abundance and distribution of the southern hognose snake makes it difficult to determine the threats to this species. However, the most important factors are thought to be habitat loss and invasive species (4).

The fire ant (Solenopsis invicta), an invasive species introduced to the USA, predates on reptile eggs and hatchlings (13). The specific impact these ants have on the southern hognose snake is unknown, but areas with heavy fire ant infestations have recorded a disappearance of the southern hognose snake (1) (4) (6).

Lack of proper fire management has resulted in the loss of dry sand hills, which are an important habitat for the southern hognose snake. Road networks have also fragmented habitats, and although the southern hognose snake can withstand this disturbance, road mortality is a significant threat, especially for hatchlings (1) (4) (7). Further concerns include pesticide application and the habitual persecution of snakes by humans (1).

There is no formal federal protection for the southern hognose snake, although it occurs in some protected areas (1) (7). Worryingly, this species seems to have disappeared from relatively undisturbed protected sites. It is important to investigate the causes of the southern hognose snake’s decline, and create and implement appropriate management measures. Recommendations include protecting large areas of suitable habitat, controlling imported fire ants, limiting pesticide application, and promoting the harmless nature of the southern hognose snake to the general public (1).

More information on reptile conservation:

• The International Reptile Conservation Foundation:
  http://www.ircf.org/