Species Description
Southern Hog-nosed Snakes (Heterodon simus) are small, stout-bodied colubrid snakes associated with the Longleaf Pine ecosystem and similar xeric habitats of the southeastern U.S. They are a harmless species, although they are sometimes mistaken for pygmy rattlesnakes, copperheads, or other small pit vipers. Southern Hog-nosed Snakes attain a maximum length of 61 cm (24 in.), but most adults range from 45–55 cm (18–22 in.) in total length, while hatchlings generally range from 13–18 cm (5–7 in.). Female snakes (typically > 50 cm in total length) are generally larger than males (usually < 50 cm in total length). Despite their short total lengths, Southern Hog-nosed Snakes are often quite chunky, especially when compared to snakes of similar lengths.
Southern Hog-nosed Snakes are generally light brown to grayish, with dark black, brown, or reddish blotches running down the dorsum, which turn into bands near the tail. There are rows of smaller dark spots along the snake’s sides, and many individuals have slight rust-colored pigmentation between the dark blotches on the dorsum. The venter is light brown to cream-colored, which continues all the way onto the underside of the tail. Southern Hog-nosed Snakes have a distinct, sharply upturned, and pointed snout, which gives them quite an endearing appearance. In general, Southern Hog-nosed Snakes are smaller and less variable in pattern than the closely related and far more common Eastern Hog-nosed Snake (Heterodon platirhinos). Southern Hog-nosed Snakes can be confidently distinguished from their eastern relatives by their uniform light pigmentation on the belly and underside of the tail, as well as a more sharply upturned snout.
Like other North American Heterodon, Southern Hog-nosed Snakes sometimes perform convincing defensive displays when they feel threatened. These displays involve flattening their necks to form a “hood,” loud hissing, gaping, and even mock strikes. If this display does not deter a potential predator, some individuals will feign death, although they usually aren’t as eager or dramatic in their death displays as Eastern Hog-nosed Snakes.
Taxonomy
The Southern Hog-nosed Snake is a small snake species in the family Colubridae. It was originally classified under the genus Coluber in 1766 by Carl Linnaeus but was reclassified under the genus Heterodon in 1801 by Pierre André Latreille. There are currently no recognized subspecies.
The scientific name for the Southern Hog-nosed Snake is Heterodon simus. The genus Heterodon comes from the Greek words heteros, meaning “different,” and odon, meaning “tooth.” The species name simus comes from the Greek word simós, meaning “snub-nosed.”
Distribution
The Southern Hog-nosed Snake historically ranged across the Coastal Plain of the southeastern United States, from southern Mississippi to southeastern North Carolina. Its distribution also included the northern half of Florida. Populations are declining across much of this range, although the secretive nature of this snake makes it difficult to study.
Today, Southern Hog-nosed Snake populations exist in isolated patches of remaining habitat scattered across their former range. Many of these populations are likely completely isolated from one another due to the distances between suitable habitat patches. There have been no observations in Mississippi or Alabama in recent decades, and the species is thought to be completely extirpated from both states.
Habitat
Southern Hog-nosed Snakes prefer habitats with xeric, sandy soils that are well-drained. These include mixed oak-pine forests, scrub, longleaf pine sandhills, and oak hammocks. Because of their fossorial nature (i.e., they spend most of their time underground), Southern Hog-nosed Snakes can sometimes persist in habitats that have been degraded or disturbed by anthropogenic activities. Much of the remaining habitat for Southern Hog-nosed Snakes now exists on highly fragmented public and private lands.
Movement and Home Range
Overall, little is known about the home range sizes or surface movements of Southern Hog-nosed Snakes. They are strictly diurnal, and most of their surface activity occurs during late spring and early fall. They are most commonly encountered in the fall, particularly on roadways, as newly hatched snakes disperse.
It is assumed that male Southern Hog-nosed Snakes have larger home ranges than females and likely move farther and more frequently as well. However, there is a severe lack of data regarding their spatial ecology, not only due to their rarity and secretive nature but also because their small body size severely limits standard radio telemetry studies.
Diet
The diet of this species primarily consists of toads and spadefoot toads (Anaxyrus and Scaphiopus), but they will also feed on frogs, salamanders, lizards, and small mammals. Their sharply upturned snout is used to dig up buried toads or other prey before consuming them.
Southern Hog-nosed Snakes also produce toxic saliva in their Duvernoy’s glands, but the toxicity of this saliva has not been tested on a variety of prey species. Like other hog-nosed snake species, Southern Hog-nosed Snakes use their enlarged posterior maxillary teeth to puncture inflated anurans, making them easier to consume.
Reproduction
Reproduction occurs from mid-April to August. Male snakes courting a female will pursue her across the surface, and if she is receptive, she will allow the male to mate with her. Mating may last from three to five hours before the pair separates and goes their separate ways.
Eggs are laid in mid to late summer, with clutch sizes averaging approximately 10 eggs. Each egg measures approximately 30 x 17 mm (length by width) and weighs around 2.5 g. Eggs take 56 to 60 days to hatch, typically in September and October. Neonates are similarly colored and patterned to adults but may have more orange along the dorsum.
Conservation Concerns
Southern Hog-nosed Snakes have experienced severe declines in recent decades and are listed as Vulnerable on the IUCN Red List of Threatened Species. In 2019, the U.S. Fish and Wildlife Service (USFWS) completed a species status assessment on the Southern Hog-nosed Snake and determined it did not meet the criteria for listing under the Endangered Species Act. However, the USFWS has agreed to re-evaluate its decision by August 2025. While not federally listed, the species is considered Threatened at the state level in North Carolina, South Carolina, and Georgia. A lack of published research and the difficulty of finding this species make understanding its ecology and population trends challenging.
Habitat loss and degradation are thought to be the primary reasons for population declines in Southern Hog-nosed Snakes. Much of their primary habitat has been disturbed by modern forestry and agricultural practices or converted to other anthropogenic uses (e.g., urban areas). Because Southern Hog-nosed Snakes spend a significant amount of time underground, they are particularly susceptible to soil disturbance. The invasive Red Fire Ant (Solenopsis invicta) has also spread across the southeastern United States and has been implicated in the recent declines of Southern Hog-nosed Snake populations. Vehicle strikes and persecution by humans serve as additional sources of non-natural mortality.