Southern Hognose (Heterodon simus)

SPECIES:

Heterodon simus

SYNONYMS:

Heterodon simus (LINNAEUS, 1766)

Common name: Southern Hognose Snake

SUBSPECIES:

None

FAMILY:

Serpentes: Colubridae

DISTRIBUTION:

USA (S-Mississippi, S-Alabama, Georgia, Florida, South Carolina, SE-North Carolina)

DEFINITION

Smallest of the hognoses, this is a small stout species between 330 and 559 mm tail length, with females generally larger than males. The ground color is brown, brownish grey or tan. A series of 20-28 grayish brown, black, or dark grey dorsal blotches occur on the dorsum and alternate with rows smaller, similarly colored spots on the sides and pale interspaces. Melanism is unknown in this species. The tail has between six (6) to eleven (11) brown bands separated by pale interspaces. The venter is usually whitish, frequently stippled or mottled with gray or brown. The underside of the tail is similar in color to that of the posterior portion of the ventral surface.

The head pattern consists of two dark bands across the posterior azygous scales, the anterior edge of the frontals, and the supraoculars, as well as a broad dark band from the eye to the angle of the mouth. A middorsal and two lateral elongated nuchal blotches extend forward to the parietal scales. The rostral is sharply upturned and concave dorsally. There is a cluster of three (3) to thirteen (13) small scales (azygous) between the internasals and prefrontals. The supralabials are usually 8 in number, infralabials usually 10 or 11; nasals 2, large nostril; usually 1 loreal, often bordered by one or more small scales. The oculars are arranged in a subocular ring of 9 to 12 scales below supraocular; the dorsal scales are keeled, usually in 25 rows at midbody. Ventral scales number 112 to 132; subcaudals 28 to 49; tail length about 12 to 23% of the total length, anal plate is divided.

Sexual dimorphism in southern hognoses is pronounced, as it is with western hognoses. Male southern hognoses have fewer ventrals, more subcaudals, and dark tail bands with tails that are relatively longer than those of females. Females have more azygous scales than males and may vary in number from 3 to 13 (as opposed to 1 to 9 in males).

HABITAT

The approximate range of Heterodon simus is one hectare. Southern Hognosed snakes frequent pine forests with loose sandy soil, wire grass flatwoods, and xeric communities. Turkey Oak, Longleaf and Loblolly Pine are characteristic of the areas in which H. simus is found. Eastern facing slopes are favored as are sand ridges that form within the mature forests.

BEHAVIOR

When disturbed, Southern hognosed snakes may flatten their head and neck, spreading their vertebrae much like a cobra, owing to their nickname, "puff adder." This act gives the snake an almost impish grin when viewed from head-on. While spreading its "hood," the hognose emits a loud hissing noise like steam escaping from kettle. Occasionally the bluffing snake will repeatedly strike at the would-be attacker but with its mouth closed. If the hissing, hooding and striking fail to dissuade the attacker, the hognose will writhe with its mouth wide open, tongue lolling. Some snakes will eject blood from their lacrymal glands and emit musk from their cloaca. The belief is that a predator will instinctively ignore a dead animal that smells offensive. Southern Hognosed Snakes are less likely to feign death than their Eastern counterparts.

According to Tom Thorpe of Project Simus, out of 45 Heterodon simus identified within the study area, 44 were roadkills. The reason for this is multifold. Whereas Eastern Hognosed snakes will attempt to escape at the first sign of danger (flight response) the Southern Hognosed Snake freezes in position. Hence, they are more likely to become victims of cars and trucks on sandy roads. Primary predators include hawks, raccoons, skunks, and kingsnakes.

Southern Hognosed snakes are much more tolerant of colder weather than Eastern hognosed snakes. Thorpe reports seeing H. simus active on days when air temperatures were 35 degrees farenheit. The snakes were sunning themselves in areas where sunlight broke through the thin canopy of the pine forests. Unlike some other colubrids, H. simus hibernates singly not in hibernaculums.

CHARACTERISTICS

The Southern Hognose is thought to be most closely related to the Western Hognose; the two species being allopatric in their range distribution. Eckerman believes the development of the two species was influenced through geologic shifts and the subsequent isolation of the two species. Typically they can be seen rooting through loose sand after toads during the early morning or late afternoon hours. Southern Hognoses appear to be able to track toad scents long after they have burrowed into their holes. Although Southern Hognoses feed primarily on amphibians (Scaphiopus, Hyla and Bufo), they are also known to feed on lizards (Cnemidophorous and Scincella) and small mammals.

BREEDING BEHAVIOR

Southern hognosed snakes are most active in May when they begin breeding. Females lay between six (6) and fourteen (14) eggs in late spring or early summer. In captivity, Southern Hognosed Snakes are difficult to breed and there have been few reports of successful breeding in captivity. Most of the successful breedings that have occurred are the result of wild caught specimens reproducing in their first year and then failing to reproduce again in subsequent years.

CONSERVATION

The Southern hognosed snake is rapidly being extirpated from much of its former range; this is due to a combination of factors including urbanization; habitat destruction and pollution; an increase in predation by feral dogs and cats, racoons and the introduction of Red Fire Ants (RIFA). Due to their poor reproduction rate, difficulty of maintenance, and little known habits, collection for export and domestic sale do not appear to be major factors in their decline. The Red Cockaded Woodpecker, which shares the same type of habitat as the Southern Hognose throughout much of its range, also faces extinction due to declining habitat.
It is believed the Southern Hognosed Snake has already been extirpated from at least two states in its former range (Alabama and Mississippi) and has been placed in a Federal C2 listing for Florida. North Carolina is considering listing H. simus for Federal protection.
See the references below for more information

REFERENCES:

Linnaeus, C. (1766)
Systema Naturae per Regna Tria Naturae, Secundum Classes Ordines, Genera, Species cum Characteribus, Differentiis, Synonymis, Locis.
Tomus I. Editio duodecima, Reformata. L. Salvii, Holmiae

Thorpe, Tom. Project Simus. Presentation in Richmond, Virginia 11/2000.

Tuberville, Tracey. Research on Heterodon simus. Presentation at GTC, SREL Conference Center, South Carolina. 10/2000.

BIBLIOGRAPHY:

Blanchard, Frank A. 1939. A key to the Snakes of the United States, Canada and Lower California. Ann Arbor, University of Michigan Press.

Conant, Roger, and Joseph T. Collins. 1975 Reptiles and Amphibians of Eastern / Central North America. Houghton, Mifflin

Martoff, Bernard S., et al. Amphibians and Reptiles of the Carolinas and Virginia.1980. UNC Press. Chapel Hill, N.C.

Palmer, William M. and Alvin L.Braswell. 1995 Reptiles of North Carolina, The Unhifversity of North Carolina Press.

Platt,D.R. (1969)
Natural History of the Hognose Snakes Heterodon platyrhinos and Heterodon nasicus.
University of Kansas, Museum of Natural History, vol 18, No. 4, pp. 253-420.

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