What is Happening to our Southern Hog-Nosed Snake?

Authored by Matt Moore

North America’s Hog-nosed Snakes (genus Heterodon) have always been my favorite snakes since I was a little kid. In fact, the very first snake that I ever caught was a Hog-nosed Snake when I was a small child. This is one of my earliest memories from childhood: it was the early 1980’s and our family had recently moved into a new house on the edge of a sandhill in South Georgia. I was playing in the backyard one day when I saw the back end of a small snake crawling under a shrub next to the house. I did exactly what no one should ever do when I reached down and picked up the unidentified snake and brought it into the house. It turns out that I was lucky and had picked up a harmless snake…a Hog-nosed Snake! My memory is not vivid enough to be completely certain as to whether it was an Eastern or a Southern Hog-nosed Snake, but based off a combination of what I do remember of its coloration/pattern and my parents’ recollection that it had a sharply upturned nose, I suspect that it was very likely a juvenile Southern Hog-nosed Snake.

Georgia has two native species of Hog-nosed Snakes: Eastern Hog-nosed Snakes (Heterodon platirhinos), which also range throughout much of the eastern half of the United States, and Southern Hog-nosed Snakes (Heterodon simus), which are endemic only to the Coastal Plain of the southeastern United States. For reasons still frustratingly unknown, the Southern Hognose Snake has experienced a drastically disproportionate decline throughout much of its range over the last 40 years in comparison to its larger relative the Eastern Hog-nosed Snake. The Orianne Society has actively surveyed for Southern Hog-nosed snakes over a multi-year period in Georgia, and based off of our survey results, we are very concerned for the future of this species.

Eastern and Southern Hog-nosed Snakes are known for their elaborate bluffing defensive behaviors that they often employ when encountered in the field. Eastern Hog-nosed Snakes, in particular, have evolved the most dramatic defensive repertoire out of all the species within the Heterodon genus. When they feel threatened, Hog-nosed Snakes will often display some combination of the following behaviors: laterally spreading their necks out very wide (in an appearance very reminiscent of Old World Cobras), hiss loudly, inflate their bodies with air or conversely flatten their bodies out very wide, flatten their heads out into a pronounced triangular shape, feign strike (neither Eastern nor Southern Hog-nosed Snakes ever actually bite in self-defense), gape open their mouths, and coil their tails into a circular or cork-screw shape. These intimidating defensive behaviors are all just elaborate bluffs that these snakes have evolved to ward off perceived threats. However, if these impressive defensive tactics fail to deter a perceived threat, these snakes will often roll over onto their backs and play dead (a behavior known as thanatosis) with their mouths wide open and tongues hanging out. Upon initiating thanatosis, these snakes will often regurgitate recently eaten toads and writhe around as if in the throes of death while simultaneously excreting copious amounts of feces. Unfortunately, the intimidating/bluffing defensive behaviors that Hog-nosed Snakes often employ when they feel threatened has led to the deaths of thousands of these harmless snakes every year by people who mistakenly believed that they had encountered a dangerous snake.

It has become disturbingly clear that Southern Hog-nosed Snakes have suffered a disproportionate decline in comparison to the other upland snake species that are also in decline in the Coastal Plain of the southeastern United States. Southern Hog-nosed Snakes have been completely extirpated from Alabama and Mississippi since the 1970’s and have become extremely uncommon throughout much of their remaining range in the Coastal Plain of the southeastern United States. Southern Hog-nosed Snake populations in Georgia appear to have been reduced to just a few small and highly fragmented populations throughout the lower to middle coastal plain. However, they seem to be doing somewhat better in the upper Coastal Plain of Georgia. Southern Hog-nosed Snakes are found much more frequently throughout much of Georgia’s upper Coastal Plain and thus appear to be indicative of relatively larger and less fragmented populations in that portion of the state.

Southern Hog-nosed Snakes have seemingly disappeared entirely from large areas of the Coastal Plain of Georgia that still contain relatively large tracts of well-maintained suitable habitat. However, confoundingly, individuals of this species will occasionally still turn up in some highly fragmented patches of “habitat” in heavily developed residential neighborhoods in some isolated areas within their range. One plausible, albeit difficult to test, proposed cause of their disproportionate decline is Red Imported Fire Ants (Solenopsis invicta) from South America. It may very well be more than just mere coincidence that Southern Hog-nosed Snakes have been completely extirpated from not only Alabama, the exact state where these ants were first introduced, but also from adjacent Mississippi too. Georgia, also adjacent to Alabama, appears to be suffering more severe declines of Southern Hog-nosed Snakes than states at the far periphery of their range (i.e. central Florida and southeastern North Carolina). After first reaching shore in Alabama in the first half of the 20th century, these ants have spread throughout the southeastern United States like a stinging plague and have caused incredible amounts of damage to ecosystems in the areas where they have become established.

It is possible that Southern Hog-nosed Snakes are particularly susceptible to predation by Red Imported Fire Ants. Lower clutch sizes, due to the comparatively smaller size of adult female Southern Hog-nosed Snakes in comparison to adult female Eastern Hog-nosed Snakes, may have led to lower recruitment in Southern Hog-nosed Snake populations due to predation of their eggs and hatchlings by these ants. Red Imported Fire Ants being the causative agent in the disproportionate decline of Southern Hog-nosed Snakes is still relegated to mere speculation at this point, but it does seem plausible that they could very well be the culprits behind the plight of this snake species.

The Orianne Society is very interested in documented sightings of Southern Hog-nosed Snakes. A clear photo, location, and the date of the sighting of any suspected Southern Hog-nosed Snakes is very much appreciated from citizen scientists who would like to help in our attempts to aid this species. It is important to note that Southern Hog-nosed Snakes can look very similar in body coloration/pattern to some juveniles and small adult individuals of the highly variable Eastern Hog-nosed Snake. However, they can be reliably differentiated by a comparison of the rostral scales (i.e. “noses”) of these two snake species. The rostral scale of Southern Hog-nosed Snakes is much more sharply upturned than the rostral scale of Eastern Hog-nosed Snakes. Please send in your sightings of suspected Southern Hog-nosed Snakes found in Georgia to the Orianne Society to be added to our database so that we can document where this species is still hanging on in our state. Mid/late Spring and early/mid Fall are the ideal times to look for this species in Georgia. Adults and juveniles are often seen during the usual Spring spike in their activity and all age classes (hatchlings, yearlings, adults) are likely to be encountered during the usual subsequent Fall spike in their activity following a period of relative dormancy through the hot summer months. Any documented sightings of Georgia’s rare and declining upland snake species sent into us by citizen scientists are very helpful and very much appreciated!

Fast forward 35 years or so later after finding my first snake under that shrub in the back yard and I find myself here writing about Hog-nosed snakes for The Orianne Society’s newsletter. If that first snake that I ever caught all those years ago was indeed a Southern Hog-nosed Snake, then it is still the only live one that I’ve ever seen in the wild. Despite years of active searching during the peak times of the year when this species is most active, thousands of miles driven, many miles hiked, and seeking out known areas where this highly elusive snake is still known to persist, I have yet to find a single Southern Hog-nosed Snake. I have not given up, but this journey has been eye opening in illustrating just how uncommon and elusive this snake has become throughout much of its endemic range within the Coastal Plain of the southeastern United States.