At Sunshine Serpents, the Everglades rat snake has always been one of our specialties. The variety of questions that we receive about rossalleni leads us to believe that many in the herpetocultural hobby misunderstand this form. Their knowledge is based in internet rumors and popular perception rather than any real experience or research of the literature.
I (Daniel Parker) created an article called "In the Wild" on many of the captive breeding projects pages on our site. For the Everglades rat snake page, I thought it might be helpful to inform people on the natural history of the subspecies, present a point of view on its validity, and clear up some wide spread misconceptions. I have posted an excerpt below. Please see the link to our site at the bottom of the post for the full version with photos.
In the Wild-The Mythical Everglades Rat Snake
The Everglades rat snake has been the subject of controversy among herpetologists since its description. Its weak differentiation from the yellow rat snake E. o. quadrivittata drew criticism from many herpetologists, who did not consider it distinctive enough to warrant subspecies status. To confuse the situation even more, some have suggested that the conversion of the Everglades marshlands to sugar cane fields allowed neighboring yellow rat snakes to invade the area, genetically swamping the Everglades rat snake. The apparent rarity of rat snakes fitting the popular perception of rossalleni has given it somewhat mythical status among herp enthusiasts. Does the Everglades rat snake truly exist or did it ever?
The subspecies Elaphe obsoleta rossalleni was described by Wilfred T. Neill in 1949. He named it after his friend, the famous Florida reptile dealer and showman, Ross Allen. Allen founded the Reptile Institute at Silver Springs, FL. Through his collecting exploits, Allen was apparently aware of a distinctive form of rat snake from South Florida. As with several other notable Florida rarities such as the blotched king snake and the South Florida rainbow snake, he probably made Neill aware of its presence. Allen listed "Everglades rat snakes" in his catalog long before the subspecies was officially described by Neill.
Neill diagnosed the subspecies as follows:
A large snake allied to E. obsoleta quadrivittata, ground
color of adults rich orange, orange-yellow, or orange-brown; dorsal and lateral stripes present but not sharply defined, of a dull gray-brown shade; a vague sublateral stripe, evident posteriorly, on the tips of the ventrals; chin and throat bright orange; venter bright orange or orange-yellow; scales with a glaucous sheen, at least anteriorly; iris orange; tongue bright red. The diagnostic coloration is assumed at an early age; the smallest specimen examined, 605 mm. total length, was readily identifiable as rossalleni.
The new form was described as an inhabitant of the marshes, prairies, swamps, and hammocks of the Everglades and Big Cypress Swamp. A large percentage of this region is now agricultural lands. Sugar cane, sod, and corn fields are criss crossed by drainage canals.
Rodents abound on the canal banks and support a robust population of rat snakes. Despite a ready food supply, life is perilous for rat snakes as a host of predators, including several ophidian ones like the Florida king snake and eastern indigo snake, are always on the lookout for the next meal. Rat snakes may be found just about anywhere where they can get off the ground.
In an article in Herpetologica, Neill and Allen describe the microhabitats of E. o. rossalleni:
Many are discovered by night in the "Australian pine" trees (Casuarina equisetifolia) which have been planted along the highways in the area; others are found in roadside sheds, and also in the vicinity of bridges, where they secrete themselves in crevices between the road-bed and the bridge supports.
Years later, our observations have been exactly the same, though we have noticed that the larger specimens that have less to fear from predators are more likely to be found under cover objects on the ground or even basking on canal banks. We found a five foot Everglades rat snake stretched out under a metal I-beam (used to support the guard rails along roads) with two four foot Florida king snakes. This husky rat snake had nothing to fear from the smaller king snakes.
The wild rat snakes in the Everglades region today vary in color. They display a range of color varying from shades of brown to yellow and orange. Most specimens display distinctly lighter stripes than the yellow rat snakes from further north. By reading the above excerpt from the description, one should realize that there was some variation in the wild Everglades rat snakes at the time they were described. Even Neill's description of the type specimen did not really match his diagnosis for the subspecies. He described the head of the type specimen as being "mustard yellow" and the chin and throat as being "brilliant orange-yellow with an elongate white spot along the midline." In addition, Wright and Wright described the dorsal coloration of three specimens descending from south of Lake Okeechobee that were received from Ross Allen in 1949 with terms like "buckthorn brown," "tawny olive," and "sayal brown." None of these terms infers a bright orange dorsal coloration. None of the specimens that Wright and Wright examined had solid red tongues. They also describe the tongue of one specimen as being "red splotched with black."
Even today, rat snakes from South Florida are readily distinguishable from those from Central and North Florida by their lighter stripes and generally brighter coloration. Certainly Ross Allen would have recognized a distinct difference in the snakes from his home town of Winter Haven in Polk County, FL or his adopted home with which he is most associated, Silver Springs, FL in Marion County as compared with the snakes from south of Lake Okeechobee.
This author (Daniel Parker of Sunshine Serpents) has had the opportunity to follow in Allen's footsteps, having grown up near Winter Haven and now working on a field research project in Allen's former stomping grounds near Silver Springs. Our observations of rat snakes in the wild have led us to conclude that the rat snakes of South Florida are still distinct from those of Central and North Florida, though bright orange coloration might not be the most important characteristic. In our experience, only about 15-20% of the rat snake population south of Okeechobee is truly orange in color. However, many if not most of the rat snakes could be described as being orange-yellow, which seems to fit the description as far as we can tell. We would say that the rat snakes in South Florida are generally more colorful and have lighter stripes than specimens from farther north, be they orange, yellow, or somewhere in between.
Listening to people describe the snake they just saw in their backyard or the coloration of the snakes on a reptile show table makes one realize how subjective color perception is. Unfortunately, our observations are limited to the modern era and extensive studies of subjective color descriptions by dead herpetologists and the viewing of old black and white photographs will not eliminate all confusion. Anecdotes from field collectors in the 1970's and 1980's lead one to believe that the finding of a bright orange rat snake was an exceptional event, though that time period was also when much of the founding stock for today's captive Everglades rat snake bloodlines was collected. If you believe that Everglades rat snakes had already been genetically swamped at that time and "pure" examples no longer existed, than that would mean that the captive Everglades rat snakes we have today are just selectively bred yellow rat snakes. Hobbyists will continue to argue on internet forums about what makes a "real" Everglades rat snake and whether it still exists in the wild or even captivity. All this argument is of little concern to modern herpetologists, who lump all of the rat snakes east of the Appalachian Mountains and the Apalachicola River into the newly described Patherophis alleghaniensis with no subspecies described. Whatever theory you buy into, one thing is certain: The myth of the Everglades rat snake continues.
Link to Everglades rat snake page
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www.sunshineserpents.com
