The Center for Biological Diversity in Tucson and the Center for Snake Conservation in Louisville, Colo., have put up a $500 reward for evidence that the South Florida rainbow snake (Farancia erytrogramma seminola) is not extinct, as the U.S. Fish and Wildlife Service declared in October [pdf]. The organizations are hoping that professional and amateur herpetologists will keep their eyes and camera lenses open around Fisheating Creek in Glades County, Fla., the only site where the snake has ever been observed.

The South Florida rainbow snake is a subspecies of the more common (though itself on the decline) rainbow snake (F. erytrogramma), which can be found from northern Florida up through Delaware. The South Florida subspecies has only been officially identified three times, the most recent of which was in 1952. The photographs accompanying this article are of the only existing museum specimen, which is preserved at the Florida Museum of Natural History in Gainesville, Fla.

Even though confirmed South Florida rainbow snake specimens have not been found in nearly 60 years, anecdotal sightings have been reported, including some from biologists knowledgeable about snakes. Many herpetologists think the snake is still out there, waiting to be rediscovered.

It might not be an easy task, says Cameron Young, founder and executive director of the Center for Snake Conservation. "Rainbow snakes are fully aquatic and active mostly at night," he adds. "They're not something people would just come across. You need to go out of your way to find them or just be extremely lucky."

Several unsuccessful attempts to find the snake have been conducted since the 1950s, which the FWS cites as reason enough to not protect the species under the Endangered Species Act (effectively saying that if it could not be found, then it must not exist). But Young says that the previous attempts were not thorough enough. "To my knowledge, there's only been one effort to find the snakes with traps, and it was by someone who had never trapped aquatic snakes before." Young says it takes about 1,000 "trap nights"—for example, 1,000 traps for one night or 100 traps for 10 nights—to detect (that is, catch) more common rainbow snakes further north and that the previous attempt worked out to, at most, 150 trap nights. Even more trap hours might be necessary to find the South Florida rainbow snake.

Another reason the snake has not been seen, Young says, is that its river habitat was, until recently, mostly inaccessible to the public because it was surrounded by private cattle farms. This kept the river area pristine but limited survey efforts. The area is now accessible and "the opportunity to survey is now there," Young says.

The organizations acknowledge that offering a reward for evidence of the species' existence is "a bit of an unusual approach," says Collette Adkins Giese, herpetofauna staff attorney for the Center for Biological Diversity. "We're hoping it will prompt amateur herpetologists and others to get out and look for the snakes. If they're still out there, they're highly imperiled. If we can document them, we can get them protected under the Endangered Species Act."

Young says they do not want people going out of their way to catch a snake: "If you see one, it's likely to be basking on the riverbank while eating an eel or having just finished one." Eels are the snake's primary diet. "Take a photo of it. We don't have to have an actual snake." He says South Florida rainbow snakes are nonpoisonous and harmless, but the region is also home to more dangerous rattlesnakes and cottonmouths. The organizations' reward flier [pdf] offers additional tips on what to do and who to contact if anyone does find or observe one of the snakes.

Young admits that $500 is not a huge reward, but "it's an incentive for the people who are already there."

Meanwhile the Center for Snake Conservation is planning its own survey of Fisheating Creek in 2012 to try to find the snake. "We're going to give it our best effort," Young says. The organization is in the process of developing a plan and budget for the study and hopes to bring in several experts on aquatic snakes to assist with the search.

Photos © and courtesy of R. D. Bartlett