Snakes on a plain
Ever heard of The Orianne Society? I hadn't either until I stumbled across their website recently while searching for "rattlesnakes" and "oil and gas development".
Founded in 2008, The Orianne Society is a relative newcomer to the wildlife conservation scene. Its mission: to conserve the world's rare and imperiled reptiles and amphibians.
The group's efforts are heavily focused on imperiled North American snakes. In fact, The Orianne Society got its start, and its name, when the young daughter of the group’s benefactor -- Dr. Thomas Kaplan, a philanthropist and founder of the wild cat conservation organization, Panthera -- had the chance to hold a threatened eastern indigo snake at a visitor center. Captivated, she asked her father if he could do for the snake what Panthera had done for the world’s most endangered cats -- pull it back from the brink.
What caught my attention when surfing their website, however, was the Society’s focus on viper conservation, and, in particular, their interest in the midget faded rattlesnake, a poorly-studied subspecies of the western rattlesnake that is restricted to the arid, coulee and canyon lands of western Colorado, Utah, and Wyoming.
As its name suggests, the midget faded is much smaller than its western rattlesnakes relatives and its rectangular, brown-and-buff patterning pales with time. And unlike prairie rattlesnakes, the midget faded is very specific to rocky outcrops and ledges, the cracks and crevices of which make perfect dens and hibernaculums for the small, shy serpent.
Like many western species, the midget faded and its habitat are increasingly threatened by grazing, recreation, and energy development. In 2009, to help protect the snakes (which are considered a Species of Greatest Conservation Need in Wyoming) from these pressures and guide future development, Stephen Spear -- biologist and assistant conservation scientist for The Orianne Society — and the Wyoming Department of Fish and Game teamed up with Clayton State University researcher Josh Parker to identify and map important midget-faded den sites and foraging areas in southwestern Wyoming and determine how those places are connected.
Using habitat and den models, Spear and Parker were able to identify 12 new den sites in the state's Little Mountain complex. They also collected genetic data to get a better sense of how roads —- whose tangled networks often accompany energy projects — may impact snake movement and gene flow between dens.
Their preliminary findings suggest that roads may effectively box snakes in, limiting their movement, breeding, and feeding options. Using blood samples taken from snakes from 12 different (but neighboring) den sites, Spear and Parker calculated the genetic difference between each den and compared that to a map of known roads in the area-- most of which are dirt--to determine gene flow. They were surprised to find that region's network of low-use dirt roads appear to be impacting the relationships between midget faded families. They were able to break the 12 dens into four distinct genetic groups, which suggests that mingling between dens is limited—a situation consistent with heavily-roaded areas.
The rocky rim habitat of the midget faded rattlesnake (Crotalus viridis concolor) in southwestern Wyoming. Photo taken by Stephen Spear.
Roads, therefore, may also prevent the snakes from reaching important feeding grounds -- which are often as far as a kilometer away from their dens -- where they hunt lizards and small rodents using a uniquely potent neurotoxic venom (most western rattlers have hemotoxic vemon).
If you looked at a map of Wyoming with the roads erased, you'd see a continuous range of snake habitat. Add roads back in, however, and you begin to see how roads may limit snake movement and lead to the creation of potentially critical corridors that connect midget faded den sites to foraging areas.
Given the West's mad rush for energy -- both fossil and renewable -- it's uplifting to know that groups like The Orianne Society are engaged in on-the-ground, collaborative research in the service of viper, key top-level predators in their rocky-rim habitats.
Spear and The Orianne Society plan to continue their work on the midget faded rattlesnake in Colorado this summer.
"To my knowledge," says Spear, "there really hasn’t been a lot of work on energy development and rattlesnakes, we really don't know that much yet."
Marian Lyman Kirst is an editorial fellow for High Country News.
Midget faded rattlesnake images taken by Josh Parker and used with his permission.