for National Geographic News
The Louisiana pine snake (Pituophis ruthveni) is one of the rarest snakes in the United States. Yet the reptile is relatively abundant on a 30,000-acre (12,000-hectare) managed forest in Bienville Parish, Louisiana.
How did such an imperiled reptile thrive on a parcel long managed as commercial timberland? Scientists hope to learn whyand how to better manage the forest for both wildlife and timber production.
Old-timers in parts of eastern Texas and Louisiana recall meetings with what they call the "bull snake" as intimidating experiences. The colorful five- to six-foot (1.5- to 1.8-meter) snake often draws itself up off the ground when approached, hisses menacingly, and threatens a painful, though nonpoisonous, bite. Yet nowadays few people have encountered the animal, which has disappeared from much of its former range.
"It's a contender for the title of most endangered snake in the United States," said Steve Reichling, a biologist and curator at the Memphis Zoo in Tennessee. "This is a five- or six-foot snake that's diurnal [active in daylight hours] and should be relatively easy to find. Yet it's known by only about 250 documented scientific specimens since it was described in 1929."
The rare snake is found in only six isolated "islands" of habitat. (Most are in Louisiana, but a few are in Texas.) The largest and most important habitat by far is located on the Bienville Parish timber property managed by the International Paper company.
Reichling said ten of the snakes have been caught there since April 1. "That's an amazing abundance for this species," he added.
Gophers Feed Surviving Snakes
Much of the pine snake's scarcity is attributed to the loss of its sandy-soil, longleaf-pine-forest habitat. Logging, development, and agricultural conversion have largely eliminated the ecosystem from the region. Decades of fire-suppression activities have also greatly diminished the sunny, open nature of the remaining forest, which historically experienced natural, brush-clearing blazes on occasion.
Craig Rudolph is a research ecologist at the U.S.D.A. Forest Service Southern Research Station in Nacogdoches, Texas. He has been studying the Louisiana pine snake since the early 1990s. His working hypothesis suggests that the natural fire cycle, left unaltered in the past, was important to the snake's survival.
"On the west Gulf [of Mexico] coastal plain, fire is just not an ecological factor anymore," he said. "Because of suppression, [fire is] just too rare." Without natural fire cycles, areas that would normally be suitable pine snake habitat grow more woody, mid-story vegetation and fewer leafy-nonrigid plants at ground level, Rudolph said.
The absence of those green plants could mean a decline in pocket gopher populations, which appear to be the snakes' primary prey and key to the reptiles' survival.