Rare, "Weird" Snake Survives in Louisiana
for National Geographic News
|October 26, 2004|
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.
"When we've radio-tracked [the snakes], they are very closely associated with pocket gophers," Rudolph said. He noted that the snakes hibernate "within the gopher burrow system."
More gophers mean more snakes. But what else is it about a long-managed commercial timber property that the reptiles find so compatible?
"In the course of their operations [International Paper is] doing some things that are good for the snake. But none of us [scientists] know exactly what are these critically correct things that are being done," Reichling said.
For years the pine snake survived relatively unnoticed on the property. As its prevalence and importance has become clear, International Paper has set aside Louisiana pine snake management areas within its larger managed timber holdings. The goal in those special areas is to strike a balance between habitat and wildlife protection and with the intended commercial use of the property, according to company biologist Paul Durfield.
One tool is controlled fire, used to replicate the open forest and luscious ground growth that benefits both pocket gophers and snakes. A related initiative is the replacement of commercial loblolly pine with longleaf pine species that likely once grew on the site.
"Over the years a lot of the area which was historically longleaf pine has been converted to loblolly pine," Durfield said. "One thing we're doing is replanting longleaf in areas where the soil is conducive. Ecologically, longleaf pine allows you to burn the forest earlier. It's very fire adaptive, and you can run fire through a particularly young longleaf pine area."
The fire cycle may well help gophers and snakes, and not necessarily at the expense of International Paper's bottom line. Eventually the management areas will be harvested, which Durfield says can be done without compromising snake habitat.
"Longleaf pine does produce a very good commercial product," Durfield said. "It grows a bit slowly, but it makes a fine sawlog. So it will probably be grown on a lumber rotation, which is more like 25 to 30 years. Inside the management zone, when the longleaf reaches the point where it can be harvested, we can go in there and harvest those areas and still maintain the integrity of the site for pine snake. We'll be doing slightly different harvesting techniques in there, but we will still manage for fiber production."
The ability to juggle both could be key to the future survival of a unique reptile.
"Old-timers say, 'We used to see them in the '30s and '40s, but I haven't seen them in 30 years,'" Reichling said. "The younger people have no clue that there's such a weird snake in their midst. I try to tell them, 'You're sitting on a snake that's only found here.' It has been lost to their memory in just a couple generations."
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