Longleaf pine forests and gopher tortoise burrows perfect habitat for threatened species

It was Monday morning and Tropical Storm Ida was welcoming us to the new week. As the early chills of fall enveloped us, dark clouds gathered in the distance, ominously blocking out the sun. Perhaps seeing the look of concern on my face, Dirk Stevenson consoled me,

“No worries, the indigos won’t mind.”

Dirk is the Director for Inventory and Monitoring for Project Orianne, a large non-profit organization dedicated to conserving the eastern indigo snake where they remain and restoring populations to areas where they have disappeared. Dirk was to be my field companion for the day, accompanying me to my field site in the Florida panhandle. He hoped to establish whether indigo snakes, often locally known as gopher snakes, still persisted in the area, despite the lack of a confirmed sighting in over ten years.

Indigo snakes once roamed throughout the southern half of Georgia through Florida and west to Mississippi. Today, however, they may be found only in isolated and relatively undisturbed areas and they’re thought to have disappeared entirely from both Mississippi and Alabama. Although one of the largest snakes in North America (they can reach over eight feet long) and a fierce predator (including of rattlesnakes), the species is surprisingly vulnerable to changes to its habitat. As a large animal, it requires a large area to survive. An indigo snake living near humans is vulnerable to being killed on roads or by domestic animals. Its docile nature made it a popular target of collectors who wanted to make pets of the giant beasts.

Perhaps the most insidious threat to the continued persistence of the indigo snake in the southeast relates to the population decline of another species altogether, the gopher tortoise. Gopher tortoises are considered keystone species, meaning their presence influences many other organisms in their shared habitat. Tortoise burrows are used by a wide variety of other animals, notably the indigo snake. Indigo snakes use these burrows as shelter during very high or low temperatures and may search through them to find potential prey. They may be used for nesting, for mating, or to fight rivals. In some areas where they can both be found, tortoise burrows are an integral component of the landscape for indigo snakes.

Tortoises have declined for a number of reasons; historically they were harvested intensively by hungry humans. But that this practice has been outlawed doesn’t mean tortoises are in the clear. They prefer pine forests with few trees, an open canopy allows a lot of sun to reach the ground and encourages growth of the plants they like to eat. To keep pine forests open, however, requires fires to burn through every couple of years, as they did in the past after lightning strikes. These fires keep hardwood trees from becoming established in the forest, when they would otherwise crowd out pine trees and block out the sun. Many southeastern forests haven’t been exposed to fire in a long time, making the habitat unsuitable for gopher tortoises, which reduces the amount of refuges available for indigo snakes.

When it comes to indigo snakes, the Florida panhandle is a head-scratcher. Although the number of gopher tortoises in the area is considerably lower than elsewhere, they are still hanging on. And in this region can be found some of the most expansive longleaf pine forests remaining in the world. It would seem as if the area was tailor-made for a healthy population of indigo snakes, yet it’s been a decade since they were last spotted.

As we drove to the first site, a secluded area where you can still find a small number of tortoise burrows if you know where to look, Dirk explained the unusual behavior of the indigo snake. In the fall, on days when most other snakes would be holed up for warmth, male indigo snakes are conducting serious business; that is, looking for females. These males will crawl throughout the forest searching for either other snakes or the tortoise burrows they might be hiding within. It was our hope we might encounter one of these giant serpents as it undertook one of these excursions or perhaps a female coiled up and basking in the sun outside a burrow.

I couldn’t help but hope we found an indigo snake, a species that has successfully eluded me so far. I knew it was a tall order to see a federally threatened animal in an area where they haven’t been found in a decade, but I would’ve settled for seeing a large track in the loose sand leading down to a tortoise burrow.

This would indicate to us that an indigo had traveled through recently and give us some reason to be optimistic for the species’ recovery in the region. If they were still clinging on, the site might be considered a suitable spot to introduce more snakes, in the hope they would interbreed and thrive.

In short order, Ida started threatening us again, now with the beginnings of the rain that would drench the region throughout the night. Despite the less than ideal conditions, we dutifully visited sites we thought held the most potential, walking through the woods looking for the disturbed soil that might indicate a tortoise burrow. We were disappointed though, to find that even in areas where you could find dense populations of tortoises only years ago, they were few and far between now. Without burrows to serve as targets for our search, finding an indigo snake was like finding a needle in a haystack, if they were even there at all.

Living alongside wildlife is a column by David A. Steen. David is a Ph.D. candidate at Auburn University and researching amphibians and reptiles in the Walton County area. To learn more about David and his work, go to:
www.davidasteen.blogspot.com