Ecologist David Steen handles an Eastern indigo snake that had been reintroduced to Alabama, from which it disappeared in the 1950s. Photo: Cary Norton

Science

Snakes That Eat Other Snakes Could Help Birds in the South

By restoring the country's indigo snake population, scientists hope to bring balance to ecosystems—potentially benefiting songbirds.

David Steen slams the brakes of his black Chevy, bringing the truck to an abrupt stop on a sandy road in the Conecuh National Forest in southern Alabama. “That’s an indigo!” he says before throwing the truck into park, flinging the door open, and running out into the dappled November sunlight in hot pursuit of his quarry. Steen chases the indigo snake off the road and into the brush, where he catches it by the tail and lifts it up. More than three feet long, its shiny dark body curls onto itself like ribbon.

The country’s largest native snake, the Eastern indigo is an apex predator; it sits atop the reptilian food chain, eating the snakes that eat birds. Although indigos once glided through longleaf pines and sandhills from Florida to Mississippi, over time their habitat has been reduced—by development, agriculture, and fire suppression—to just 2.2 percent of what it once was. In the late 2000s, scientists began to reintroduce the snake in Alabama, where it had gone functionally extinct some 50 years earlier. Since then 137 have been released (plus another dozen last year at a second site in Florida). With the species making a comeback, other researchers began investigating the effect of that reintroduction on the food chain—in particular, songbirds.

Two years ago, Steen, then a research ecologist at Auburn University, helped set up more than 250 bird boxes to gather some much-needed baseline data. Because the snake disappeared so long ago, no one knew whether bird populations had declined in their absence—or how much they might rebound once the snakes returned.

So far, bluebirds, Carolina Wrens, Tufted Titmice, and Carolina Chickadees—as well as flying squirrels—have taken advantage of the new shelters. Finding an increase in box activity could mean fewer predators such as copperheads and rat snakes as a result of a robust indigo population.

But just as the project began showing promise, Steen was forced to pull the plug. There’s little appetite in the federal government for endangered-species research, he says, and money for the bird monitoring dried up. Steen left the snake-reintroduction work with Jim Godwin, a zoologist with the Alabama Natural Heritage Program. The project will continue for at least the next couple of years, with the release of roughly 30 snakes a year into Conecuh National Forest.

Conservation biologists also brought a dozen snakes to the Nature Conservancy’s Apalachicola Bluffs and Ravines Preserve in the Florida panhandle, the second reintroduction site. Here, Sara Piccolomini, a graduate student at Auburn University, monitors her charges as part of her thesis on the success of a new indigo snake population. She spends her days in the field searching out where they go, measuring them, and recording how they move among the wiregrass, bluestem, goldenrod, and longleaf pines. Support for her project came from a state program that collects money from specialty license plate sales that promote wildlife.

Unlike the snakes released at Conecuh, however, all 12 Florida-based snakes had implanted radio transmitters—and names. At the moment, Piccolomini is searching for Gail, an individual that appears to be on the other side of the ravine. The scientist expertly jumps over the trickling waterway and climbs the steep embankment on the other side, the slightest hint of sweat accumulating on her brow. After spending five to six hours in the field every time she sets out to track these snakes, she knows them and the terrain better than anyone else.

So far the snakes seem to be doing well. All of those Piccolomini has been able to track (two were found dead, another missing) are getting longer and heavier. She even saw one individual, Sally, eating a copperhead days after her release. The data has proved interesting as well. For example, it turns out that males and females disperse differently—a finding that could lead future conservationists to release females, which tend to stay put more frequently to get established. Tracing their movements could also reveal what the snakes need to thrive and how they behave in the wild.

The Florida project will at least last through next summer as Piccolomini shadows her indigos. After that, she’ll try to publish her work and move on to another area of snake study (she’s particularly into the effects of and resistance to venom). Before then, she hopes to witness another of her charges, maybe Jane or Val this time, swallowing a snake. 

“Throughout the region there’s still strong interest in what’s going on with the indigo snake,” says Godwin. “They’re going to be reshaping the snake community, which is going to have other effects.” If the snakes can successfully re-establish in the wild, chances are they’ll also improve conditions for bird populations across the longleaf pine forest. Hopefully, everyone will be able to see the results.

This story originally ran in the Spring 2018 issue as “It's a Snake-Eat-Snake-(Eat-Bird) World.” To receive Audubon magazine in print, become a member by making a donation today

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