Audio: Sound of rattlesnake rattling.

There is no mistaking that sound. Most of us hear, "Danger!" "Stay back!" "Go away!" But University of Arkansas researcher Steve Beaupre hears something else: He hears the health of an ecosystem.

Beaupre: Rattlesnakes, in general, are low energy systems. We call them low energy systems because they're really well adapted to surviving on small amounts of food. So that makes them really good indicator species from a physiological standpoint. You can track a bunch of these animals an area where the habitat's being manipulated and if the food environment is improving for them, they will indicate that faster maybe than you can even measure changes in small mammal densities.

During the warm spring, summer and fall months, Beaupre and his graduate and undergraduate students spend several days each week in the Ozark Forest seeking out rattlesnakes and rodents to determine how these animals respond to changes in their environment.

Beaupre: I think it's down on the front end of this ridge down here. We'll probably have to walk down and hit the trail and head over that direction.

Beaupre studies rattlesnake physiology, looking at markers that help determine the health of the snake.

Beaupre: On this edge over here . I think a little further along this way .

He does this by trapping, tagging and radio tracking the snakes as they slither about their business in the wild.

Beaupre: He's right up in this . continuing on up here. Holly lucky stars . beautiful. Yep. I'm going to flip up around the back of him here.

This snake is one of many that Beaupre and his students follow.

Beaupre: We currently have about 25 of these snakes spread across the landscape here. These animals have a small radio tag surgically implanted in the back part of their body. It's about the size of the end of my little finger. We can then track the animal for two and a half to three years without any trouble. We get continuous information on them. We track them two to three times a week, weather permitting, and get continuous records on their movements, their habitat use, their body size and particularly their growth and physiological condition, their body condition. How fat they are relative to their length.

At the same time, graduate student Lara Douglas studies the effects of specific environmental changes such as fire and logging on the rattlesnake's prey by trapping mice, voles and other rodents to determine their population densities in the forest.

Douglas: The rattlesnakes eat almost exclusively small mammals and so looking at what happens to the mammal population should be associated with what's going on with the snakes. So our theory is that if mammal densities increase as a response to increased seed diversity or increased ground level food availability for the mammals, then the snakes should preferentially start foraging in areas where there are more mammals. And if they do that then they should be successful more often in their foraging attempts, and then they should, as a result, basically get fatter.

Beaupre: About five years ago, the game and fish commission approached us and said 'you know, we're going to cut and burn parts of this habitat to try to restore food availability coming in on the ground level . get more light to the canopy and activate some seeds in the seed banks to try to get more food production at ground level.' So Lara Douglas and I got together and we decided we would design an experiment where we had control sites, we had burn sites, we had cut sites and we had cut and burn sites. To compare those sites in terms of their vegetation structure, the small mammal densities and snake indicators of physiological condition, to see if those habitat manipulations would actually have the predicted responses on that food chain, on that three level food chain, that we thought were going to happen.

Over time, the information they gather will help create a more comprehensive picture of what happens when a forest burns or is cut down.
Beaupre: And we're getting nice responses, obvious responses in the vegetation communities. Dicey on and off responses of the small mammal communities . we'll have to kind of wait and see how that all comes out with the next trapping sessions. And strong indicators of snake performance improvements, including their body condition.

In the long term, Beaupre's studies also suggest that rattlesnakes can act as sensitive indicators of climate change.

Beaupre: As the seed production and productivity increase on the ground level, the turkeys, the deer, the squirrels, the small mammals and the snakes are all benefitting. The hawks and the bobcats are in on it too.

For these snakes, global environmental change is something to get rattled about. And that is something that scientists like Steve Beaupre want to listen to.

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