Barton Creek meanders through Austin before emptying into the Colorado river, and for over seven miles the corridor along Barton Creek is a popular greenbelt with a hiking trail. The creek embodies some of the best of the Hill Country – clear water running over limestone rocks and boulders, cliffs with maidenhair and other ferns growing from crevices in the rock, and juniper woodlands with scattered oak and other trees. And up in those trees live Texas’ largest lizard, the Texas alligator lizard. Although they can grow to two feet in length (including the tail), they are so well camouflaged that most people never see them. The other delightful reptile commonly found in the greenbelt is the eastern black-necked gartersnake. This might arguably be Texas’ most beautiful snake, or at least one of the prettiest. Clint and I have visited the greenbelt several times in the past, finding these two species and several other delightful critters.
Austin loves its greenbelt, and it is lucky to have several small preserves and networks of nature trails. You could easily argue that such a big city could use quite a bit more than it has. With a population of 820,611, it ranks fourth in population among Texas cities. Evidently, many of those hundreds of thousands of people regularly visit the Barton Creek greenbelt, judging by Clint’s and my recent visit there. We arrived just before noon on a Saturday morning, met our friend Ruthann Panipinto, and headed down a break in the juniper woodlands to the trail that runs alongside the creek. Much of the Austin population was also running alongside the creek. And bicycling, and walking, and just seeming to be moved along en masse. It is a narrow dirt and rock trail, which we joined as soon as we found a gap in the parade of spandex and Nike-clad joggers, mountain-bikers constantly calling out to those in front so they could step aside, thirty-somethings with their dogs, and other folks.
We looked for any gap in the tangle of greenbriar, other vines, and tree saplings to escape the crowd, and used those opportunities to scan the leaf litter and rocky outcrops for gartersnakes, as well as trees above our heads for alligator lizards that might be draped along the branches. Were they here, despite the presence of all those people just a few steps away? Much of the wooded slope leading up and away from the creek is left alone by visitors, and it’s possible that wildlife become habituated to the nearby hikers if they rarely intrude beyond the screen of vegetation that borders the trail. We know that many animal species habituate to human presence, but how much does it vary by species and by size of the animal? To take one example, with repeated exposure to humans, alligators can “get used to” their presence, not fleeing when approached. However, not all species habituate to human presence, or not to the same extent. For the kinds of reptiles we were interested in, does it depend on how much disturbance occurs (can they begin to tolerate 1 hiker per minute, but not 40 per minute, for example), how close people are, and how often the disturbance occurs? We will have to leave those questions to the urban ecologists. We saw few reptiles and no amphibians, but it was the middle of an unnaturally warm October day, and there were millions of little hiding places, crevices in the rock, leaf litter, and piles of deadfall. Perhaps they were there, hidden.
We also dodged to the other side, to the creek bed, where it also seemed that visitors were uncommon. The clear water gently passed over the limestone rocks, as fish foraged around the bottom in graceful movements. A beautiful flame skimmer hovered, dipped, and darted around the area, and landed long enough for me to get a photo. These and other dragonflies are death on the wing for small soft-bodied insects that may be spotted by the dragonfly’s huge, wrap-around compound eyes. Like fierce raptors on cellophane wings, they intercept and snatch flies and mosquitos right out of the air. We watched this one for a while, and then returned to the trail.
Back on the trail, the crush of hikers and joggers continued. Those on mountain bikes often had to stop and wait for traffic to clear, and to their credit, the ones I saw were patient and thanked people when they got out of the way. Nevertheless, the effect of all this reminded me of crowded lines at the Six Flags Over Texas amusement park. Should I be delighted that so many Austin residents love to get outside in this semi-wild setting? It certainly would seem elitist for me to wish them away, restricting this place to my little group and excluding others. I spend some of my time trying to educate and inspire people, encouraging a love of nature. Was this the kind of outcome we would see if all nature educators were wildly successful? Can wild places be loved to death (or to some kind of sickness)? And can I separate the spoiling of my esthetic experience from the possibility of a place being harmed? That is, just because I was not able to experience solitude, peace, and the undistracted appreciation of nature does not necessarily mean that the place is being harmed. It might be, but I would have to use a different measure than my personal reaction to judge whether the habitat is being degraded and wildlife being harmed.
It was time to leave, and we reached the entry point and started to climb up toward the street. We stopped for a moment, and Ruthann stepped away from the moving river of people and into the woods. There, at the edge of a small ravine, she spotted it. Stretched out on a short branch was an eastern black-necked gartersnake, maybe 10 or 11 inches long and likely born last year. She called to us to come and admire this colorful little serpent with the orange stripe down the back and zig-zag black spots down each side, above a cream-colored lateral stripe. After taking a photograph of it just where it was, Ruthann captured it and we positioned it for some additional photos, and then Ruthann released it to resume its wandering in the greenbelt.
These gartersnakes are right at home along Barton Creek, where cricket frogs are common near the water’s edge and cliff chirping frogs are found along the limestone cliffs and outcrops. In my experience, these snakes are usually found close to a creek or some other water source, and this may be as much about diet as it is about the water and shelter offered by most wetlands. This snake is heavily dependent on frogs for its diet. A study by Fouquette (published in the Texas Journal of Science in 1954) provided information on the diet of gartersnakes found in Texas. Of the black-necked gartersnake, most specimens studied were the western subspecies, but it seems likely that the results apply to the eastern variety as well. Fouquette’s study reported that one specimen regurgitated a red-spotted toad. One preserved specimen contained a little brown skink (previously called the ground skink). All other stomach contents consisted of frogs, except for one slimy salamander.
After we left, Ruthann showed us another location with public nature trails, and this one was less crowded. There are records of alligator lizards from that locality, and Ruthann pointed out a spot where she sees a resident black-necked gartersnake from time to time. Maybe this will be the place for us to visit in the Austin area. Barton Creek has many visitors, and perhaps the way we can do our part is to not add our own presence to the hikers, joggers, and bikers making the weekend trek to the greenbelt.