A Talk on the Wild Side.
|Willow poles planted six feet deep in the bed to Terlingua Creek near the juncture with the Rio Grande. Photo by Jeffery Bennett/NPS|
Craig Springer of our Southwest Region tellsus about some amazing stream restoration work in west Texas.
The notion is as old as human experience—that people and places change over time. Heraclites reasoned 2,500 years ago that "Everything changes and nothing remains still and you cannot step twice into the same stream."
But you can try.
And try they are: Jeff Bennett, a physical scientist at Big Bend National Park in west Texas, is a specialist in hydrology, the science of how water moves on and under the land. He’s working in partnership with Mike Montagne, a fish biologist with the U.S. Fish and Wildlife Service stationed at the Texas Fish and Wildlife Conservation Office in San Marcos. Big Bend is in Montagne’s bailiwick. These two, along with other important partners, strive to recreate some semblance of the stream that was Terlingua Creek more than a century ago to improve fish and wildlife habitat, some of it essential for the conservation of threatened or endangered bird and fish species.
Terlingua Creek flows south out of the desert crags and canyons in Big Bend National Park, draining a 1,100 square mile watershed—an area only slightly smaller than Rhode Island. It is a very remote place—wild, preserved now for posterity in the National Park System. Yet the remoteness didn’t save the streamside woodlands from the far-reaching hand of man more than a century ago. Terlingua Creek once teemed with wildlife, its water purling through lush cottonwood and willow galleries that lined its course. The water was hidden from the blistering sun, cooled by the shade and slowed by beaver dams as it poured toward the Rio Grande.
But everything changed. The trees were harvested for firewood to fuel the nearby mining industries. That altered the creek’s course, its hydrology disturbed to the point that trees did not reproduce for lack of water. The timing and duration of creek flows changed, becoming unsteady, flashy. The water lost its shade and became not so suitable to fishes. Now, only about 40 percent of the 84-mile-long creek has permanent flowing water.
|Coyote willows planted in a diamond shape on Terlingua Creek are doing as intended. Note sediments deposted on the downstream side in the foreground. This is the foundation of an eventual willow and cottonwood gallery and makings of bird and fish habitats. Photo by Jeffery Bennett/NPS|
In a move toward making Terlingua Creek better for fish and wildlife, the partners planted scads of willow poles in February 2015 in a deliberate design, one to copy nature. “In our first phase we stuck 1,800 willows in five acres of gravel beds, deep, so that they would stay wet and root first then leaf out,” said Bennett. The willow poles were harvested from existing stands within the Terlingua Creek watershed and nearby Rio Grande, and planted in diamond-shaped patterns with a “spear” pointed upstream. “The shape mimics how groups of plants naturally arrange themselves against flowing water,” noted Bennett. “It seems to be working—the willows are five feet tall, green and catching sediment. That stabilizes the stream bank. The trees slow water movement—they’re like a sponge—sending more water to storage underground.”
And that of course is where you will find tree roots. These five acres and the stands yet to be planted in the coming years are future habitats for endangered birds like the yellow-billed cuckoo. It’s a bird obligated by its nature to nest in stands of established streamside stands of willow and cottonwoods. Gray hawks and common black hawks will also take to the galleries of willows and cottonwoods. Cottonwood trees are expected to naturally recolonize themselves in the protection of these new willow stands.
|Texas Fish and Wildlife Conservation Office biologists pull a seine in Big Bend NP looking for Rio Grande silvery minnows. Photo by USFWS|
And here’s another element of this conservation endeavor sure to take root, and that’s expanding habitat for the endangered Rio Grande silvery minnow. The fish was once found along the expansive reach of its namesake river and its larger tributaries. Today the Rio Grande silvery minnow swims the Big Bend reach and another limited stretch of river near Albuquerque, New Mexico. The silvery fish are there due to concerted releases from Uvalde National Fish Hatchery in Texas, and the Southwestern Native Aquatic Resources and Recovery Center in Dexter, New Mexico. Building more habitats is an essential conservation measure.
To take the Rio Grande silvery minnow off the endangered species list, some work needs doing, says Montagne. “Three separate, distinct, self-supporting populations of silvery minnows need to be established to down-list the fish. This site around Terlingua Creek and the Rio Grande in Big Bend is number 2,” said Montagne. “We planted silvery minnow in Big Bend from 2008 to 2012 and more fish came last fall.”
If anything is certain in the natural world, it would be impermanence. While Terlingua Creek will not anytime soon be like the pristine waters and wildlife habitat it was when cottonwoods towered over its banks more than a century ago, the partnership between the National Park Service and Fish and Wildlife Service is taking it closer. Nothing is everlasting but with perseverance on improving habitats, Rio Grande silvery minnow will swim its waters and the imperiled birds will return each spring to nest and fledge once again.