The Barton Creek watershed is alive. Walk along Barton Creek and you’ll hear the calls of mourning doves and the rhythmic tapping of woodpeckers. You might see a blaze of crimson as a cardinal glides among the live oaks and cedar, spot a red-tailed hawk hunting its next meal, or chuckle at the sight of a squirrel bounding from limb to limb. In spring, you’re surrounded by patches of fragrant bluebonnets, Indian blankets and delicate buttercups.
Each of these living things is like a cell in a human body; each species, an organ. Destroy one cell, and the body recovers. Destroy one organ, and the body is damaged, perhaps beyond repair.
Like the human body, the ecosystem nestled among the hills of southwest Austin is dynamic and hardy. It changes over time. Variations in climate might force one species to leave the area, but another will find the new conditions quite hospitable. It can resist some tampering from the outside, with the delicate balance among species shifting to maintain the overall health of the ecosystem. Yet too much tampering – polluted water, increased soil erosion, more pavement or the introduction of a ferocious new organism (such as the fire ant), can ravage the ecosystem.
Today, the area still is a naturalist’s dreamland of hundreds of species of plants, mammals, fish, reptiles and invertebrates. Some are found no farther west than Austin. Some are quite rare. A few are found nowhere else on Earth.
A cursory glance at the area delivers one overwhelming impression: green. The hills are thick with many species of oaks and elms, as well as ash juniper (better known as cedar) and hackberry. Open areas are covered with wild grama or bluestem grasses. Creekbeds and springs are surrounded by cottonwood, pecan, elm, willow, chinaberry, redbud and many other species of trees, along with an abundance of shrub and wild-grass species. Each of these plant species harbors birds, mammals and insects.
Among the many plants that live in the creeks and springs are a variety of ferns, coontail, water primrose, wild celery and cattail.
Of course, the water in Barton Creek and other creeks, springs and ponds is the centerpiece of life in the area, sustaining the deer, rabbits, bobcats, foxes, raccoons, field mice and other mammals that inhabit the rocky countryside. It’s home to frogs and turtles. Fish and insects living in creeks and ponds attract myriad species of birds, from great blue herons to spotted sandpipers.
It’s obvious, then, that each portion of the ecosystem depends on other parts for survival and population control. If the bobcat and predatory birds that inhabit the region disappear, populations of small mammals could run wild. If one clump of trees is destroyed, some critical habitat for a bird species may be affected.
For example, the golden-cheeked warbler inhabits steep canyons in part of the Barton Creek basin. Because it uses cedar bark that is more than 20 years old to make its nests, when mature cedar woodlands are destroyed, the species has nowhere to nest and rear its young — and could face extinction. The warbler also faces danger from the cowbird, which lays its eggs in the warblers’ nests, displacing the warbler chicks.
Several other rare or endangered species inhabit the basin. Two species of eyeless arachnids, called harvestmen, are found in the caves on Barton Creek, along with at least four other rare invertebrates. Barton Springs itself is home to two rare, blind snails, and a two-inch long salamander first seen in Barton Springs Pool in the 1940‘s is unique to Barton Springs. There are also rare plants in the basin. The endangered bracted twistflower is found infrequently on rocky wooded slopes in the upper reaches of Barton Creek.
The wildlife of Barton Creek
Travis County has many endangered species because it is a crossroads of several distinct ecosystems – the Edwards Plateau, the Blackland Prairies, the Crosstimbers and the Prairies. A transition zone, the Balcones Canyonlands, lies west of the Balcones Fault Zone, which runs north—south through Austin. Canyons and mixed woodlands of ashe juniper (cedar) and oak separate the Blackland Prairie from the Edwards Plateau to the west. Many areas are “karst” terrain, which contains caves, sinkholes, and other solutional features.
The rare species have survived many climatic changes. The climate was cooler and wetter long ago, but when it dried out, some species were left stranded on limestone hills, in caves or in cool canyons. These isolated species evolved into distinct forms adapted to their specific habitats. This is especially true of the numerous cave species, which are isolated in cave islands within the limestone. Many cave species have lost their eyes and pigment over thousands or millions of years.