The park is home Rio Grande turkeys, eastern bluebirds, golden-cheeked warblers, black-capped vireo and other migratory birds. Native white-tailed deer and exotic axis deer wander the forest, along with the small animals of the Hill Country – squirrels, rabbits, racoons and armadillos. The hills, steep canyons and river valley abound in mesquite, Texas redbud, bald cypress, western Ashe juniper, Spanish oak, lacey oak, Texas madrone, cedar elm and pecan.
The highlight of the park is the Frio River, which runs clear and cold through the shade of grand cypresses, rushing over the shallows into deep pools. In the fall, its blue and green waters contrast with the bright orange and yellow of the autumn leaves.
The park’s interpretive guide explains its unusual geology:
Located on the southwestern edge of the Edwards Plateau, Garner State Park is part of a unique natural subregion known as the Balcones Canyonlands. Edwards limestone uplifted millions of years ago to an elevation of 2,000 feet, creating steep canyon walls and some of the most spectacular views in the Texas Hill Country. The canyons angle southeast to northwest, taking advantage of the southeast prevailing winds to cool and moisten the area. This allows more diverse vegetation to thrive in this arid region of Texas. The rugged terrain protects many vegetation communities, including Ashe juniper, oak and cypress, as well as a small population of endangered Tobusch fishhook cactus.
Six miles of hiking trails wind through the park’s 1,400 acres, climbing up steep hills and down into the adjoining canyons. In addition to spectacular views of the Frio River valley, the highlights include two small caves. In the winter, a walk along the Frio River by the Oakmont camping area is one of the most picturesque areas of the park.