When Europeans first began settling the Texas Hill Country, the land was a mosaic of woodlands and prairie. Some areas were savannas, consisting of scattered live oak mottes in a sea of little bluestem and other grasses. 

Cedar “brakes”, consisting of impenetrable stands of Ashe juniper, were common in the rugged canyons. Open prairie often contained a mixture of shrubs and grasses. Bears, bison, white-tailed deer, pronghorn, mountain lions, and wolves were common. Fire shaped the landscape, creating a patchwork of habitats. The endangered golden-cheeked warbler and black-capped vireo benefited from this habitat diversity, since they depend on different successional stages of the various oaks and Ashe juniper that characterize the shrublands and woodlands of the area

Logging, overgrazing, and fire suppression changed the landscape. The reestablishment of this mosaic of habitats is what makes the Balcones Canyonlands National Wildlife Refuge so important.

Golden-cheeked warblers breed almost exclusively in juniper-oak woodlands. They require the shaggy bark of old juniper for their nests. These trees do not begin to produce shaggy bark until they are about 40 years old. From the 1950’s to 70’s, approximately 50 percent of the Hill Country’s juniper woodlands were cleared for pasture, and many canyons with golden-cheeked warbler habitat were inundated by reservoirs constructed for flood control.

But within the refuge are some old growth stands that are protected and managed for the golden-cheeked warblers. They are closely monitored to see if the birds are pairing, nesting, and successfully raising their young. This science is shared with many important partners who are part of a collaborative effort to ensure golden-cheeked warblers will always be part of the landscape.

The refuge’s low-growing shin oak is especially important for the black-capped vireo. This migratory bird prefers scattered clumps of oak shrubs separated by open grassland. Refuge staff periodically reset succession in shrublands to provide an abundance of the oak shrubs (shinnery) at the preferred height of six to eight feet. The goal is to ensure the shrubs are densely growing from the ground up. The nesting vireos prefer the dense foliage for their nests, which are built to hang within where they are hidden and protected.