Influences of Borders on Golden-cheeked Warbler Habitat in the Balcones Canyonlands Preserve, Travis County, Texas




Sperry, Cynthia

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Destruction and fragmentation of breeding habitat threaten populations of many migrant songbird species, including the endangered Golden-cheeked Warbler. Fragmentation increases the proportion of habitat close to environmental borders, exposing flora and fauna in the bordering habitat to biotic and abiotic influences of the surrounding environments. I examined the influence of three types of bordering areas, a housing development, a utility easement, and woodland meadows, on several variables in Golden-cheeked Warbler habitat. I also examined the depth to which those influences penetrated into habitat. Type of bordering environment was an important factor in the extent of influence on habitat variables. Survey points near the housing development had lower detection rates for Golden-cheeked Warblers, more avian predator species, higher detection rates for avian predators, lower solar radiation, and higher sound levels than points near the other two areas. Golden-cheeked Warblers were detected with greatest frequency in habitat bordering the utility easement, which also had the greatest oak canopy cover and shin oak canopy cover. Golden-cheeked Warbler detections tended to increase with distance from edge and were negatively correlated with avian predator detections and sound levels, both of which decreased with distance from edge. I found no evidence that microclimate variables (temperature, relative humidity, wind, solar radiation) were influenced by bordering environments beyond the immediate borders. Preserve managers should be aware that Golden-cheeked Warblers may not fully use habitat within 200 m to 300 m from bordering housing and other intense human-use developments.



golden-cheeked warbler, conservation, habitat modification, Balcones Canyonlands Preserve


Sperry, C. (2007). Influences of borders on Golden-cheeked warbler habitat in the Balcones Canyonlands Preserve, Travis County, Texas (Unpublished thesis). Texas State University-San Marcos, San Marcos, Texas.


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