Dr. Amy Belaire
St. Edward's University, Wild Basin Creative Research Center, Austin, TX

Background

Wild Basin Wilderness Preserve is a 227-acre protected natural area located just 10 minutes from downtown Austin, Texas. With 3 miles of public hiking trails, it serves as a rare and accessible green space in an increasingly urbanized environment. In spring 2017, a biodiversity monitoring project was launched at the preserve, with a particular focus on avian species during their breeding season. The study was conducted by three St. Edward’s University student interns—Gabby Macias, Olivia Leos, and Anne-Marie Walker—under the mentorship of Dr. Amy Belaire.

The primary goals of the project were to:

• Monitor the impact of urbanization on bird and amphibian populations.

• Detect and map the presence of the endangered golden-cheeked warbler (Setophaga chrysoparia).

• Test and refine acoustic monitoring techniques in a real-world field setting.

Study Design and Methodology

To achieve its objectives, the team deployed Wildlife Acoustics SM4 Song Meter recorders using a transect approach:

• Transect Design: A straight-line transect was established perpendicular to Highway 360, extending deeper into the preserve along Bee Creek, a riparian corridor. This design was chosen to examine how anthropogenic (human-generated) noise from the highway influences wildlife presence and behavior.

• Acoustic Units: Three SM4 units were spaced ~300 meters apart along the transect. A fourth unit was rotated among various locations, targeting areas likely to be inhabited by the golden-cheeked warbler.

• Recording Schedule: Each unit was programmed to record one hour post-sunrise (to detect birds) and one hour at night (to detect amphibians such as frogs and toads).

• Calibration: Before deployment, all recorders were calibrated using pink noise in the University of Texas's anechoic chamber. This ensured consistent data quality across all units.

• Anthropogenic Noise Measurement: An iPad with an external microphone was used to measure noise levels along the transect, capturing baseline data on urban soundscapes.

Field Implementation and Observations

The project combined hands-on fieldwork, data analysis, and skill development in acoustic ecology:

• Testing and Training: Interns field-tested the units by playing recorded cardinal calls at different distances and analyzing spectrograms using Kaleidoscope software. This software grouped similar calls into clusters to facilitate identification.

• Songbird Identification: Students trained using online tools like the Cornell Lab’s Bird Song Hero and mobile bird ID apps to recognize and categorize calls by ear—skills they later used to verify software-generated clusters.

• Urbanization Gradient: By placing recorders from a high-traffic area near the highway to quieter interior habitats, the team began identifying shifts in bird presence and behavior along the urbanization gradient.

Key Findings and Insights

• Successful Detection of Golden-Cheeked Warblers: The rotating fourth unit proved effective in detecting the elusive and endangered golden-cheeked warbler, confirming that the species continues to breed within Wild Basin.

• Multiple Species Detected: The SM4 units detected a wide variety of songbirds including Northern Cardinals, Carolina Wrens, Blue Jays, and others. Kaleidoscope software enabled sorting and long-term tracking of individual species’ presence.

• Noise Influence Observed: Preliminary analysis suggested that species richness and vocal activity decreased near the highway, highlighting the potential impacts of urban noise pollution on wildlife.

• Enhanced Awareness and Education: Interns reported a dramatic increase in awareness of bird sounds in their daily lives, turning background noise into a meaningful aspect of the natural world.

Conclusions

This project demonstrated the effectiveness of acoustic monitoring in assessing biodiversity in urban-proximate natural areas. It also served as a powerful learning opportunity for undergraduate researchers, providing hands-on experience with fieldwork, calibration, spectrogram analysis, and bioacoustic interpretation.

Notable takeaways:

• Passive acoustic monitoring is a low-impact, scalable method for tracking wildlife in sensitive habitats.

• Student involvement in citizen science contributes meaningfully to both conservation and education.

• The transect design offers valuable data on how urban pressures influence species distribution over short spatial gradients.

• Data collected has laid the groundwork for long-term monitoring of avian and amphibian communities in Wild Basin and other urban preserves.

Future Directions

• Expansion of monitoring to include seasonal variations and additional taxa (e.g., bats, insects).

• Development of a long-term acoustic database for trend analysis.

• Public engagement initiatives using citizen science apps and acoustic stations to connect urban communities with local biodiversity.