We all listen for certain sounds in the woods. Turkeys gobbling, bobwhite whistles, the drumming of a red-cockaded woodpecker, the squeak of a brown-headed nuthatch, or perhaps the song of the Bachman’s sparrow. As public and private land managers work to restore the open pine savannas of the Southeast, the need for efficient tools to identify prime restoration sites and monitor success is more pressing than ever. In a recently published study in the journal Ecological Indicators, Tall Timbers Stoddard Bird Lab Director Kate Richardson and her colleagues explored a high-tech solution: ecoacoustics.
An Autonomous Recording Unit (ARU) is installed at a study site. Skewers are attached to deter birds from perching on the unit, which would bias the ecoacoustic indices derived from the recordings.
The Promise of Ecoacoustics
Traditionally, assessing bird diversity requires experts to spend hours in the field conducting point counts. Ecoacoustic monitoring offers a “rapid assessment” alternative by using autonomous recording units (ARUs) to capture the “soundscape”—the collective biological, human-caused, and other natural sounds of an area. These recordings are then converted into numerical values called ecoacoustic indices, such as the Acoustic Complexity Index (ACI) and the Normalized Difference Soundscape Index (NDSI).
Putting the Tools to the Test
The research team deployed 18 Cornell Swift recorders across private lands in the Red Hills of Georgia and Florida. They recorded during the May breeding and January nonbreeding seasons to assess whether these indices could accurately reflect avian species richness and the impacts of management practices, including prescribed fire, supplemental feeding, and snag retention.
The results provided a nuanced look at the technology’s current capabilities. While the indices did not show a direct, significant relationship with total bird species richness or the presence of specific bioindicator species, they did reveal a complex story about how we measure forest health.
The Influence of Management and “Anthrophony”
Interestingly, although management actions such as supplemental feeding and prescribed burns were included, they did not have a significant standalone effect on the seasonal averages of the acoustic indices. Instead, the most consistent factor influencing the soundscape was “anthrophony”—human-caused noise such as road traffic.
On an hourly scale, the researchers found that ACI increased nonlinearly with human noise. This may suggest that birds in noisier areas may be adjusting their communication strategies by singing more frequently or more loudly to be heard over the din of traffic, which, in turn, changes the complexity of the soundscape.
Identifying High-Value Conservation Sites
One of the study’s most promising findings related to “site connectedness.” The researchers found that NDSI values were most consistent and precise at sites that shared a high number of species with other recording locations. This suggests that while these indices can’t count every species individually, they could help managers and conservation planners quickly identify sites with high conservation value that support a stable, interconnected avian community.
The Path Forward
This work marks a vital first step toward understanding how soundscape monitoring can support pine savanna restoration in the Southeast. Although ecoacoustic indices are not yet a “magic wand” for assessing species richness as a biodiversity indicator, they offer a powerful way to observe how seasons and human activity shape the acoustic environment. As researchers refine these tools, managers may soon have a new way to “listen” to the progress of their restoration efforts.
For more information, the full study by Richardson et al. (2026) is available in Ecological Indicators.
