Bioacoustic Monitoring
Our Projects
Project Lead
Mike Turso
Introduction
The Meadowlands Research and Restoration Institute's acoustic monitoring program uses autonomous recording units (ARUs) to track wildlife populations, focusing on rare and cryptic bird species, bat species, and Atlantic Coast leopard frogs. This program aims to better understand biodiversity and population trends, particularly for these elusive species that are difficult to detect through traditional in-person survey methods. This enhanced ability to monitor these species helps inform and refine habitat management strategies, supporting the health of the Meadowlands ecosystem.
Atlantic Coast Leopard Frog Surveys
Atlantic Coast leopard frog, a recently discovered and highly localized amphibian species, occupies freshwater ecosystems across the Mid-Atlantic United States. Its specialized habitat preferences and fragmented range make it vulnerable to environmental changes. Despite its recent discovery, the species remains understudied, particularly in the New Jersey Meadowlands, where it is the last significant calling amphibian. This study aims to map the local distribution of the species, explore the environmental drivers of its vocalization behavior, and establish standardized methods for ARUs in monitoring. ARUs are deployed at potential frog habitats in the Meadowlands from late winter through spring. A custom-built Random Forest Model initially processes the audio data to identify frog vocalizations, achieving about 90% accuracy. Manual verification of detected calls ensures precision, while chorus activity is ranked on a modified scale to assess temporal and spatial trends. Environmental metadata, including air and water temperatures, humidity, and water levels, are compared against vocalization activity to identify potential correlations. Current results show that Atlantic Coast leopard frogs are present at multiple sites, including locations where their presence was previously undocumented. Choruses vary in size and temporal distribution, with peak activity associated with specific environmental conditions such as temperature and precipitation. The ARU protocol effectively captures seasonal calling activity and provides valuable insights into the species' vocalization ecology while minimizing human disturbance. This study underscores the utility of ARUs in long-term monitoring and conservation of the Atlantic Coast leopard frog and offers a scalable framework for similar efforts across its range. The findings enhance understanding of this secretive amphibian and contribute to broader bioacoustic monitoring practices for cryptic wetland species.
Publication of 2023 Study: https://www.eaglehill.us/urna-pdfs-regular/urna-073-Turso.pdf
Tidal Marsh Sparrow and Secretive Marsh Bird Surveys
Saltmarsh sparrow, a tidal marsh obligate endemic to the Atlantic Coast of the United States, faces a rapid population decline primarily driven by habitat loss due to sea level rise. This alarming trend highlights the urgent need for standardized, non-invasive monitoring methods to assess population dynamics and habitat use, particularly in highly developed regions such as the New Jersey Meadowlands. MRRI implements a passive acoustic monitoring (PAM) protocol using ARUs to detect saltmarsh sparrow vocalizations and assess their seasonal and spatial distribution. This study will also extend the PAM protocol to evaluate the distribution of other tidal marsh obligate sparrows and secretive marsh birds (SMBs), broadening its application across Meadowlands ecosystems. ARUs deployed at multiple sites record acoustic data during a controlled duty cycle throughout the spring and summer. Automated detection tools and pattern-matching analyses identify saltmarsh sparrow vocalizations as well as those of other species of interest. Vocalization patterns reveal site-specific temporal trends. Saltmarsh sparrows’ peak activity occurs in late May, likely reflecting a mix of migrants and breeding individuals. Hourly detection frequencies vary between sites, underscoring the importance of localized assessments in understanding vocalization ecology. This PAM approach effectively identifies presence and seasonal trends in saltmarsh sparrows, including at locations previously believed to be unoccupied. The methodology also demonstrates potential for broader bioacoustic studies, particularly in detecting SMBs in anthropogenically influenced environments. While challenges remain in estimating abundance and fully automating detections, this protocol offers a scalable, minimally invasive framework for long-term monitoring of saltmarsh sparrows and other tidal marsh specialists. Future applications will refine these techniques to support conservation efforts for these and other vulnerable marsh bird species.
Bat Diversity and Distribution Survey
MRRI biologists conduct acoustic surveys to assess bat diversity and distribution in the New Jersey Meadowlands. Using ARUs and autoidentification software, surveys have identified at least six bat species, including the federally proposed endangered tricolored bat (PESU). Big brown bat (EPFU) is the most commonly detected species, followed by eastern red bat (LABO), hoary bat (LACI), silver-haired bat (LANO), evening bat (NYHU), and PESU. The current results suggest that bats prefer upland capped landfills and forested habitats over salt marshes, likely due to limited foraging resources in the latter. Seasonal activity trends show consistent high use of forested and upland sites, with salt marshes exhibiting minimal activity. The most recent surveys reaffirm PESU detections at previously identified sites and have so far found one new location. These findings also suggest that PESU forages in a broader range of habitats than traditionally documented, including capped landfills. Validated PESU detections have been integrated into regulatory databases to support conservation planning under new federal protections. Differences in species detections between 2023 and 2024, particularly a decline in LANO detections, highlight the need for long-term monitoring to better understand habitat associations and temporal trends. Future objectives include expanded surveys to assess new sites with suitable habitats, reassessment of existing sites, and continued monitoring to establish seasonal and annual trends. These efforts aim to enhance our understanding of bat habitat use in the Meadowlands and to inform land-use decisions for this ecologically valuable region.
