Wildlife Diversity Program Quarterly Report for July–September 2025
MICHAEL FOGLEMAN
Chuck-will’s-widow with nestling, Harris Game Land, Upper Boat Ramp.
Autonomous Recording Units … Working All Night Long … by John Carpenter, Coastal Region Landbird Biologist; and Silas Hernandez, Assistant Coastal Region Landbird Biologist
A utonomous recording units (ARUs) are small, portable devices designed to passively record surrounding environ- mental soundscapes, including bird, frog, and even high-fre- quency bat calls. They are gaining immense popularity due to their increasing ability to accurately document species occur- rences via machine learning of their vocalizations. In addition, they can be conveniently programmed to record at only certain times of the day and for weeks or months at a time, thus work- ing tirelessly in hard-to-reach places and at difficult times, for example at night, when conditions may be more hazardous to field staff. In early 2025, the WRC Coastal Landbird Team initiated a pilot project to determine if ARUs could help assist with the NC Bird Atlas, and more specifically, to document three primarily nocturnal species: the Common Nighthawk (Chordeiles minor) , Chuck-will’s-widow (Antrostomus carolinensis) , and Eastern Whip-poor-will (Antrostomus vociferus) . These eccentric species, often referred to collectively as “nightjars”, return to NC from their Neotropical wintering grounds at the end of March. All three can be heard from dusk to dawn in open forests, forest edges, and fields. Despite their obvious vocal behavior, they are difficult to spot and observe during the day, which is when most Atlasers are out looking for birds. Not surprisingly, nightjars currently lack accurate population data, which is necessary to
help guide conservation initiatives and prevent future popula- tion decreases. From April to July 2025, we systematically deployed an aver- age of 25 ARUS at a time, typically 5 units per Atlas survey block (3x3 square mile), and programmed each to record intermittently from dusk until dawn. In total, we collected data in 15 Atlas sur- vey blocks, most of which had little to no nocturnal survey effort,
on public and private lands throughout the Coastal Plain. To date we have verified recordings of 260 singing nightjars (one example available here), as well as non-fo- cal species such as Barred Owl and Eastern Screech Owl. These recordings helped demonstrate the persistence of singing males at each site, thus
allowing us to elevate all three nightjars to “Probable” breeders in nearly 70% of sampled Atlas blocks! These results, while still very preliminary, have shown that ARUs can help support the objectives of bird atlases.
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