ARU hearing Nightjars in your area?

by Sarah Manning, Coastal Conservation Coordinator

Autonomous Recording Units, also known as Acoustic Recording Units or ARUs, are an emerging technology that is beginning to help us understand more cryptic or difficult-to-detect avian species: ARUs have successfully been used to detect Black Rails and Northern Spotted Owls. ARUs can be programmed to record at selected times of day, over many weeks or months. This replaces the need for many hours in the field and provides more flexibility to collect data. While they are not yet able to replace a skilled field biologist or ornithologist, they are a great supplement and can provide valuable answers to various research questions.

Coastal Conservation Coordinator, Sarah Manning, installing an AudioMoth unit near Monticello.

Birds Georgia is utilizing ARUs to detect nightjars in Georgia. The Chuck-will’s-widow, Eastern Whip-poor-will, and Common Nighthawk are three species of nightjars found in Georgia. Nightjars are aerial insectivores and tend to be most active at dawn and at dusk, and on bright, moonlit nights. While Chuck-will’s-widows and Common Nighthawks range throughout the entire state, Eastern Whip-poor-wills’ breeding range excludes the coastal plain. Chuck-will's-widow numbers declined by about 1.6%, per year for a cumulative decline of approximately 58% between 1966 and 2019, according to the North American Breeding Bird Survey. 

Birds Georgia hopes to help fill in some of the data gaps for this species and create more suitable habitat to help these birds, and, as such, we have selected the Chuck-will’s-widow as our 2023 to 2025 Species of Concern. Birds Georgia is directing additional resources and expertise to the Chuck-will’s-widow – restoring native habitat, assisting with species-specific research, and engaging the public to help us better understand statewide population numbers and migratory behavior.

To do this, we are promoting the Nightjar Survey Network, formed by the The Center for Conservation Biology and coordinated by the Maine Natural History Observatory (MNHO) as part of the emerging Global Nightjar Knowledge Network. In addition to the Nightjar Survey Network, we are coordinating with the Georgia Department of Natural Resources (Wildlife Resources Division, Nongame Conservation Section) to coordinate survey routes and ensure statistical and scientific rigor. 

Volunteers are asked to survey one time per year, during late spring or early summer. Routes are nine miles with 10 stops, spaced one mile apart. Observers listen for Chuck-will’s-widows, Eastern Whip-poor-will’s, and Common Nighthawks over a six-minute period.  Data is recorded and shared with the Nightjar Survey Network, GA DNR, and the U.S. Fish and Wildlife Service. In 2024, we are on track to complete more than 13 routes – the most since the program began in 2007.

Our partner, Dr. Clark Rushing and graduate students at the University of Georgia Warnell School of Forestry are studying dispersal and migration of Chuck-will’s-widows along the coast by utilizing GPS tags. 

We are building off Dr. Rushing’s work by deploying these 15 Autonomous Recording Units (ARU’s) on private and preserved lands with differing management strategies with the goal of detecting which practices may yield better habitat for these nightjars. Private lands, greater than 10 acres in size, are encouraged to apply for our Habitat Stewardship Program. It is designed to enable property stewards to make improvements to their land for the benefit of native wildlife while also connecting them to educational resources, technical assistance programs, cost-sharing and revenue-generating programs, engagement and research opportunities..

Additionally, eBird and iNaturalist users are encouraged to report any incidental sightings of Chuck-will’s-widows, Eastern Whip-poor-wills, and Common Nighthawks. Complete reports and reports with photos, audio, or detailed comments are extremely helpful to learning more about this secretive summer singer. 

Birds Georgia has selected 10 sites for the placement of 15 AudioMoth units to assist us in learning more about the life histories of these birds (see figure 2). The sites chosen range from the barrier islands to the piedmont – reflecting the unique land uses and habitats in Georgia. Chuck-will’s-widows and Eastern Whip-poor-wills are known to occur within deciduous, pine (Pinus spp.), oak-hickory (Quercus-Carya spp.), and mixed forests. They also inhabit live oak (Q. virginiana) groves, forest edges, and riparian areas. Openings, including forest gaps, pastures, and scrub, appear to be an important habitat component for foraging, but comparative use of habitat types has not yet been studied in these species. Common Nighthawks favor more open habitat, including dunes, grasslands, fields, and can often be found in suburban areas near bright lights. 

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Figure 3. A Loblolly pine stand managed by thinning and burning. This site had burned two months prior. Can you spot the ARU? (Hint: It's on the far right of the image, attached to a pine with yellow paracord.)

From agricultural and pastoral fields to heavily-managed timber stands, our units were placed in areas with specified management criteria. We are interested in learning more about what land uses are compatible with these species, their habitat preferences, and what we may do to conserve these charismatic caprimulgidae (nightjars). 

For example, this Common Nighthawk nest (see Figure 4 below) was found 22 days following a prescribed burn. Common Nighthawks appear to respond favorably to prescribed fire, utilizing the newly barren ground to lay their eggs. Conversely, Chuck-will’s-widows have been found nesting in areas that burned 3 to 5 years prior, but not more recently. 

Units were deployed this spring and will continue recording throughout the summer and into early fall. Stay tuned for our pilot results - coming winter 2024. This work has been generously funded by the Georgia Ornithological Society Lydia Thompson grant. 

Figure 4. Common Nighthawk eggs - This site had burned just 22 days prior. The adult flushed off the nest and continued calling until I vacated the area.