FORT JACKSON, S.C. -- Josh Arrants and Samantha Smith, both wildlife technicians with the Directorate of Public Works Wildlife Branch, arrived at their first stop along North Tower Road at 9 p.m., Friday, under a first quarter moon. As they stepped out of their truck, they immediately heard the seemingly endless repetitive call of two Chuck-will’s-widows.

“That’s the first nightjar of the evening,” said Arrants, referring to a type of medium-sized, mostly nocturnal bird. “Looks like we may have a good count tonight.”

Smith quickly recorded the time, species heard and weather conditions as they both continue to listen for more calling nightjars.

Arrants and Smith were participating in Fort Jackson’s third annual nightjar survey. The primary objective of the survey is to contribute data to the Nightjar Survey Network, Center for Conservation Biology, at the College of William and Mary, Williamsburg, Va. This data helps determine the population distribution and trends of nightjar species across the United States.

Nightjars found on post include Whip-poor-wills, Chuck-will’s-widows, and Common nighthawks. Those participating in Friday evening’s survey counted the migratory birds by listening for their calls at 10 pre-established stations along a 10-mile set route.

Each route is surveyed one time per year during a very specific survey window. Participants spend six minutes at each station listening and recording the number of species and total number of nightjars they hear.

“These birds are mostly active in the late evening and early morning or at night, and feed predominantly on moths and other large flying insects,” Smith said. “Nightjars typically call more frequently when the moon is above the horizon or not hidden by dense cloud cover. That is why we survey on a clear night when the moon is visible.”

Nightjars are sometimes referred to as “goatsuckers” because of the mistaken belief that they suck milk from goats. This old wives’ tale is based on the birds’ very large mouths, which are used to catch flying insects in midair.

They have sensitive bristles around their mouths, like cats’ whiskers, that help them to locate prey, and are also thought to help funnel their prey into their mouths and away from their eyes.

In recent years, conservationists and the general public have come to share a general sense that populations of nightjars are dramatically declining.

Since 2007, data has been collected from more than 249 routes in 35 states by more than 400 volunteers. Prior to this survey program, there was no widespread or long-term monitoring effort of nightjar populations. Information gathered from the survey data will allow scientists to better develop conservation strategies for managing these bird species.

“The managed longleaf forests on Fort Jackson provide the perfect habitat for our three nightjar species,” Arrants said. “The large number of these birds present on our installation clearly shows the compatibility of the Army’s training missions and the management of forests that these birds depend on for survival.”