On a warm and buggy May evening, an Eastern Whip-poor-will’s brown, orange, and white mottled feathers blend in seamlessly with the brittle oak leaves she sits on. The bird is nearly impossible to differentiate from her surroundings. Grant Witynski, a biologist at the University of Illinois Urbana-Champaign, stands just a few feet away. As he and his technical assistant Olivia Moline inch closer, a stick snaps under foot. The bird flushes to a nearby branch just above the ground, her wings outstretched in defense, her flat head and whiskered face opposite her offenders. In the shallow indentation where she sat are two brown marbled eggs, the first seen by researchers this season.
Witynski is part of an ongoing project to monitor whip-poor-wills in Central Illinois’s Sand Ridge State Forest, where prickly pear cacti lobes erupt from the ground and oak trees tower over patches of prairie. This study site is one of the few known places in the Midwest where the birds, one of several declining species in the nightjar family, thrive—and ornithologists are trying to figure out why. Survey data and personal accounts suggest that populations of Eastern Whip-poor-wills, Common Nighthawks, and Chuck-will’s-widows are falling throughout their ranges, but the reasons remain largely a mystery.
“There are still enough out there that if we figure out what’s going on, we can probably turn around that trend pretty quickly if we do the right thing, that’s our hope,” says Mike Ward, an ornithologist and Witynski’s advisor at the University of Illinois.
Camouflaged, nocturnal, and elusive, nightjars are some of the least-studied birds on the continent. Whip-poor-wills, which breed throughout the Midwest and eastern United States, are perhaps the best-known species of the group, their characteristic whip-poor-WILL song celebrated in songs and folklore. These enigmatic nightjars sing most often in the late spring and early summer to find mates and defend their territories—but not as frequently unless the moon is full. This behavior makes them especially difficult for researchers and volunteers to locate most evenings. During the day, the birds rest motionless on a branch or the ground, taking wing at dusk to feed on moths and other insects illuminated by moonlight.
In recent years, a growing number of ornithologists have begun to uncover more about nightjars thanks to technological advances like GPS backpacks and satellite telemetry. Growing concerns about the family’s decreasing numbers even led to the formation of the Nightjar Global Network, an informal group that holds an annual conference on recent research. In the Midwest, monitoring and tracking efforts underway help ornithologists find where Eastern Whip-poor-wills, or “whips” as they are affectionately called, flourish and figure out what’s happening on their wintering grounds in the southern United States, Mexico, and Central America. Such information is critical to protecting the birds and their nightjar relatives as agriculture, development, forest management, and climate change affect their ability to survive across their range.
“Whatever you do to help whip-poor-wills is probably going to help a lot of other birds and probably other types of wildlife,” Ward says.
Observing nesting whips is just one part of Witynski’s nightjar work led by Ward and T.J. Benson, another ornithologist at the University of Illinois. The pair began their efforts in 2008 when they founded the Monitoring of Owls and Nightjars (MOON) project. Every year for the last decade and a half, volunteers in the state have gone out twice during the summer. They stop on the side of the road and listen for whips and owls, data that helps researchers assess population trends over time. When Ward and Benson evaluated the surveys, they saw that in places where whip-poor-wills had once called, there was no evidence of them years later. Entries from eBird—or lack thereof—provided more evidence of falling whip and other nightjar species’ numbers.
“That really got me very concerned, as a scientist and a person interested in bird conservation, that we are losing nightjars at a very rapid rate,” Ward says.
So the pair embarked on a more focused project five years ago to better understand whips. They deployed graduate students to different places in the state to band and collect samples from birds and the places where they still make their distinctive nighttime calls. This year, the researchers added four more states—Michigan, Ohio, Wisconsin, and Missouri—to their roster, and plan to do more work in Mexico.
Among their goals is to understand the moth species the whips like to eat, how they might be affected by the pesticides in the soil, and whether the habitats the birds like best filter those toxins. Recent research suggests that whips travel from their nests in forested areas to more open nearby expanses to forage for moths. Ward and Benson are testing whether those open areas within forests, especially those with sandy soils like at Sand Ridge, carry less of a pesticide load, allowing more moths to survive, particularly among the Midwest’s vast stretches of corn and soybean fields.
“The whip-poor-wills, we think, are giving us an opportunity because of their unique life history and where they occur, both in agricultural areas, but also in some pretty intact forest habitats,” Ward says.
If the ornithologists can identify hot spots where whips exist and the drivers of their success, conservationists could potentially protect those areas and replicate the conditions elsewhere by providing tailored recommendations for nightjars to forest managers and potentially farmers. The result, says Ward, could slow or even stop the population declines.
Setting a Baseline
As the sun sets, the whips begin to call. Witynski, wearing a baseball hat over his brown hair, and Moline set out insect traps, buckets with purple-UV LED lights affixed to the opening to lure insects. What the researchers find inside at the end of the evening will help them determine what species are most abundant in the area throughout the summer and, therefore, what is most available for the whips.
The pair also stakes poles for a mist net along a forest edge. Towhees and Wood Thrushes call in the waning light. At dusk, when the whip-poor-wills start calling, Witynski puts a playback device below the net, crouches behind a tree, and remotely starts the recording.
Whips are very territorial, calling to identify their boundaries, yet we don’t know how large those areas might be. Ornithologists do know that they’ll fly to where they hear another whip calling, flap their wings, and generally try to look tough to let them know the territory is taken.
Just as the purple dusk darkens to night, a whip flies into the net. Witynski swiftly switches his headlamp to red to protect the bird’s extremely sensitive eyes. When walking around in the dark, the researchers’ headlamps reveal the birds’ locations, their eyes shining like reflectors in the light.
Witynski works quickly to remove the whip from the net and get to work. He bands the bird, a male, weighs, and measures him. He blows aside the bird’s belly feathers to look for fat stores, a sign of health, and a cloud of sand wafts into the air. Witynski then puts him into a cardboard box and waits a few minutes, hoping the bird will poop. The researchers send the samples to a lab for fecal meta barcoding, where genetic material shows which species the birds eat. Witynski will then compare that information to the species he collects in the insect traps.
Moths are a critical part of the equation, says Benson, and one we need to know more about. Then people can ensure that certain areas exist that are suitable for them. In addition to his work in the field, he’s raising moths in the lab in different soil types and hopes to determine which pesticides they take up in their bodies.
Ornithologists hypothesize that one reason for the falling nightjar numbers is changing agriculture practices. Whips and other species once heavily relied on farm pests, which benefitted farmers and birds alike, a concept researchers in the 1800s called economic ornithology. But in the last 70 years or so, industrial agriculture has converted an ever-growing amount of land to row crops, eliminating pasture woodlands that may have provided ideal habitat for these species.
Add the widespread use of pesticides to those lands, potentially wiping out food sources for insectivores, and you get fewer birds on the landscape, both during migration and breeding seasons. To test the theory, Ward and Benson have gathered soil samples at two dozen locations in the region to check for pesticide residues and are awaiting results.
Authors of a paper published this year in PNAS supports the idea that industrial agriculture threatens birds by eradicating large swaths of the habitat and resources they need. In the study, researchers used radar data to analyze birds’ migration patterns. They suggested that the agriculture-dominated Midwest is now an “inland migration barrier for forest birds,” the authors wrote.
The seven-acre area Witynski studies has the highest density of whips in the state. The data from Sand Ridge, now collected for the fifth year running, could offer a baseline for whips and provide insight into what conditions the birds prefer. Of the eight whips caught so far in the season, three already had bands. One of Witynski goals this summer was to capture birds that researchers equipped with temperature loggers last year. The devices could offer Ward and Benson more long-term data points on the birds and how they survive the winter.
At the end of the evening, Witynski recovers the insect traps and investigates his quarry: common gray, tiger, and cutworm moths, some with black and white geometric patterns, others with pink and yellow markings. He puts them into plastic bags marked with the date and location to observe more closely later.
He watches the stars for a few minutes and packs up the truck around midnight, but not before explaining that although Sand Ridge is a whip-poor-will hotspot that could yield more about the bird’s natural history, there are even more whips further south.
Located near the southern tip of Illinois, Dixon Spring is hilly and largely forested, the perfect place to investigate which habitat types Eastern Whip-poor-wills and the larger Chuck-will’s-widows prefer. Whips might need a combination of habitats to do well, so there, and even further south in Missouri, Holly Coates, another University of Illinois ornithologist, is looking at the effect of land management on the nightjars and where they exist in the area.
A tall blonde woman with nearly a decade of technical experience, Coates, like Witynski, captures the birds in mist nets, bands and measures them, and collects fecal samples. But she does so at various managed forest areas that abut unmanaged areas. Many of those are rife with invasive plant species and a dense understory and canopy. What she finds may help determine which habitat types the whips like best. The places where she works include properties managed by the state and federal government, and private landowners.
In Missouri, Coates conducts research on land privately owned by the L-A-D Foundation, a group dedicated to the responsible management of the Pioneer Forest, to see if their practices might prove beneficial for whips. The organization selectively logs a small number of white pine trees to use for wine barrels. Coates’s research might help the foundation determine whether nightjars do well in areas where they practice that type of forest management, one that creates an open canopy and space that allows the birds to better see and hunt moths.
The Illinois Department of Natural Resources, which manages land for wildlife, is paying close attention to the research on the private land. Coates’s ongoing work could also influence their practices. “It'll be great to learn if what we're doing is attracting these birds,” says Kevin Sierzega, a heritage biologist with the department. He helps manage properties to protect wildlife in the state, including species of nightjars. “We know they're in the area, but we don't have enough information to say how much they're utilizing it.”
“Most people don’t know what they have, they just look out and see green.”
Sierzega enrolls private landowners like Dan and Georgia Spivey in a program that provides financial incentives when they reduce the canopy, keep invasives at bay, or allow controlled burns, which could prove useful for whips. The couple owns more than 100 acres in the area, including a 40-acre limestone glade in the program. Dan has heard Eastern Whip-poor-wills and Chuck-will’s-widows, the latter listed as a threatened species in Illinois, ever since he bought the property four decades ago. Reducing the canopy, “improves the habitat for moths and butterflies and birds,” he says. “Most people don’t know what they have, they just look out and see green.”
Coates hopes to find which of those verdant areas the whips use with help from large antennae set up just weeks prior at a few of her research sites. When she captures Eastern Whip-poor-wills, she will strap on a tiny backpack that records their locations, allowing her to see where—the managed or unmanaged—they fly to and from.
“It's not necessarily that one management type is going to be better than the other,” she says. “We're looking at the structural characteristics formed by these styles,” like whether the whips are more abundant strictly where forest canopy is thinner or whether they like a combination of forested and open areas.
On a late spring night, she carefully climbs over and around felled trees, bending branches as she sets out insect traps. She marks their location with a pin on her phone and unfurls a mist net. The forested terrain is more difficult to navigate than at Sand Ridge, and the soil not nearly as sandy, but at dusk, the whips begin their calls. Barred Owls meet in the tree branches overhead and loudly greet each other. Coates plays the recording—the same one broadcast by Witynski—and sits on a log to wait.
We still don't really know much about these birds, she says: “It’s very cool to be in on this at the starting point.”
After a while, her headlamp reflects two disks of light: a whip in the net. She collects her measurements and straps the backpack onto the bird, securing the knot with a dab of super glue. Finally, she releases the bird, the first of her backpacked whips to fly into the night, one that will tell her where it spends its time and how we can help it survive.