Click to Enlarge Like other nightjars, Chuck-will's-widows (top left) don't build nests. They lay their eggs (bottom left) on the ground among leaves. The chicks (bottom right) hatch in about 20 days. Click to Enlarge A whip-poor-will is easy to see when it sits lengthwise on a branch (right) but is nearly invisible on the forest floor (left).   Listen for the night calls of Nightjars Beverly J. Letchworth Mark Raithel illustrations Have you seen a nightjar? Have you seen a nightjar? It’s not a jar you collect fireflies in before you release them, and it’s not an empty jar you left outside on the porch at night. A nightjar is a bird—even though it doesn’t look much like a bird. Some people think a nightjar looks like a giant brown moth, especially when it’s resting on the ground or a tree limb. Nightjars have big eyes, big heads and mouth whiskers, all important adaptations for a night predator. These whiskers may help funnel food into their mouth, or they may be used to feel for insect prey. Their bills are short, but their large mouths gape as wide as the bird's head. This helps them catch insects while flying. They have large wings and tails. Their legs are short and their feet are weak so they look awkward when walking. They also perch differently than other birds. Instead of sitting crossways on a limb like most birds, they sit lengthwise. Most species of nightjar fit the "no-see-em" description because their mottled brown coloring matches their surroundings and camouflages them. Of the almost 80 species of nightjars worldwide, three species live in Missouri: the common nighthawk, chuck-will's-widow and whip-poor-will. One species of nightjar is easier to see than the others. The common nighthawk, a jay-size bird ranging over most of the United States and throughout Missouri, can be spotted in big cities, small towns or in the country. Despite its name, a nighthawk is not a hawk, and it's not completely nocturnal, which means active at night. You can often spot nighthawks soaring overhead during the day, especially in the early evening. Nighthawks normally prey upon beetles, moths, grasshoppers, flies and mosquitoes. In a single day a nighthawk may capture and eat 500 mosquitoes. Researchers counted 2,175 flying ants in one nighthawk's stomach. A male nighthawk puts on a grand display flight to attract females during breeding season. Circling and hovering high overhead, he calls repeatedly, then goes into a steep dive. At the bottom of its dive, a nighthawk's wings make a "booming" sound as air passes through its wing feathers. This certainly makes a female take notice. Nightjars don't build nests. They usually just lay their eggs on the ground or a stump. Sometimes they put them on gravel roofs. They may scrape out a shallow depression for their eggs, but that's the extent of their nest building. If danger threatens, nightjar parents will move their eggs. Some nightjars have reportedly carried away the eggs in their mouths. If the eggs have hatched, they will carry the chicks between their thighs to a safer spot. If you're not sure the birds you see in the sky are nighthawks, listen for their "peent" call and look for a white stripe on each wing. These white patches can be seen from quite a distance and help identify the birds. Other nightjars may not be as easy to see, but in summer they let you know they're around by their loud calls. Probably the best known is the whip-poor will. After resting in the woods all day, the whip-poor-will wakes at dusk and begins calling its name over and over again in the darkness, sometimes hundreds of times without a pause. One whip-poor-will was heard calling 1,099 times without a break. If you are trying to sleep, these calls can be almost as irritating as they are beautiful. Whip-poor-wills frequently sit on country roads. Their eyes glow red when hit by car lights or a flashlight beam. Many species of nightjars show this bright eye shine. It is produced when light bounces off a reflective surface inside the eye that causes more light to enter. Whip-poor-wills frequently allow people to get quite close--within a few feet--before they fly away. Night Flying Hunters Animals that hunt at night have evolved various ways to find and capture prey in the dark. Compare the adaptations of these nocturnal predators. Nighthawk Fly: Narrow wings for fast, darting flight Find: Large eyes to see insects at night Catch: Wide gaping mouth to capture insects from the air Great-horned Owl Fly: Wing feathers with soft edges for silent flight to stalk prey unheard Find: Special ears for locating prey by sound and large eyes in front to see at night Catch: Strong, sharp talons for catching and carrying mice, rabbits and other prey Big Brown Bat Fly: Powerful wings for strong flight and quick turns Find: Makes ultrasonic cries, then hears echoes with large dish-like ears--an insect-finding radar Catch: Soft, thin skin stretched over wings and tail to swat and trap insects The chuck-will's-widow is the biggest of our nightjars. It lives in open forests and clearings in the southern half of Missouri. It is pigeon-size and eats insects. It catches them in flight or by flying low along the edges of woods and clearings, grabbing insects off the ground or vegetation. Small birds, frogs and toads are fair game, too. The chuck-will's-widow simply swallows them whole. It calls over and over again in a four-part chant, just like its name. If you're too far away, you may not hear the first soft "chuck" but the other three notes are loudly whistled. Some nightjars were given their strange names from the sounds of their calls. They are also called goatsuckers because people once believed the birds drank milk from goats. Actually, the birds stay near goats and other livestock to feast on the many insects that always gather around the animals. Their loud calls used to frighten people, but now we know that nightjars are just birds that are active at night. It's become fun on summer evenings to look to the skies for nighthawks and to listen for the calls of the whip-poor will or chuck-wills-widow.