Finding nightjars

If only all bird songs were as user-friendly as those of nightjars!

They’re simple. They’re loud. They’re repeated so often that you couldn’t forget them if you tried. Best of all, nearly all North American nightjars are named after them. Imagine, an entire group of feathered onomatopoeias, doing everything in their power to identify themselves for you.

There is a catch, of course: Nightjars are some of the most cryptically patterned birds on the planet. Their dappled plumage blends seamlessly with their preferred habitat. Worse, they are prone to sitting motionless and silent for long periods of time. One species is even known to hibernate, tucked out of sight for the coldest part of the year.

And, oh yes, they’re nocturnal.

Characteristics such as these can make for frustrating birding: staring intently at open ground in the fading light, a loudly calling bird stubbornly refusing to materialize, your binoculars finding only dirt and plant litter. I am sure that we’ve all been there, trying in vain to turn a pile of pine needles into a Chuck-will’s-widow, or chasing a Common Poorwill’s call up one side of a hill and down another.

They also explain why most birders can do serviceable imitations of nightjars’ calls, but few can actually say what the birds look like. Asking people to describe a whip-poor-will can yield fascinating results. I’ve heard everything from loons to roadrunners depicted in their place. Many birdwatchers resign themselves to blank spots on their life lists, hoping for pure luck to guide them, and most are likely still waiting. After all, nightjars are perfectly evolved to make you doubt your eyes even if you do stumble onto one, so how could sighting the birds on a regular basis even be possible?

It’s simpler than you think.

As with any bird, the most important factor is understanding their nature. For this, I turned to two leading nightjar researchers: Mark Brigham, the head of the biology department at the University of Regina, Saskatchewan, and Michael Wilson, a senior biologist at the Center for Conservation Biology in Virginia. Guided by their knowledge, you could be a lot closer to coming face to camouflaged face with a nightjar than you realize.

Of the sun and the moon
North America hosts six species of regularly occurring nightjars: Buff-­collared Nightjar, Common Pauraque (pronounced “pa-RAW-kee”), Common Poorwill, Chuck-will’s-widow, and Eastern and Mexican Whip-poor-wills. (The single species formerly known as “Whip-poor-will” was split in two in July 2010.) All are nocturnal or crepuscular. By day, they can be nearly impossible to find, short of accidentally flushing them, since they remain motionless and well camouflaged while the sun shines. To locate them, you need to search when they are the most active, and to do that, you need to be mindful of the two things that most influence their activity levels: food concentration and available light.

Let’s start with food. Nightjars depend on their sharp night vision to help them detect and catch airborne prey, usually insects. The birds’ foraging windows are therefore strongly tied to insect activity levels. Ideal conditions are still, dry, warm evenings with minimal temperature differences between day and night.

Rain, wind, and drastic changes in weather and temperature all decrease insect activity. Nightjars aren’t likely to waste energy foraging when their prey has been grounded.

It makes sense, then, that nightjars, Neotropical migrants, move from the tropics into North America only after temperatures and insect numbers have become favorable. They are among the later migrants, generally arriving on their summer grounds from late May to mid-June, and they are some of the first birds to leave in late summer. A few areas in the extreme southern United States host nightjars year-round, but in most of their range, the best months to find them are May, June, and July.

The availability of prey is clearly important, but it is only half of the equation. Many nocturnal hunters depend on senses other than sight, but nightjars rely on their sensitive vision primarily and are heavily influenced by light intensity. In fact, you could say their lives revolve around moonlight. It drives the nightjars’ ability to forage perhaps more than any other factor, but it’s routinely overlooked by birders.

Nightjars’ beautifully adapted eyes are ideally suited for dim light but are much less effective in daylight or extremely low light. The birds aren’t likely to hunt on dark nights with a new moon for the same reason they won’t hunt in the middle of a sunny day: They wouldn’t be able to locate prey successfully, and they would expose themselves to predators that have the advantage in those conditions.

Conversely, twilight and moonlit nights put nightjars in their element. “Moonlight is likely the most important consideration for finding nightjars; there is more foraging, more calling, and a much better chance to detect them if the moon is at least half-full,” says Wilson. Full-moon nights provide a constant low level of light and are absolutely the best, allowing the birds to remain active from dusk to dawn.

Not many birds can afford to be this particular with their feeding behavior, but nightjars have found a way to cope with too little or too much light: They can induce torpor. That is, they can lower their metabolism to conserve energy while they wait for the right conditions. And the Common Poorwill can go a step further: It can slow its metabolism into actual hibernation, a unique ability among birds, and one that allows the species to winter farther north than our other nightjars.

From a birder’s perspective, this means it’s wise to save your efforts until conditions are best. The birds can certainly hold out for the next warm, moonlit night. To avoid wasting your time, you should, too.

Location and detection
Although each species prefers its own specific habitat, nightjar habitats share similarities. All birds, for example, prefer a mix of open areas and cover, rather than a more uniform landscape. The combination satisfies their daytime need for hidden roosting places and their nighttime need for open hunting areas. Depending on the species, a great spot could be a grassy clearing in pine woods, the edge where a hardwood forest meets farmland, or a rocky outcropping in scrubby grassland.

Nightjars hunt by sallying out and back from favorite perches or directly from the ground. Perfect habitat has patches of bare, exposed ground. Areas recovering from recent burning, pastures bordered by wood fence posts, or clear cuts that are only a few years old often fit the bill nicely, as they provide a good combination of bare ground and prominent perches. Scout areas that look likely during the daytime, making special note of posts, stumps, rock piles, bare scrapes, and exposed ground.

Locating a good site can be a lot easier if you have evidence that the birds will actually be there, so it pays to do your homework. Check breeding bird surveys. They often have detailed information about areas near you that have hosted nightjars in the past and, barring any dramatic change to the ecosystem, are likely to hold them now.

Another great way to find nightjar spots is to keep up with local birding listservs, blogs, and online newsletters. Seek out locations where people mention seeing or hearing the birds. Nightjars set up small, local territories on their breeding grounds and favor particular perches. If one has been reported recently, it will likely stay in the area for the rest of the season.

If you have absolutely no idea where to begin, drive slowly around dusk along lightly used gravel or dirt roads through potential habitat. Nightjars will often be sitting directly in the road, so keep a lookout in your headlights and take care to avoid hitting them by accident.

Once you’ve found a likely location, things finally get a bit easier. If you are at a site under appropriate conditions, you should be able to tell almost immediately if your target is in the area. “Nightjars call year-round, and their calls are the absolute best way to locate them,” stresses Brigham. “If you haven’t heard them in an area, move on.” While you may hear them at any time throughout their residence, the birds tend to call more reliably and frequently in the early part of the season.

Familiarize yourself with the calls before you head out, and keep in mind that some syllables can be tough to hear at distances. The call of the Chuck-will’s-widow is a good example. The first chuck syllable is nearly inaudible at long range, and the rest can easily blur into an apparent two-note call. Listen to recordings of your target species, and pay special attention to which notes are emphasized. This will give you a better idea of what you are likely to hear initially in the field, avoiding confusion.

Once you hear a nightjar calling, all that remains is to approach without losing track of the bird, a task that’s easier said than done. It can be easy to be mis­directed by a call, rather than homing in on the location of the actual bird. Approach in short-distance increments, pausing after each movement to listen and readjust your direction.

The closer you believe you are to the bird, the shorter your increments should be. This will keep you from overshooting the bird or being drawn far off course, and make it easier to make minor adjustments and pinpoint a nightjar.

A good flashlight is essential in these pursuits, for two reasons. The first, of course, is your own safety. Venomous snakes, scorpions, and other undesirable critters cherish the same warm climates and dim light that nightjars do, and you need to see where you are placing your feet. Terrain can be a challenge at night as well, and no nightjar is worth a sprained ankle in the middle of nowhere.

The second is that a flashlight will allow you to use the incredible eyesight of nightjars to your advantage. Light that strikes their eyes will bounce off a reflective layer of tissue near the retina called the tapetum lucidum, producing extremely bright, amber-colored eyeshine, a dead giveaway.

You will see the birds’ eyes long before you see the rest of the body, so start out by searching for points of light, not the bird itself. Hold your flashlight at eye-level. Reflected eyeshine bounces back to the source; you’re not likely to see anything if you hold your light at your hip.

Lastly, a few words are needed for the sake of the birds. Nightjars prefer not to be seen at all. Approaching unnecessarily close or using boating lights, high-power lamps, and other extremely bright lights to make the birds freeze in place can stress them. You’ll see them fine through binoculars used in combination with a moderate-power flashlight. Moreover, the distance you keep will ensure that the birds remain calm and relaxed, rather than flying away in a panic.

Keep in mind, too, that any nightjar you see may have a nest in the area, and that nests are even more cryptic than the adults. A bird standing its ground and acting agitated is communicating that you’re too close; should you encounter this, inspect the ground for a safe path, then leave.

The two absolute most important tools for success in your search for nightjars are perseverance and patience. With a good understanding of their nature, locating them can be fairly straightforward, and their enigmatic charm makes them well worth the effort — as long as you can wait for the next full moon.

 

Chris Duke is a nature writer based in Seattle who has worked as a wildlife biologist for the World Parrot Trust in Bolivia. He has written all five articles in our birdfinding series. He thanks Mark Brigham and Michael Wilson, whose knowledge and help were essential for this article.

Originally Published April 20, 2012