Atlasing at night is the best way to document many hard-to-detect species, including owls, nightjars, woodcock, and rails. It also offers its own challenges, but with a little preparation and some luck, those challenges are accompanied by rewarding experiences.
The most important consideration when out at night is personal safety. Low visibility is inherently more dangerous, but these risks can be minimized. While the Handbook provides a good overview of general safety tips, some of the most pertinent considerations include parking well off the road along a visible section (not around curves or over hills), using your vehicle’s hazard lights when stopped, and wearing high-visibility clothing. You should also travel with a partner when possible and let someone know your travel plans. Never prioritize data collection over your safety.
Nocturnal atlasing is often focused on particular target species, and you will have more success if you plan ahead with your target species in mind. The season will determine which species are vocalizing, and ideally each block should have at least two nocturnal trips during two different seasons. One trip should be in early spring, when owls and woodcocks are most detectable, and one should be in early summer, when nightjars and rails are more easily found.
Great Horned and Barred Owls are the earliest species, and they are both actively calling right now. Listen for their duets, which you can record as code C (courtship display). Otherwise, their vocalizations should be coded as S (singing). By March and April, you should be listening for Eastern Screech-Owls and American Woodcock—the woodcock’s display should also be recorded as code C. May and June are when you can find nightjars and rails. Their vocalizations should receive code S, but they are good candidates for code M (multiple singing birds). For code M, listen for seven or more individuals calling in the same block on the same night. If their density isn’t high enough for code M, upgrade them a week later to code S7 (singing for 7+ days). The nighthawk’s buzzy peent call is not a good indicator of breeding, but their “boom” display can be safely recorded as code C. Finally, fledgling Great Horned and Barred Owls have distinctive calls that can be heard in early to mid-summer, providing a Confirmed FL code (recently fledged young).
Passive listening is an effective way to detect nocturnal species, but many of them respond well to playback (the use of a recorded vocalization to elicit a response from a bird). Although we discourage the use of playback for general atlasing—the impact of playback isn’t well understood, but it likely has deleterious effects on the responding bird—playback can be used judiciously to detect nocturnal species, especially owls and rails. Besides increasing the rate of detection, an advantage of using playback is that the responding bird can be coded as T (territorial).
Prior to atlasing, carefully planning out which blocks you want to visit and where in the block you want to go can be exceedingly useful. Concentrate on covering a block thoroughly before moving to a different block. Think about which species you want to target, then use satellite imagery or daytime scouting trips to find suitable habitat for that species. An effective technique is to drive quiet roads in a block, stopping at intervals of a mile or so and listening for 5–10 minutes. When planning your route, think about where you might want to stop; find spots near suitable habitat with a good shoulder or pullout (Google Street View can help with this), and avoid stopping in front of houses or around curves or hills.
Unfortunately, you can’t pre-emptively create locations in eBird. An alternative is to use Google Earth or Google My Maps to place pins at each potential stop; these can then be exported to your mobile device. You can find a tutorial for this here. When naming the points, it’s helpful to include the block name and the target species you are looking for. Once you arrive at the identified location, begin your eBird checklist. If you are alternating driving and listening, it’s best to do a series of Stationary checklists rather than one longer Traveling checklist.
It’s not infrequent that you don’t detect any birds at your stop; these zero-species checklists should always be submitted. However, you should be aware that these zero-species checklists will not show up on eBird block summaries or visualizations. It will seem like there is an error–and this does makes harder for you to track nocturnal effort—but those zero-species checklists are still registered in the Atlas database and are included in all analyses of Atlas data.
eBird identifies nocturnal checklists when they are started 20 minutes after sunset or 40 minutes before sunrise. This means that for your checklist to be included in nocturnal effort totals, it needs to be started 20 minutes after sunset or 40 minutes before sunrise (this is another reason why more, shorter checklists can be better than fewer, longer checklists).
Another important consideration before heading out is the weather. Calm nights with no rain will be most productive. If the wind goes above 10 mph, it can be hard to hear birds. Whip-poor-wills and Chuck-will’s-widows also vocalize more on moonlit nights; the best time to detect these two species is on clear nights within a week of the full moon.
Although “nocturnal effort” conjures images of haggard observers fueled by caffeine and moonlight, many species are actually just as detectable at dusk or dawn as they are at midnight—sometimes even more so. This means starting before dusk and atlasing for an hour or two will still get you back home at a reasonable hour. Similarly, you can begin a couple hours before sunrise. Particularly in late spring or early summer, this has the additional benefit of transitioning right into the dawn chorus—one of the most magical and productive times of day for an atlaser.