Caterwaul, Winnow, and Croak: Getting to Know Maine's Other Nighttime Songsters

An American Woodcock - one of Maine's most unusual "shorebirds", D. Ellis.

Given that this project is titled the Maine Nightjar Monitoring Project, it would be reasonable for you to conclude that all our efforts are focused exclusively on nighthawks and whip-poor-wills. While those species are our primary study targets, our volunteers and technicians detect far more than just nightjars while out surveying the Maine nightscape. Although most birds are diurnal – that is that they are active and sing during the day - twilight and night are surprisingly musical periods. Indeed, going out and surveying while most birds are asleep provides some unique advantages and an opportunity to listen for some rare and unusual vocalizations.

The Hermit Thrush - a regular singer during the waning daylight hours, L. Parker.

The hour leading up to and following sunset is an interesting time to seek out birds as it is a period of transition. It is during these twilight hours that a cast shift takes place. Many diurnal species use this period as a last chance to advertise themselves and their territories before sleeping through the night. Thrushes are particularly present at dusk. American Robin often belt out ceaseless streams of sweet music from utility lines and tree tops while Hermit Thrushes and Veery sing their ethereal songs from within the forest. Monitors near wetland areas may detect the thumping song of the American Bittern from within the cattails or hear the ticking calls of an otherwise hidden Virginia Rail. If you're really lucky, you might hear one of Maine's rarest and most secretive birds: the Yellow Rail. Volunteers in more developed areas may hear chips and chatters overhead and look up to see flocks of "flying cigars" darting to and fro. These little agile aerial insectivores are Chimney Swifts, a species that often takes up summer residence within abandoned buildings, barns, hollow trees, and chimneys. Monitors must know their "peents" when out surveying at dusk as there are two species that give "peent" calls: the Common Nighthawk and the American Woodcock. The nighthawks call is a raspy "peent" given while in the air and often interspersed with territorial "booms". The American Woodcock, by contrast, gives his more nasally "peent" calls from the ground in open areas near woodlands.

Monitors near wetlands may hear the thumping and pumping of the American Bittern who blends into emergent vegetation by pointing its bill upwards, L. Parker.

Surveying at the edges of the day also provides a chance to hear one of the most unusual "songs" in all of nature – the "winnow" of the Wilson's Snipe. The Wilson's Snipe is a fairly inconspicuous, long-billed shorebird that can be found along the margins of marshes and wet meadows. Although quite secretive and well camouflaged, this bird performs an attention-grabbing flight display. Taking flight from their place hidden among the vegetation, the snipe flies high into the air before making a rapid descent. While descending, the bird spreads its tail feathers. Air rushing through these feather produces a loud, tremulous, and haunting sound that carries long distances. It is a true spectacle to watch for the spiraling silhouette of this enigmatic shorebird against the reds and oranges of the setting sun while hearing its bizarre territorial, non-vocal song.

Barred Owl, L. Parker.

After the sun sets and the moon begins to rise, a new cast of characters emerges to sing their song unseen. These are the hours of the Eastern Whip-poor-will, whose singing peaks on clear nights after the moonrise. They are not the only nighttime songsters, however. Many owl species sing primarily after dark. Roughly 2 hours after sunset, the songs of one of Maine's smallest owl species can be heard. The song of the Northern Saw-whet Owl is a monotone series of "toots". Despite their small size, their songs carry great distances and are used to claim breeding territories. The classic "hoo"s of the Great Horned Owl can also be heard on moonlit nights in spring as males call from nearby their nests. Females may respond and together the pair will perform hooted duets. Like the Great Horned Owl, male Barred Owls will also call from near their nesting site. Their call is often described as sounding like "Who-cooks-for-you? Who cooks for you all?". Barred Owl pairs will also perform duets, although of a much more usual nature when compared with other owls. These duets are referred to as caterwauling and have been described as sounding like wild laughter composed of raucous cackles, gurgles, and hoots. By courting, bonding, and advertising their territories at night, owls are able to perform essential breeding season rituals without drawing drawing the ire of diurnal birds who would otherwise harass them during the day. Because many owl species are opportunistic predators of nestlings, young, and even adult birds, crows, ravens, hawks, falcons, and even songbirds will mob and give chase to any owl they encounter. Being active at night means these owls can coexist within the same habitats as their would-be pursuers, who are generally asleep while they are most active and vociferous.

The Ovenbird - a warbler active by day and by night, L. Parker.

While you may occasionally hear the song or call of a songbird after dark, there is one wood-warbler that makes regular appearances during our survey efforts. In fact, it is one of the most common birds reported by volunteers each year – the Ovenbird. This ground-nesting songbird is very familiar to daytime birders as it sings its loud refrain of "teacher! teacher! teacher!" from within our woodlands. The Ovenbird lives a double life, however. Although a consistent and regular songster hidden within the forest by day, this secretive warbler takes to the treetops by night to perform courtship display and sing a highly variable song. After emitted a few sharp chip notes, the male Ovenbird shoots up from the canopy and hovers above the trees with tail feathers spread while singing a rambling song consisting of "whinks", "bleeps", "chips", and maybe a "teacher!" or two. Sometimes, if you're lucky, you might spot the hovering songbird against the moon before he darts back into cover, often chased by another Ovenbird. Going out in search of this novel song is worth the effort in and of itself just to experience the other, showier side of the Ovenbird's personality.

Birds aren't the only nighttime singers! Listen for the droning bellows of the American Bullfrog and other amphibian choruses, L. Parker.

In addition to the birdlife heard at and after dusk, there are a wide array of other wildlife sounds that can be heard. Packs of howling and yipping Eastern Coyotes can often be heard off in the distance on calm summer nights. Humid nights or those following a rainstorm often lead to an increase in amphibian calling. American Bullfrogs, Gray Tree Frogs, Northern Leopard Frogs, American Toads, and many others contribute to nighttime chorus in wet areas near vernal pools, ponds, and marshlands. Among the peeps, trills, and snores of our frogs, you might hear the bark-like croaks of a Black-crowned Night-heron, one of Maine's more elusive wading bird species. Occasionally the startling cries of a vixen Red Fox may take you by surprise as you strain your ears for a distantly singing whip-poor-will – I can tell you from firsthand experience that it is quite the goosebump-inducing rush! Sometimes, you might find yourself standing on the roadside hearing nothing at all. It is during these times that I stop to appreciate the sparks of passing fireflies, watch for silently drifting luna moths, or bask in the silvery glow of full moon. Nightjar surveying is never boring.

The secretive Black-crowned Night-heron hidden within a thicket, L. Parker.

Interested in hearing these fascinating and illusory nighttime species for yourself? Consider adopting and monitoring one of our routes so that your observations can be used to inform the conservation of these birds. Each year, our volunteers experience and share a wealth of memorable wildlife experiences from time spent in the field. I'll be leading a webinar on nightjar monitoring on May 9th at 1 o'clock. You can RSVP for that here. Not able to take to part, but want to stay up to date while supporting the effort? Consider becoming a member of the Maine Natural History Observatory. Members have the benefit of staying up to part with this and other efforts around the state all while helping to sustain these important long-term monitoring projects from year to year. Whatever your situation, I hope you consider taking some time to get out and get to know Maine's natural night life, be it from the field or your back porch.