High above, perched on a bare branch, the slender silhouette stands out against the azure morning sky. With an upright posture and a long tail, the bird reminds me of the elongated elegance of a Modigliani sculpture. From my vantage below, three sets of large white spots are visible on the underside of the black tail. The bird drops off the branch with a smooth flight befitting its graceful figure and is quickly lost in the dense forest canopy.
If I have any doubt about the bird’s identification, it is erased a moment later. A hollow “ku-ku-ku” calls out its name. It’s a yellow-billed cuckoo (Coccyzus Americanus). The song is wooden and far different than the musical tones we hear coming out of old-fashioned cuckoo clocks. It is distinctive nevertheless and a great way to identify this somewhat secretive bird.
I’m with a group of birders on an early Monday morning in the National Arboretum, the U.S. Department of Agriculture’s research and education facility. It is an oasis of more than 400 acres for birds and birders alike in the District of Columbia. We are in an idyllic spot called Fern Valley. The trail wanders invitingly through native trees and understory shrubs and down alongside a small but lively stream called Hickey Run.
The yellow-billed cuckoo is a bit larger than a robin, with white underparts and a brown head and back. The primary wing feathers have a reddish blush. The body is slender and stretches naturally into a long, narrow tail. This cuckoo has a pale yellow eye-ring and a sturdy, slightly downward curved bill that gives it its name.
As we continue down the trail, the bird’s food source comes into view: tent caterpillars. Cuckoos, which almost exclusively eat insects, are one of the few species to eat hairy caterpillars. They can’t digest the caterpillars’ hair. It accumulates in the birds’ stomachs until they regurgitate matted pellets, much like owls do.
Yellow-billed cuckoos have an accelerated breeding schedule, perhaps the fastest of any avian species. They are one of the last neotropical migrants to arrive here each summer from South America to breed. The male and female jointly build a hasty, sloppy nest. The female will lay two to four eggs over a few days. The male will incubate them overnight, while the pair shares that duty during the day.
Less than two weeks later, the chicks start to hatch. In as few as five days the chicks fledge. The oldest may be ready to leave the nest when the youngest member of the brood is barely out of its shell. Within a couple of weeks, the new cuckoos are ready to start fending for themselves. But mom might already be laying eggs in a new nest, as yellow-billed cuckoos sometimes have two broods a year.
Unlike their notorious European cousins, yellow-billed cuckoos rarely engage in brood parasitism. That’s the term that describes the practice of laying eggs in somebody else’s nest and having them raise the young interlopers. Because the young develop so quickly, they can often hatch and out-compete their host species’ young.
Yellow-billed cuckoos have a summer range that extends from southern Maine west to Wyoming and down to our southern borders. Throughout the eastern two-thirds of the nation, these cuckoos can be found in open deciduous forests.
The species is still common, in part because of its extensive geographic reach. But its numbers are dropping fast. According to the U.S. Geological Survey’s Breeding Bird Survey, the yellow-billed cuckoo population has declined 45 percent since 1980. The birds need relatively large tracts to breed successfully, and the forest fragmentation that accompanies sprawl development appears to be reducing appropriate habitat.
Although they are far from rare, this cuckoo in the National Arboretum is the first I’ve ever identified in the field. As we continue our woodland walk, the distinctive call keeps grabbing my attention. It’s one I’ve heard before, but its identity had been lost in the symphony that fills the summer woods.
Obscured behind thick foliage, the cuckoo is invisible but not inaudible. Slowly I am learning to distinguish the individual instruments within this woodland orchestra. As I do so, I come to appreciate more fully the complex web of sounds that surrounds us in the woods.
When I sit down at my desk in less than an hour, I hope to do something similar: try to identify the unseen individuals whose distinctive voices can so easily be lost amid the cacophony of voice mail, meetings and other demands of modern life. But for another few minutes that task can wait. Right now, I have an orchestra to appreciate and a new instrument to learn.