An Aural April

On a misty morning in early April, I set out on a listening walk. The fog was so thick I could barely make out the trail in front of me. But although my visibility was almost zero, my hearing was excellent.

First I stood in our yard and listened to the assorted whistles of a flock of red-winged blackbirds that filled up several of our black walnut trees. These birds always visit us during foggy days in early spring.

I also heard the cheerful singing of Carolina wrens, the “cheer, cheer, cheerily” of American robins, the “wick-a-wick-a” call of a northern flicker, and the excitable “churring” of a red-bellied woodpecker. Song sparrows held forth from the weed tops of First Field and American goldfinches gave their “per-chik-o-ree” flight calls as they navigated overhead.

Down along our road I glimpsed a pair of Louisiana waterthrushes through the fog. One scolded on a branch above the stream; the other silently walked on a branch in the stream. Two days earlier I had heard their ringing, cascading song that out-competes rushing stream water as I walked up our road, but on this day they seemed to be silenced by the fog.

Not so the first returning blue-headed (formerly solitary) vireo. His louder, more definitive rendition of the red-eyed vireo’s song is also higher in pitch, and that morning it rang from the woods above the stream.

Sitting on the Hunters’ Bench beneath huge Norway spruces that dripped with condensed fog, I listened to the syncopated drumming of a pileated woodpecker, the musical, rising “chur-lee” of an eastern bluebird, and the buzzy trilling song of a chipping sparrow.

I walked up the Steiner/Scott Trail and was stopped in my tracks by a ruffed grouse drumming so close by that I could hear its reverberations, yet I could not locate him or his drumming log even though I sat and listened and peered through the fog at all the likely places. Instead, I was rewarded by the first singing ruby-crowned kinglet of the year. His song, a complex series of notes and warbles, always ends with “look-at-me, look-at-me, look-at-me,” only I couldn’t see him either.

Next I heard the cat-like mew of a yellow-bellied sapsucker and spotted him through the fog, sipping sap from a hickory tree that was encircled by old sap wells and overhung with grapevines.

A deer loomed like a specter ahead in the fog as I reached the Sapsucker Ridge Trail, but it looked at my silhouette and fled. Squirrels scolded unseen. At the Far Field a field sparrow sang his plaintive, minor key song the entire time I circled the field on Pennyroyal Trail.

Then a turkey gobbled below me. I sat and listened as he gobbled on and on, but again I could see nothing. A northern cardinal sang its brilliant “clear, clear, pretty, pretty, pretty” song; an eastern towhee called “che-wink,” and a white-breasted nuthatch “yanked” from a nearby tree trunk. Still, the turkey gobbled, stopping only when I continued my walk. I may not have seen him, but he must have seen me.

By the time I reached the Far Field Road, visibility had widened only to 100 feet in all directions. Below the road another unseen grouse drummed. Along First Field Trail I heard the liquid, quiet, burbling song of a brown-headed cowbird.

When I finally walked back into our yard, three hours after I had left it, towhees, cardinals, field sparrows, Carolina wrens, red-winged blackbirds, chipping sparrows, goldfinches and song sparrows called and sang in the still thick fog. After an almost silent winter, I welcomed the swelling chorus of songbirds, both residents and migrants.

In April, if I am lucky, I hear the songs of some of our wintering birds before they move on to their breeding grounds–the lilting warbles of American tree sparrows, the haunting “Oh Canada, sweet Canada, Canada, Canada” of white-throated sparrows, and the musical trills of dark-eyed juncos. I am also delighted to hear what I think of as the inverted eastern meadowlark song of brown creepers and the tinkling, trilling song of winter wrens that goes on as long as ten seconds, making it the longest song of any bird in eastern North America.

Our year-round residents also tune their pipes, which, except for the Carolina wrens, have been relegated to calls for many months. “Tut-tutting” robins metamorphize into brilliant choristers; the “dee-dee-dees” of black-capped chickadees change to musical “fee-bees.” Tufted titmice “peter-peter” and mourning doves coo.

Best of all, are the returning birds, and I tick them off day after day by their songs–the thin, squeaky “zee-zees” of blue-gray gnatcatchers, the “wee-za, wee-za, wee-zas” of black-and-white warblers, the “witchedy, witchedy, witchedys” of common yellowthroats, and the “robin-with-a-cold-in-his-throat” of scarlet tanagers.

Then there are the brown thrashers, the most versatile of all American songbirds. Last April a male returned on April 16 and by the twenty-first he was courting a female in the guesthouse backyard. We sat outside after dinner and listened to unending thrasher diversity, each song repeated twice, a distinct pause, and then on to a new one. They only occasionally mimic other species and, unlike northern mockingbirds, their imitations are not very good.

So far, researchers have documented between 1000 and 2000 songs, depending on which researchers you listen to. Not only that, but brown thrashers actually sing two songs simultaneously even though they emerge from their throats as a single song, according to Barry Kent MacKay in his informative book Bird Songs.

Every year brown thrashers learn more songs despite singing only during a brief period each spring while they establish territories and attract mates. Most males hold forth exuberantly from exposed perches, their tails pointing down, making it easy to see as well as hear them.

Even on clear days, most birds are not as cooperative as thrashers so I continue to use my ears as much as my eyes. On one cold, windy morning I listened to juncos as I sat on Bird Count Trail. Suddenly, I heard a hissing sound. Through an understory of blackberry canes I spotted a displaying ruffed grouse, his tail fanned out as he shook his black ruff and then rushed at a robin on the ground nearby. When the grouse saw me, he flew off, but I remained sitting in the warm, sheltered spot.

Then I heard, as well as saw, tussling in the Japanese barberry shrubs to my left. Two male towhees emerged almost at my feet. The one in the lead picked up a twig, carried it a few feet, dropped it, hopped a few feet further, and flew. The second towhee flew back near the barberry shrubs. Both continued calling, but the one nearby sang a few bars of “drink your tea.” Later, I learned that I had witnessed “debris-carrying” which is performed by a relatively subordinate bird during territorial boundary disputes.

The climax to my aural April occurred on the twenty-fourth when our son Dave interrupted my breakfast at 7:00 a.m.

“Mom, come quick! A hermit thrush is singing on Laurel Ridge.”

Although I see hermit thrushes during both the spring and fall migrations, they rarely sing, and when they do, their songs are brief. So I didn’t have much hope as I dropped everything, pulled on my hiking boots and, with my apron still tied around my waist, ran up Guesthouse Trail behind Dave.

But three-quarters of the way up the ridge, the hermit thrush was still singing. He was so close that we heard every nuance of his ethereal song. Then, a particularly strident blue-headed vireo began to sing, silencing the hermit thrush. I waited for a short time and heard nothing more.

Finally, I continued to the top of the ridge and turned right on Laurel Ridge Trail. After a couple hundred feet, I heard the hermit thrush singing again and sat down as reverently as if I were in a church to listen to his organ-like tones. For a short time, he sang a solo. Then the first ovenbird of the year piped up with his far inferior “tea-cher, tea-cher, tea-cher” song and two blue-headed vireos, one on either side of the hermit thrush, joined in.

This time he was not deterred by his competition. The hermit thrush was clearly the master and the other birds mere apprentices and they quickly subsided.

I listened raptly as he sang, but slowly the volume of his song lessened as he moved further along the ridgetop. After half an hour, the concert was over. I never saw him fly. I never even caught a glimpse of him. He remained an enchanting, disembodied voice in the spring forest.

The late Sigurd Olson, in his book The Listening Point wrote, “Everyone has a listening point somewhere…some place of quiet where the universe can be contemplated with awe…” His listening point was on the remote shore of a North Woods’ lake in Minnesota. Mine is on a mountain in Pennsylvania’s ridge-and-valley province, especially in spring when hearing birds, like hermit thrushes and our resident wood thrushes, is even better than seeing them.

Minstrel of the Woods

I don’t have to leave this planet to hear the music of the spheres. Surely, listening to wood thrushes singing is as ethereal an experience as any mortal can hope for on earth. Many evenings, when I step outside, wood thrush song envelops me and it seems as if all the world’s wood thrushes are singing on our mountain.

Most years I can count on the first wood thrush song between April 30 and May 5 and the absolute last wood thrush song near the end of July. But, in 1997, I heard a wood thrush singing on August 5. The following summer a wood thrush broke that record by singing for a few brief moments at dawn on August 12. Then, last summer, the final date was August 3.

No matter when it happens, though, I listen with an impending sense of loss throughout July. Once again, time is running out, and I have not yet had my fill of wood thrush music. They are with us too short a time, singing like what I imagine angels would sound like, then leaving me bereft the rest of the year. Yet, I wonder if I would be as enchanted by wood thrush song if I heard it all year long or if familiarity would breed, if not contempt, inattention?

Of course, what is exquisite music to me is serious business for wood thrushes. As soon as the males return from their fall and winter homes in the lowland tropical forests from southern Mexico to Panama, they sing loudly from elevated, exposed perches, intent on attracting females and defending their one-quarter to two-acre territories from other males.

Song duels between males, called “countersinging” by ornithologists, in which two males come to within ten yards of each other and alternate songs, are common during territorial disputes. When females arrive, males chase them and sing aggressively. Each male tries to attract a female to settle in his territory. Once he does so, the male sings in lower, hidden sites.

But there are singers and then there are the outstanding virtuosos. The flutelike ee-oh-lay is learned from adult wood thrush males during the fledgling stage. But both his mostly inaudible, short note introduction and trill-like ending are either innate or invented. Each part of his song has several variations and every male has his own repertoire. For instance, one Ohio male sang 18 patterns out of 90 possible ones based on his variations, according to a study conducted by D.J. Borror and C.R. Reese entitled “Vocal gymnastics in Wood Thrush Songs” back in the early 1950s. Another study of 115 wood thrush songs by Aretas Saunders showed ranges as wide as two octaves with the average thrush’s range slightly over an octave.

I well remember the organlike tones of a particularly varied wood thrush song I listened to one evening in a darkening wood. To my ears, the singer seemed to be singing for the pure joy of it. Whether birds have a musical sense is still debatable among scientists, but there is no doubt that they use musical devices, such as crescendo and diminuendo, as well as complex musical phrases, and that they continue to develop their songs long after they have mated and established a territory. In fact, after a lull in their singing in early June, when they are busy feeding nestlings, wood thrushes begin singing again in July with almost as much intensity as in May, and I often hear them countersinging.

One July evening, along the Short Circuit Trail, I counted three wood thrushes singing at the same time, each song coming from a different direction. On other summer evenings my walks take me from one singing wood thrush to another as I move in and out of a succession of thrush territories. Long after I return home, my ears ring with their tremulous echoes and vibratos and, like Henry David Thoreau, the wood thrush’s song “touches a depth in me which no other bird’s song does…it lifts and exhilarates me.” The wood thrush, he writes, is the “minstrel of the woods,” the “master of a finer-toned instrument…a Shakespeare among birds…”

Also known as “bellbird,” “song thrush,” and “swamp angel,” the wood thrush’s genus name Hylocichla is Greek for “wood thrush” while its species name mustelina means “weasel-like” in Latin, referring to its tawny head, wings and back which are supposed to resemble the color of a weasel. Otherwise, the wood thrush has a white breast and belly, liberally sprinkled with larger round or oval black spots.

The nicknames, “swamp robin” and “wood robin,” refer to its membership in the Thrush family along with other outstanding singers such as the American robin. Like robins, wood thrushes forage on the ground by hopping and then pausing to search. They also toss leaves aside and probe the earth with their bills. Once a male attracts a female, they engage in sexual chasing in which the female leads the way during silent, circular flights, interspersed by perching together. Copulation occurs on branches and most pairs are monogamous through the nesting season, which includes the raising of two broods. A small percentage nest with the same mate a second season. One female was unusually loyal, mating with the same male five years in a row and then with another male for three years.

The female chooses the nest site with some input from the male who indicates his preference by “pit-pit” calls and by bringing nesting material to the spot even though the female does the nest-building. It takes three to six days to fashion the cup-shaped nest anchored in a hidden tree crotch or shrub or on a branch five to 20 feet from the ground. Resembling a robin’s nest in shape, it is distinguished by a lining of rootlets and often has a piece of paper or white cloth hanging from the base. The ones I have found here incorporate a piece of plastic from the old farm dump instead of the cloth or paper. During the 1970s, when we had a large population of wood thrushes, I once found three nests within a couple hundred feet constructed in mountain laurel shrubs.

The female usually lays three to four, blue-green eggs, and incubates them from 12 to 13 days while the male perches on trees 20 to 30 yards from the nest and feeds, sings, or preens. He also guards the nest by standing on or next to the nest rim and sometimes singing while the female forages. He occasionally brings her food and freezes if an intruder approaches the nest.

Once the eggs hatch, the male does two-thirds of the feeding of nestlings until they fledge at 12 to 15 days of age. Then the parents divide up the brood and continue feeding them until they become independent and leave their parents’ territory at the age of 21 to 31 days. By then the female has begun laying her second clutch of eggs.

Since the 1970s, wood thrush numbers have fallen, both on their breeding and wintering grounds. Researchers in the Midwest pointed to excessive parasitism by brown-headed cowbirds, which lay their eggs in other birds’ nests for them to raise. The cowbirds grow faster and are more aggressive than the nest-builder’s young so usually the host species raises less of its own offspring. But in Pennsylvania, Jeffrey Hoover and Margaret Brittingham found that despite a nine-percent cowbird parasitism rate on wood thrush nests, there were no nest failures.

On the other hand, in a study done at Hawk Mountain Sanctuary by Hoover, Brittingham and Laurie Goodrich in 1990, fragmented forest habitat was the more critical issue. Wood thrush nests in small forest patches were more heavily preyed upon than those in larger forests.

Researchers have found that the primary predators on wood thrush eggs, nestlings, and/or fledglings are blue jays, common grackles, American crows, gray and southern flying squirrels, chipmunks, least weasels, white-footed mice, black rat snakes, sharp-shinned hawks, raccoons and pet and feral cats. But large, mature forests with well-developed understories provide better protection from predators.

Such forests are also an excellent source of the beetles, ants, caterpillars, moths, flies, bugs, spiders, sow bugs, snails, and earthworms that wood thrushes eat in the summer and feed their young. Later, after the fledglings have dispersed, and during migration, wood thrushes switch to fruits. Then they prefer more open areas that support fruit-bearing shrubs, vines and trees such as spicebush, fox grapes, blueberry, blackberry, mulberry, holly, elderberry, Virginia creeper, pokeweed, dogwood, black cherry and black gum trees.

Here in Pennsylvania the United States Fish and Wildlife Service’s annual Breeding Bird Survey recorded its highest number of wood thrushes per route in 1977 (22). Since then there has been a slow downward trend, but during the Pennsylvania breeding bird atlasing project–from 1983 to 1990–atlas volunteers found wood thrushes throughout the state in every county. Pennsylvania also holds the record for the longest-lived wood thrush–eight years and ten months old.

As long as suitable woodland habitat remains for wood thrushes here, along their migration route, and on their wintering grounds, wood thrushes will survive. As Thoreau wrote on July 5, 1952, “The thrush alone declares the immortal wealth and vigor that is in the forest…Whenever a man hears it, he is young, and Nature is in her Spring.”