In the soft light of pre-dawn, dozens of ghostly robins fed busily amid the stubble of the soybean field. All around me the grackles and red-winged blackbirds filled the air with raucous calls, squawks and strident songs. Just ahead, smaller birds flitted through bare vines tangled in the low, brown scrub at the edge of the field. These nondescript birds ventured a few feet away from the safety of the hedgerow into the field where they scratched through the clay-colored sandy soil for seeds.
I lifted my binoculars and a host of little brown birds danced in and out of view. I took a step closer, the soft soil swallowing the sounds of my steps. A sentinel bird caught my movement, though, and alerted the group. In an instant, the little flock darted back into the cover of the thicket.
They were white-throated sparrows (Zonotrichia albicollis), one of our most abundant winter sparrows. Sparrows present an identification challenge for many bird watchers. They are sometimes unceremoniously called LBBs-little brown birds, or LBJs-little brown jobs. Minor differences in head stripes, wing bars, breast patterns and color can define a species. Many sparrows show significant variations even within a species, adding to the confusion. These sparrows have a diagnostic white throat patch that gives the species its name. Like many sparrows, the head is striped, and the back and wings a combination of browns and blacks. In adult white-throated sparrows, the beak, neck and cheek are gray. Youngsters have streaked breasts. The short, dark, conical bill is ideal for cracking open seeds.
I stood still, and the skittish birds returned to the field to feed. Something I hadn't noted momentarily startled them, and they retreated once more. They must have been using all of the calories they were consuming just to fuel their frenetic activity.
White-throats are large by sparrow standards-about 6 inches. They weigh about an ounce. Both sexes look alike, although males, on average, are slightly larger.
Fortunately, white-throated sparrows are somewhat easier to identify than most. Besides the tell-tale white throat patch, these sparrows have other distinctive markings. A yellow spot, surprisingly bright on many individuals, rests just in front of the eye. If I saw one of these birds in profile, this lemon teardrop would have been an even better field mark than the throat. Even more remarkable, though, is the variation in head stripes.
Two color morphs exist. In some birds, the head pattern shows a narrow, central crown white stripe, set off by a black stripe, then another, wider white one. A black line extends back from the eye to complete the pattern: white-black-white-black. The other morph substitutes tan for white in the head stripe pattern. This variation is genetic.
Long and close study of these common birds has yielded a fascinating example of gender preferences. In the avian version of "gentlemen prefer blondes," male white-throats prefer females that are white-striped. This preference is uniform, whether the male is white-striped or tan-striped. But females of both morphs prefer tan-striped males. Enough balance exists in mate selection that both morphs continue to be well-represented in the population.
It is late winter and the colors have faded a bit on this tiny flock. By the time they arrive in Canada and begin breeding, they will sport fresh feathers and their most distinctive coloration.
The birds I was watching were giving 'tseet' contact calls to one another, but none were singing. If one had sung, I would have heard a tune that starts with a clear, two-noted whistle, followed by a rapid pattern of three notes on a different pitch. In the United States, it is usually rendered, "Old Sam Peabody-Peabody-Peabody." In Canada, birders hear it as "Oh Sweet, Canada-Canada-Canada." In the endless daylight of midsummer on the Arctic breeding grounds, males may sing this patriotic tune all night long. Only males sing, as they define and defend their territory and attract mates.
White-throated sparrows breed primarily in Canada. There, they construct small cup nests of grass on the ground or low in the brush. These birds are largely monogamous, usually producing one brood annually in a short space of time. Both parents incubate the three to five eggs for two weeks. The chicks hatch, and 10 days later they fledge.
The sky continued to brighten, and the sun inched over the distant tree line. I turned back toward the farmhouse, in search of my own breakfast. At the same hour the next day, I put on a suit and tie, ready to return to work. There, I found the usual diversity of dress and voices. And once again, it was time to decode the signs that define who these people are. I longed for the relative simplicity of sparrows.