Winter Visitor

Near the end of January I swept our back porch clean of an inch of snow before spreading bird seed. Immediately a sparrow throng of dark-eyed juncos, white-throated, song, and American tree sparrows mobbed the porch.

But one sparrow looked different from the rest and fed off by itself. Still, with its rusty-red cap it most resembled the four American tree sparrows, but it lacked a tree sparrow’s dot on its breast, gray eyebrow line and gray throat and neck. Instead, the mystery bird had a whitish eyebrow line and white throat and I thought it was a male chipping sparrow.

American tree sparrows are nicknamed “winter chippies,” because of their resemblance to chipping sparrows, but the tree sparrows at our feeding area continually chased off the chipping sparrow, since that is what it seemed to be. They seemed to have no problem figuring out that their almost look-alike was not part of their tribe.

I, on the other hand, wanted to make certain of my identification and insisted that my husband Bruce take a photograph of the chipping sparrow to send to our birding son Mark. He, in turn, posted it to the Pennsylvania eBird list, and everyone agreed that it was a male chipping sparrow.

I was pleased that he appeared on a Project FeederWatch day because I had never recorded a wintering chipping sparrow on our central Pennsylvania mountaintop, although they are regular breeders here in spring and summer. According to The Birds of Pennsylvania by Gerald M. McWilliams and Daniel W. Brauning, chipping sparrows are irregular winter visitors or residents where there is suitable cover near bird-feeding stations, but they are “usually found only during mild winters with little snow cover.” In addition, it is rare to find any chipping sparrows here beyond the third or fourth week in January.

But it had been bitterly cold and windy throughout January and the temperature as low as two degrees Fahrenheit below zero. We also had had frequent snow cover. Nonetheless, the chipping sparrow had evidently found shelter in the tall remnants of dried grasses and wildflowers below our porch steps at least for that day. Whether he found enough shelter and sustenance in our 37-acre meadow throughout the mild February or in the farm valley below, I didn’t see another chipping sparrow here until their usual spring appearance in early May.

The chipping sparrow—Spizella passerina—which is Latin for “sparrow-like finch,” was more aptly named by the “Father of American Ornithology” Alexander Wilson in 1810—Fringilla socialis—meaning “social sparrow” because even then chipping sparrows lived near human habitation. Then it was most likely rural homes, farmyards, pastures or orchards. Today chipping sparrows are also found in the suburban residential landscape of parks, gardens, golf courses, open woodlands, and woodland edges along roads and utility lines.

The fourth most widespread breeding bird species in Pennsylvania, the chipping sparrow is only behind the song sparrow, American crow, and American robin in abundance. Even during the days of John James Audubon back in 1841 he wrote about the chipping sparrow that “few birds are more common throughout the United States than this gentle and harmless little bunting.”

Breeding across Canada to Alaska and throughout most of the United States, chipping sparrow migrants return to Pennsylvania from Central America, Mexico and the Gulf coast of the United States as early as the second week in March although the peak migration here is the last week in April or first week in May. I usually hear the male’s dry, monotone trill before I see him because he maintains his acre of territory mainly through song, but he also uses threat displays, chases, and even fights.

Once he establishes his territory, he courts a female by singing and short chases and they pair up a day or two after she arrives, usually about two weeks after the male does. She solicits copulation by crouching, her head and tail raised and vibrating. They mate several times in succession either on the ground or in elevated places such as fences, tree branches, and telephone lines.

Here on our farm the electric wires are favorite places, and we tend to think of chipping sparrows as exhibitionists. Both sexes engage in what ornithologists call “extra-pair copulations,” and once females are on their nests, scientists have found that some color-banded males copulate with other females on neighboring territories.

During nest-building and egg-laying by a female, though, the male keeps close as if he is guarding her. She seems to choose the final nesting site in a wide variety of trees and shrubs, but conifers are preferred over deciduous trees. However, crabapple trees are favored next, followed by honeysuckle, various maples, ornamental trees and shrubs, hawthorn, currant and even vines such as English ivy. Wherever she builds her nest, usually it is hidden in foliage three to 30 feet from the ground.

Like most bird species, though, some chipping sparrows don’t follow the nest-building program. For instance, back in 1911, R.F. Miller reported that a chipping sparrow, three years in a row, nested in pepper plants hung up to dry in late summer in a shed on a Philadelphia County farm. Another nest, in Huntingdon County in 1923, was built in the bottom of a hairy woodpecker roosting cavity 10 feet from the ground. And Maurice Broun, the first caretaker at Hawk Mountain Sanctuary, wrote about a chipping sparrow nest 30 feet up in a maple tree overgrown with grapevines and another 50 feet on top of an oak tree.

The cup nest itself is built in four days by the female and is so flimsy you can often see through the rootlets and dried grasses she weaves and then lines with the hair of deer, raccoons, cattle, and humans, and has even been known to yank out hair from horses, her preferred nest-lining material.

She then lays two to seven pale blue to white, lightly streaked or spotted eggs and incubates them for 10 to 15 days. The male feeds her frequently while she is on the nest because she rarely leaves it especially near the end of the incubation period.

The nestlings emerge over a 24-hour period, and the parents immediately eat the eggshells. The male begins feeding their young within an hour of hatching while the female continues to brood her naked nestlings until they develop feathers. She gradually decreases brooding after their fourth day and joins the male in feeding them mostly weed seeds, followed by insects as the nestlings mature.

Eggs and nestlings are preyed upon by black rat, eastern milk, and eastern garter snakes, American crows, blue jays, and domestic cats while adults and flying youngsters are victims of Cooper’s hawks, American kestrels, red squirrels, and domestic cats.

Their nests are sometimes parasitized by brown-headed cowbirds, but often chipping sparrows alarm-call and use threatening displays to deter them and frequently desert nests with cowbird eggs in them. If a cowbird does hatch with chipping sparrow nestlings, both appear to survive.

After a nestling period of nine to 12 days, the young climb to the rim of the nest and then into tree branches and practice short flights. Their parents continue to care for them for three weeks or so, but the male does most of the care if the female is starting a second brood. Then the young gather in flocks of five to 15 birds to forage in weedy places.

Once their last brood is on their own, the adults leave their territory, and parents and offspring join foraging flocks of their own species as well as song and field sparrows, feeding in weedy fields, along fence rows and forest edges. Fall flocks range from 25 to as many as 1000 birds as they move in stages south for the winter along the coast and mountaintops, leaving Pennsylvania as early as mid-September and as late as the third week or later in October depending on the weather.

Because chipping sparrows occupy a wide variety of habitats during breeding and on their wintering grounds, they remain incredibly common birds with an estimated three million breeding males in Pennsylvania alone. So it looks as if we can look forward every spring to the return of these human-adapted birds.