Finches and House Sparrows

In Pennsylvania, purple finches nest mainly in the northern tier and at higher elevations in southern regions of the state. In winter, individuals from farther north overspread the state. Purple finches inhabit conifer plantations (including Christmas tree farms), spruce bogs, hillside pastures, woods edges and mixed and open woods. They are associated with larger forest tracts, but are often found at edges and in openings. In winter, they eat weed, grass and conifer seeds and other tree seeds (elm, ash, sycamore and tulip tree); in early spring, they consume buds and flowers of trees and shrubs; they take some insects in late spring; and they feed on fruits in summer.

The male has a melodious warbling song usually given from high in a tree but sometimes given mid-air, called “sky- larking.” The female builds a nest at any height from 3 to 60 feet above the ground, on a horizontal branch, usually in a conifer; she weaves a compact open cup out of twigs, weeds, rootlets and strips of bark, and lines it with fine grasses or animal hair. The two to seven eggs are a pale greenish blue, dotted with black and brown. The female incubates them for around 13 days. Both parents feed the nestlings, mainly with seeds, and they fledge about two weeks after hatching. One to two broods may be raised per year. In winter, purple finches may join foraging flocks with American goldfinches, pine siskins and other species. At feeding stations, house finches and house sparrows dominate purple finches and often drive them away. Despite that, purple finches are more numerous than those species. Purple finches winter as far south as the Gulf states.

Females are sparrow-like, and males are similar to male purple finches, except that house finches show more streaking on the breast and flanks, are not quite as robust, and are a more bright or “strawberry” red. The red pigment in both species comes from beta-carotene found in many plants, particularly in red fruits; the red blush to the plumage varies with the pigments in the food that is consumed during molt. House finches inhabit urban, rural and suburban environments and have adapted to a wide range of human- associated habitats. In the east, they are often found near human dwellings where they readily visit feeding stations. They feed on seeds, flowers, buds, berries, small fruits and insects.

Pairs often form within flocks during winter. Males do not stake out territories but, instead, defend areas around their mates. House finches begin nesting as early as March and produce two or more broods per year, each with four or five young. Females nest in a variety of sites including conifers, ivy along walls, abandoned nests of other birds, above porch lamps and in hanging flower baskets. The population of this western species “exploded” until around the mid-1990s, when a highly contagious eye disease, Mycoplasmal conjunctivitis, caused a dramatic population decline in the East. The disease causes respiratory problems and swollen eyes in house finches. Infected finches often die as a result of starvation, predation or exposure. Some birds do not die and may transmit the disease to flocks in other areas. It is important to regularly clean feeding stations with soapy water to prevent the spread of this disease. Although numbers have declined from peak populations in the mid-1990s, the Second Atlas of Breeding Birds in Pennsylvania shows the house finch to be numerous in Pennsylvania.

In Pennsylvania, the pine siskin is a rare breeding bird in most years. It nests mainly in the northern tier in stands of hemlocks, pines, spruces and larches, and in ornamental conifers in backyards. These tame birds become much more visible when they flock to feeding stations in winter. As well as eating seeds, siskins consume the seeds of trees (alder, birch, spruce and others), weeds and grasses. They also eat buds, flower parts and some insects. They usually forage in flocks, even during the nesting season; in winter, they are often seen in the company of goldfinches. During some years, many siskins winter in the Keystone State in response to cone crop failures in northern forests, and in other years few show up.

American goldfinches nest across much of North America from southern Canada south into the southern states in the east and across the west except for the southwest. In Pennsylvania, goldfinches are found statewide, absent only in small areas within major cities and portions within large contiguous blocks of forest. They forage in a variety of habitats including brushy areas, roadsides, open woods, woods edges and suburbs.

American goldfinches inhabit Pennsylvania year-round. Some winter in Pennsylvania. Others move in from the south in April and May, returning to breed in areas where they hatched, although they remain in flocks and do not set up territories until late June or early July. Goldfinches primarily eat seeds. In the spring, they forage for seeds, insects and insect eggs. In summer, they turn mainly to the seeds of thistles, dandelions, ragweeds, sunflowers and grasses. They eat elm seeds, birch and alder catkins, flower buds and berries. They clamber around in weeds and shrubs, picking out seeds. In winter, flocks may seem to roll across a field, as birds in the rear leapfrog over other flock members on the group’s leading edge. This strategy gives each individual access to fresh foraging areas while requiring only short flights to get there.

Goldfinches start nesting later in the season than any other bird in the Northeast. Perhaps breeding occurs late so that young hatch when seeds mature on favored food plants, particularly thistles. Flocks break up as males claim territories, in loose colonies, up to a quarter acre in size. The male sings from a perch, voicing a clear canary-like song, and makes high, circling flights. The female builds a neat cup lined with thistle or cattail down, 4 to 14 feet up in a horizontal or upright fork of a small tree or shrub. Goldfinches often nest in thornapples, shrub willows and gray dogwood clumps. The nest is woven so tightly that it will hold water; flexible, it expands as the young increase in size. The female lays two to seven pale bluish eggs. She incubates the clutch, with the male bringing her food. The young hatch after 12 to 14 days, are fed mainly on seeds by their parents, and leave the nest after another 11 to 17 days. Some pairs raise a second brood, and fledglings have been found as late as September. Cowbirds sometimes parasitize the nests of goldfinches, but the young cowbirds often die because they don’t get enough protein from the regurgitated seeds that goldfinch parents feed to nestlings.

House sparrows live year-round throughout North America with the exception of northern Canada. Never far from humanity, they inhabit cities, suburbs, towns and farms. They eat primarily grains and seeds including weed and grass seeds, crop and waste grains and livestock feed. They also consume bird seed, food litter and garbage. In summer, they will eat insects and spiders (about 10 percent of the diet), fruit tree buds and flowers. They nest in protected places, including holes in trees and buildings, porch and barn rafters, behind shutters and awnings, in bluebird houses, and in thick growth of ivy on the sides of buildings. House Sparrows aggressively defend potential nest sites and often destroy the eggs and young of native cavity nesters. They regularly displace nesting bluebirds and tree swallows. House sparrows use their nests for shelter during most of the year, an advantage in spring when competition for nest sites begins. Both sexes work at lining the cavity with grass, weeds, feathers and trash. Pairs are monogamous; prolific breeders, they produce one to four broods of three to seven young each. Recently-fledged juveniles form flocks in summer and are joined by adults after the breeding season ends in August and September. In late fall, pairs return to their nest cavities.

When house sparrows overran the United States in the early 20th century—ousting native breeders, fouling buildings with their droppings, and offending people with their aggressive, noisy habits—those who had championed the species’ introduction were roundly castigated. The population peaked in the early 20th century. Since then, it has fallen. Several factors may be involved: tractors and automobiles have replaced horses, and farming operations have been sanitized, so that grain is no longer widely available in winter. Yet, dairy barns can host many house sparrows and still have large populations of this invasive species.