Sunday, May 19, 2024

A female house finch finds a seed in North Cambridge in December 2021. (Photo: Richard George)

House finches (Carpodacus mexicanus) are native to arid regions of western North America, but they were once popular as singing caged birds because of their musical voice and the male’s rosy red hue. In the early 1900s, wholesalers in California captured house finches and shipped them to New York, where caged-bird dealers sold them as Hollywood finches. Keeping native birds is a violation of the Migratory Bird Treaty Act, though, so to escape being prosecuted, bird dealers released their finches around 1940.

A group of these birds became established on Long Island in 1941. Even though the birds were originally from a region with a warmer climate, these little birds did quite well for themselves in New York. They spread gradually to the Connecticut coast and from there traveled up the coast and the Connecticut River Valley to New England. The population in Massachusetts exploded by the end of the 1970s, especially in the urban areas of Pittsfield and Worcester. Today the finches are common in unforested land, especially in urban and suburban areas. It took only 50 years for the New York finches to spread so far westward across country that they were reunited with their native western cousins.

House finches especially like dandelion seeds, as evidenced by this finch in Avon Hill in May 2021. (Photo: Richard George)

In the mid-1990s, a pathogen from chickens transferred to house finches. Many eastern birds became infected with the eye disease conjunctivitis, which made their eyes red and swollen. Birds with conjunctivitis had difficulty seeing, making it difficult for them to find food or escape from predators. The house finch population quickly dropped by 50 percent. House finch conjunctivitis struck eastern house finches particularly hard. Since the eastern population arose from only a few New York birds, it has been speculated that lack of genetic diversity may have contributed to their vulnerability to this disease.

Two house finches survey the landscape in Huron Village. (Photo: Richard George)

House finches make cup-shaped nests of small twigs, grass and debris, often in evergreens, but also in ivy or potted plants, behind porch lights, in eaves or anyplace with a rooflike overhang 6 to 9 feet above the ground. The birds build their nests in Massachusetts any time from late March to July. The female constructs the nest and lays about four eggs from mid-April to August. The male feeds the female while she incubates the eggs. After about two weeks, the chicks hatch, and both parents regurgitate food for the youngsters. The birds fledge in a couple more weeks. The male continues feeding the fledglings. Dandelion seeds are a preferred food. Most other birds feed their young caterpillars, grubs or insects, but house finches feed their young mostly plant matter.

A male house finch in North Cambridge hops along a branch in October. (Photo: Richard George)

A house finch finds nest building material in May. (Photo: Richard George)

Adult house finches are largely vegetarian; seeds, buds, leaves and fruit make up 97 percent of their diet. In the spring, they consume dandelion and other weed seeds. They forage for grains, seeds and berries. They will sometimes eat small insects, such as aphids. They visit bird feeders, especially feeders that contain sunflower or nyjer (thistle) seeds.

Some house finches have two or more broods per season. Female house finches sometimes lay their second clutch of eggs before the first brood has fledged completely. This is possible because the male does most of the feeding of the chicks. After breeding ends, house finches gather in flocks in weedy fields or coastal dunes. By fall, some birds fly south, but many stay throughout the winter relying heavily on seeds in bird feeders. Females migrate farther south than males, which is why in winter, you might see mostly colorful males out and about.

A goldfinch, a chickadee and a house finch share a bird feeder in December. (Photo: Richard George)

Female house finches are brownish; males can have a reddish face and upper breast, depending on diet. The red coloration comes from carotenoids in berries and fruits, and the male can be colored from pale yellow to deep red. The more carotenoids in its food when it is growing new feathers, the deeper the male’s coloration. Female house finches are most attracted to males with the deepest red pigment. (Male house finches in Hawaii – called the papaya bird – never turn red because their favorite food is the papaya, which has no red pigments.)

A group of finches is called a charm, and house finches are one of the more charming bird species. Once popular as pets, their adaptability has allowed them to thrive in many environments to which they have been introduced.

You typically see more male house finches than females in winter. Here a male house finch perches on a snowy February day. (Photo: Richard George)

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Jeanine Farley is an educational writer who has lived in the Boston area for more than 30 years. She enjoys taking photos of our urban wild things.