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House finches (Haemorhous mexicanus) are small songbirds. Males have rosy red heads and chests, while females are brownish. These birds are native to the American southwest and Mexico but are common in our region today.
Back in the 1930s, California bird dealers trapped and shipped thousands of house finches to Eastern states illegally at the wholesale price of $35 per 100 birds. Pet stores sold these birds as “Hollywood finches” or “California linnets.” People liked to keep the male birds as pets because of their colorful plumage, their cheery, twittering song and their active, social nature.
Selling migratory birds was against the law, and in 1940, an angry birder, Edward Fleisher, in Brooklyn, New York, alerted the National Audubon Society of 20 house finches for sale in a local pet store. According to Fleisher: “I wrote to the National Audubon Society asking them to take some action.” Fleisher learned that the birds had been sold by a California aviary. Some authorities claimed that the sale was not illegal because “the species is not protected in California nor is it native to New York State.”
Fleisher then wrote to the Bureau of Biological Survey, where workers told him that house finches were migratory birds, and that the Migratory Bird Treaty Act of 1918 prohibited their sale. Thereafter, the National Audubon Society began investigating. It telephoned 20 bird dealers in the New York area. All the dealers said that they either sold house finches or had in the past. (Three dealers had stopped selling the finches because they did not live long in captivity.)
One wholesaler in California supplied most of the birds. This wholesaler thought he might be able to get around the house finch ban by calling the birds purple finches, which were not migratory and therefore not protected by the Migratory Bird Treaty Act.
One California shipper stated that he had shipped thousands of the birds to almost every dealer in “nearly every state east of the Mississippi.” He also stated that “only about 100 females were shipped to every 1,000 males,” since the males were the highly desired, colorful ones. The shipper estimated that he had shipped east 100,000 or more of these finches.
Once authorities cracked down on this illegal trade in 1940, pet shop owners in New York released their birds into the wild to avoid penalties. In April 1941, two birders spotted a male house finch on Jones Beach in New York. In 1942, people spotted a small flock of birds on Long Island as well as a nest of coarse grasses in the center of a pine tree. By 1943, birders confirmed the first house finch nest with youngsters – four in all. In 1944, observers spotted young finches being fed on electric wires. In 1945, people spotted 24 birds; in 1946, 38 birds. By 1951, scientists documented 280 house finches in the New York area.
The eastern house finch population continued growing. Before long, the birds reached the Connecticut coast. They spread along the Connecticut River valley into Massachusetts. In 1957, a house finch was spotted in Sheffield. In the following year a single bird was spotted in Weymouth. In 1964, single birds were spotted in Easthampton, Nahant, Chelmsford, Needham and Concord. By the 1970s, the population exploded into the Pittsfield and Worcester regions. Today house finches are common in residential areas throughout Massachusetts.
The eastern house finch population also spread west until eventually the eastern birds commingled with their western relatives. House finches are now found in every state except Alaska. (Yes, house finches even made it to Hawaii. Someone from San Francisco brought house finches to Oahu before 1870. By the 1900s, they were thriving on all the major islands.)
Scientists noted, however, that house finches in New York seemed to be darker than those in California. Since some breeders had mated female house finches with canaries to increase the supply, scientists wondered if the birds on the two coasts were indeed the same species. Other scientists thought the East Coast birds were simply sooted, meaning the feathers were covered in black grime from industrial pollution.
To find out, scientists collected and washed birds in New York. They found that the New York birds had dirty feathers. When scientists compared the clean New York birds with birds in California collections, the New York birds matched perfectly with birds from the Los Angeles area. (DNA analysis has since suggested that house finches in the Eastern United States are descended from a population near Goleta, California. And in fact, there were enough finches released in the East that the population has not lost its genetic diversity.)
Most seed-eating birds supplement their diet with insects in the spring and summer. House finches, however, are total vegetarians year-round. Almost all of their diet is made up of seeds, buds, fruits and leaves. In the east, these released birds ate weed, grass and chickweed seeds, as well as the fruits and berries from flowering shrubs. In winter, the birds ate sumac berries. In extremely cold weather, they depended on bird feeders, where they gathered to devour their favorite snack: sunflower seeds. By May, food became available again, and the birds left the bird feeders.
House finches on the East and West coasts have many similarities. Their nests all have a sturdy base and an overhang that shelters the nest from the sun and rain. Females on both coasts prefer males with larger and brighter red patches, which is a sign of good health. The red patches come from the carotenoid pigments in food they eat. The more pigment he eats, the redder the male becomes. (In captivity, male house finches often have orange or yellow patches – a sign that they are eating differently than in the wild.)
But house finches on the East and West coasts have also evolved differently. East Coast finches now have longer beaks than California birds but shorter wings, tails, feet and toes. Climate differences have promoted migratory behavior in some of the Eastern birds. The house finches released on Long Island were nonmigratory, although they did travel locally in winter to find food.
In Massachusetts, house finches are partial migrants. Some migrate south, but others do not. Among migratory birds, females and youngsters migrate farther than males. In winter, banded Massachusetts finches have been documented in Maryland and Virginia. Migrating birds travel farther south in colder winters. Nonmigratory birds often spend winters at bird feeders. This winter, put out sunflower seeds and watch for colorful male finches at your bird feeders. (But be sure to clean your feeder regularly to prevent the spread of diseases.)
Have you taken photos of our urban wild things? Send your images to Cambridge Day, and we may use them as part of a future feature. Include the photographer’s name and the general location where the photo was taken.
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.
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