House finches are well adapted for urban living

House finches are the perfect urban bird. They would willingly trade an empty lot filled with grasses and bushes and trees for a nice new house with a bird feeder.

They are fond (understatement) of feeders, and nest readily around and on buildings. They have nested in the hanging flower pots on front porches, for instance.

There is a native population on the West Coast, finches comfortable in open undisturbed desert as well as cities. And there is an introduced population in the eastern half of the country.

A small number of house finches was set free on Long Island in 1940. That population, readily adapting to city life and bird feeders, spread east, eventually arriving here.

Minnesota's first house finch was recorded in 1980 at a feeder in Minnetonka, according to Robert Janssen's book "Birds in Minnesota."

By the 1990s house finches had been seen in each of our 87 counties. Janssen calls it the most rapid statewide invasion of any species known in Minnesota. The birds are semi-migratory, numbers decreasing in winter.

House finches also are among many bird species whose feathers are randomly colored red, orange, and yellow by what they eat.

The key to color is plants containing the chemical carotenoid, a yellow, orange, or red fat-soluble pigment. These also give color to ripe tomatoes and autumn leaves, among other plant products.

Animals cannot synthesize carotenoids, so they get it from what they eat. A wide variety of plants, algae and bacteria contain the chemical.

In the case of house finches the food is sunflower seed. Given the speed at which the finches empty our seed feeders, I'm surprised the birds don't glow.

In addition, a particular component of a bird's diet can do strange things if eaten during molt. Bush honeysuckle berries are a good source of carotenoids. If timing is right, the berries can color the replacement feathers produced by molt in the fall.

In house finches, yellow, orange or red feathers can appear as singles, or in patches on the bird, or can be mixed.

Male house finches vary in color from pale yellow to bright red, color mostly on the crown, eyebrow stripe, throat, breast and rump, with intensity of color varying. Other feathering is brown. A few females will show pale yellow/red marking.

"When first grown, feathers with carotenoid pigmentation are tipped with brown, reducing overall intensity of plumage coloration," according to ornithologist Geoffrey Hill, author of the house finch monograph written for the "Birds of North America" series.

In late winter or early spring the brown tips have worn away, and birds beginning their second spring have feathers of maximum brightness, Hill wrote.

Bush honeysuckle berries give orioles a deep orange color instead of yellow. Yellow-breasted chats can become red-breasted. The white stripe above the eye of white-throated sparrows might have an accent dash of red.

Other bird species show carotenoid colors. The reds of cardinals, rose-breasted grosbeaks, and scarlet tanagers also come from diet, not necessarily including bush honeysuckle, although those berries will brighten colors.

Bush honeysuckle, an invasive, nonnative plant, grows easily in Minnesota, according to the University of Minnesota Extension Service.

(Diervilla lonicera is the native species. Diervilla honeysuckles grow no higher than three feet, have toothless leaves, and berries for fruit. They send up suckers, often forming colonies. Tatarian, Bell's, Morrow's, and Amur honeysuckles are invasive. Tartarian can grow as high as 10 feet.)

Invasive status aside, it sounds like a perfect plant — fast growth in dry to moist sand, loam or clay, in sun or shade, flowers that attract hummingbirds and insect pollinators.

And berries for colorful birds.

Lifelong birder Jim Williams can be reached at woodduck38@gmail.com.