Archive for Sunday, January 11, 1998

BIRD OF THE MONTH: THE HOUSE FINCH

January 11, 1998

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House finches are relatively new to the neighborhood.

When my family and I moved to Kansas in 1958, we noticed no house finches in Lawrence. We knew the species was abundant in town and country out west, especially in coastal California and southern New Mexico. It was not long, however, before house finches became nesting birds in Kansas and were found in most of the state.

They now can be seen regularly, males giving their complex, warbling songs from treetops and small flocks foraging for seeds in the spaces between street bricks or visiting backyard feeders.

How house finches came to be common Kansas birds is of more than passing interest.

A fowl of the law

The story has two lines, one eastern and one western. House finches had been part of the caged-bird business for decades, and captives in the United States were usually said to be from Mexico (where they have a long history as caged birds) or offspring of such captives, since house finches may not legally be captured in the United States.

But some were trapped in the late 1930s in the Los Angeles area, and transported to Long Island, N.Y., for sale. A good number of them were released from captivity in 1940 by pet store dealers aiming to avoid federal prosecution for violation of the Migratory Bird Treaty Act. The house finches nested and reproduced on Long Island and the area with modest success for the next 20 to 30 years.

In the 1970s these eastern house finches passed some sort of ecologic threshold. Their populations increased dramatically, and the species began to spread rapidly from eastern New York. By the 1980s, house finches were in Missouri, moving toward Kansas.

Prior to the release in New York, the distribution of house finches was in the western half of the United States and much of Mexico. In 1903 F.H. Snow said the species was accidental in Kansas, with the first sighting in the state recorded in 1882. By the 1940s, W.S. Long said that the species was a common resident in the southwestern corner of Kansas; since then it has come to occupy most of the state.

A fine distribution map showing annual occurrences farther east in successive years was presented by M.C. Thompson and C. Ely in their recent "Birds In Kansas, Volume 2." From this we know that house finches from Colorado and western Kansas had gotten at least as far as Douglas County before the finches from the east arrived. Whether the house finches now nesting in far eastern Kansas are of the western or eastern stock is unknown. Perhaps our birds represent both stocks.

Christmas Bird Counts by members of the Kansas Ornithological Society now cover much of the state, and from them it is clear that house finches may be seen virtually anywhere in Kansas in winter. This strongly suggests that our house finches are not migratory. Those from Colorado are not classical migrants either, although finches nesting at higher elevations in the Rocky Mountains move to lowlands in winter.

Since eastern house finches became migratory after their release in Long Island, we may have a clue to the source of house finches in eastern Kansas: They probably are from Colorado. This remains to be seen, however, and it is possible that we will need genetic data to settle the issue.

It is clear, however, that local house finches occur irregularly at their usual haunts in winter. They stay in roving foraging flocks until spring. Later, adult males and females will return, frequently to the general area they nested in the previous year. Some individuals actually return to the same nest site. Young of the year disperse in late fall and winter, some moving long distances. Such distances were important in the rapid colonization westward by the species from New York.

Red hot love

The red or reddish feathers in the plumage of male house finch is a striking field mark for bird watchers, and is very important to female house finches. Given a choice, females will choose the reddest male when forming a breeding pair. Females judge the physical condition and overall quality of males by their plumages.

Certainly, the red color is an index to how the male has been feeding, because the red pigments are acquired from what they eat. Orange or yellow males are seemingly perceived by females to be off their feed for some reason, and, whatever the reason, to be avoided during pair formation.

The food of house finches is almost exclusively vegetable matter, and plant sources of reddish pigments, carotenoids, are not uncommon. At least after the annual molt, carotenoids must be present in diets so that red pigments can be laid down in the growing feathers. This happens in most populations so regularly that virtually all adult males wear red plumage. But when diets are deficient in carotenoids, entire populations of house finches may lack any red, such as those introduced into some of the Hawaiian Islands.

House finch parents also feed their young on plant matter, which is unusual for even for normally granivorous birds. One unpremeditated consequence of a vegetarian diet is that cowbird parasitism is unsuccessful in house finch nests. The young of brown-headed cowbirds need animal protein to develop normally, and without it die shortly after hatching. House finches experience some cost when cowbirds lay eggs in their nests, but manage to escape the more costly and debilitating experience of feeding a young cowbird that may be twice the size of an adult finch before it leaves the nest.

Feeder foibles?

House finches have recently acquired an infectious bacterial disease, one involving mucous membranes and joints. Its most evident symptom is conjunctivitis, but the infection may well be systemic. The disease is caused by a bacterium, Mycoplasma gallisepticum, which may be picked up via the respiratory tract or by physical contact. Infected individuals may suffer such swollen and encrusted eyelids that they become functionally blind.

The role of artificial feeding stations in spreading mycoplasma (as well as other diseases) is a current topic of discussion, because feeders can become littered with disease organisms, and frequency of physical contacts between birds is increased at sites where food is concentrated. Mycoplasma infection has appeared in at least two other bird-feeder species -- the American goldfinch and the downy woodpecker -- but is also known from parrots, hawks, gallinaceous birds (from which it was first isolated) and a number of songbirds.

One might regularly clean and disinfect a feeder, place food in places unlikely to be contaminated by fecal material, and cease feeding for a week or so if many bird deaths are noted.

Mycoplasma infection aside, house finches are beautiful and lively additions to the Kansas bird scene. Additionally, the full story of the source (or sources) of eastern Kansan finches is yet to be uncovered. The story is bound to be an interesting one; perhaps some local birders with suitable cooperation from avian geneticists could secure blood samples for biochemical analysis. A minuscule amount from a dozen birds here along with samples from Colorado and eastern Missouri could probably tell us what we want to know.

-- Richard F. Johnston, is professor emeritus at the Kansas University Natural History Museum and a member of the Kansas Ornithological Society.

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