Ordinary yet interesting

One of the more common and less interesting-to-look-at local birds turns out to be one of the more interesting birds to study. With its relative plainness and its abundance, it’s a species easily taken for granted. Even its name – house finch – is mundane, but it has a storied past.

The house finch was originally a bird strictly of the West, first discovered in 1776 in Mexico and later found to inhabit most Western areas from the Rocky Mountains to the Pacific Coast and from Washington and Idaho south into southwestern Mexico.

In 1859, a few birds from central California were released on the Hawaiian island of Oahu. House finches have long since been abundant on all of the Hawaiian Islands. In the overall history of the species, that wasn’t such a big thing. House finches are naturally found on many Mexican islands.

But in 1940, someone did a small thing that has turned into a huge thing. A few house finches, probably from Los Angeles, were released on New York’s Long Island. Prior to that time, there were no house finches east of the western Great Plains.

It’s not so surprising that house finches would be taken to New York. They have been a favorite cage bird in Mexico almost since being first discovered. As a pet, the house finch is known as the Linnet. However, in the United States, it is illegal to keep house finches as cage birds, and to transport them anywhere.

In 1940, word reached one or more pet stores on Long Island that they were about to be raided because of what they billed as their Hollywood finches. So, the birds were released.

A nest was found in 1944. House finches were seen in New Jersey in 1948. The species dispersed rapidly to the south and west, and slowly to the Northeast.

By the end of its first 50 years as an Eastern species, the house finch had reached as far north as southeastern Canada, as far south as the Gulf Coast, and as far west as North Dakota and Oklahoma. At the same time, the original Western populations were spreading out as well, into the Great Plains in the east, and deeper into British Columbia to the north.

Currently the house finch breeds in 49 states and in all the border provinces, and there is a sight record of a house finch in Alaska. It is estimated that the current population of house finches may be as high as 1.4 billion. The only other species to have such a tremendous 50-year growth spurt in North America was the house sparrow, and it’s now reported as having been displaced in many areas by the expanding house finch population.

It turns out that house finches like people, or at least they like what people do to the environment. People make inhospitable areas, such as predevelopment eastern North America, into ideal house finch habitat.

It doesn’t hurt that the house finches eat almost exclusively weed-species seeds, and that they may produce as many as three broods each year. One fecund pair in Michigan was observed to fledge 14 young one summer. Finches have been known to live for nine years.

Finch census takers have found that finch populations mirror human populations. Where there are the most people, there you will find the most house finches. But the finch census also shows that, aside from the overall range expansion, Western populations are declining while Eastern populations are increasing.

Some ornithologists attribute the decline of the Western populations to a socially transmitted disease. In particular, there is a virus, a pox virus, that is seen in house finches in the West quite commonly.

The virus is not, though, seen very often in Eastern or Hawaiian finches. No one knows why. It may be that it hasn’t gotten there yet, or the newer populations may be genetically stronger – although both the Eastern and Hawaiian populations originated in California, so that seems unlikely to me.

Infected birds develop swollen feet and often lose toes. If the lesions show up on the face, the birds become blind. In gregarious species such as house finches, a disease of this type can spread rapidly, thus limiting population. When populations are smaller, the disease tends to disappear. But when populations grow too large, that’s when disease steps in.

The last thing about house finch biology is something that I noticed as a kid, just starting to look at birds. Our family took a trip to Hawaii and I was seeing yellow house finches – yellow, not red. Some had perhaps a bit of orange, but mostly yellow. And I have seen a few yellowish to orangish house finches in the Northwest, too.

How do they do that? Here we do have the answer. The pattern of colored areas on a male house finch is genetically determined. Birds of different areas have consistently larger or smaller patches of color. The color itself, however, comes from what they eat, or don’t eat.

In house finches, red is a carotenoid pigment deposited in the feather structure while the male molts during late summer and early fall. If he eats a lot of carotenoid, he’s bright red; if he eats less, he’s more orange; if he gets none, he’s yellow. It doesn’t matter what he eats other times of the year, it only matters while he is growing his new feathers. Hawaiian birds and a certain population in the Southwest, don’t get carotenoids in their diet and thus remain yellow. With lots of carotenoid, females even turn a little pink.

There is one other oddity to the male house finch’s feathers. When the new feathers first come in, the bird is rather dull and pale. This lasts through the winter. With time, though, the outer, nonpigmented portion of the feather wears off to reveal the brightly colored area beneath. Timing is such that the bird is at his brightest during breeding season.

This is lucky for him because females choose a mate based on color intensity.

Finally, a bit of house finch trivia. This finch is closely related to three other finches with much more interesting names: the common rosefinch, a Eurasian species that is occasionally seen in Alaska; the purple finch, which is not purple at all; and Cassin’s finch, a finch we also see here in North Idaho. All four of these species are in the group referred to as cardueline finches.

OK, that was still biology. Now for the trivia. First, the name finch goes back 3,000 years to when it was initially applied to the Eurasian Chaffinch. The original name sounded like the birds call – a ping, with a hard g. In German it became fink. In Old English it became finc. In new English it is now finch. So, that’s where fink and finch came from.

The other bit of trivia is an observation all my own. This collection of finches is really a group for us to be proud of, as I think that they must have originally been named for our area. Don’t you see the connection, for it’s similar to the origin of the word finch? Remember, these are the cardueline finches. Cardueline and Coeur d’Alene? Do you see it? There are so many wonders to be found in biology.