The Nature Writers of Texas

The best nature writing from the newspaper, magazine, blog and book authors of the Lone Star State . . .

Thursday, February 26, 2009

Purple vs. House Finches
by Ro Wauer

A February 10 article in the Victoria Advocate, titled “Birds Shifting North,” with a subtitle “Global warming cited for changes in migration routes,” contained a couple issues that need to be clarified. Firstly, the National Audubon Society study that was mentioned did not suggest that birds are changing their migration routes, but only that several species are beginning to spend their winter months further north than they had in earlier years. Secondly, and totally different, I could not help but wonder how many folks, after seeing the photo of a purple finch, might misidentify our local house finches. Although purple finches do rarely winter in South Texas, the closely related house finch is far more numerous.

The article pointed out that global warming was the cause of many birds shifting their wintering grounds further north. The authors pointed out that the average January temperature in the U.S. has increased from 27 degrees in 1966 to 34 degrees in 2005. The northward shift is indeed a fact, and I suspect that many of our wintering birds that we did not see a few years ago but are now found regularly are the result on climate change. According to the article, the poster bird for this shift is the purple finch that now “winters more than 400 miles farther north than it used to.”

The central reason for this nature note is to discuss the differences between the two finches, so that purple finches will not be reported for what are actually house finches. The two species are not that different, so they could be confused. The females, in particular, are very similar, as both possess streaked underparts. However, the head pattern of female purple finches possesses a broad line through the eye edged with broad whitish bands. Female house finches lack the bicolor head pattern and they are not as bulky as their cousins. Males also have similarities, in that they both possess reddish heads and streaked backs. The head, throat, and back colors of adult male purple finches is more a burgundy-red, while the head and throat of house finches is more a true red color. Plus, male house finches possess a streaked belly and flanks; that of the purple finch is spotty.

There also is a third finch, the Cassin’s finch, that has a number of similarities, but it is found only in the West. In Texas, Cassin’s finches are found only in winter and only in the mountainous areas of the Trans-Pecos. While wintering purple finches are now rare in South Texas, house finches, a species that has a western affinity, has increased in our area in recent years. And they also are increasing in the eastern United States. While it was a rarity when we lived in Washington, D.C. during the 1980s, it is now commonplace there.

All three of these finches are closely related, classified in the same genus, Carpodacus. And they belong in the family Fringillidae that includes goldfinches, siskins, crossbills, and redpolls. The majority of these are of northern affinity. The only two of that breed in South Texas are the house finch (its scientific name is Carpodacus mexicana) and the lesser goldfinch (Carduelis psaltria) that is only an occasional visitor to Victoria County but more common to the south and southwest.

1 Comments:

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