Birding: Subspecies within a species

‘Texas’ lesser goldfinch has a jet-black back.  (Eric Moore/Courtesy)

‘Texas’ lesser goldfinch has a jet-black back. (Eric Moore/Courtesy)

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The “western” lesser goldfinch has a greenish back. (Eric Moore/Courtesy)

When referencing field guides it is not uncommon to see wild bird species divided into subspecies, which are frequently referred to as “races.”

For instance, if you were to look up fox sparrow in “The Sibley Guide to Birds,” you would see that this species is divided into four different subspecies or races. Yet, at this point in time, all of the different subspecies are still considered to be just one species — fox sparrow.

For example, fox sparrows occurring along the west coast are referred to as the “sooty” fox sparrow. Fox sparrows occurring in the California interior are referred to as “thick-billed” fox sparrow. The interior west race is referred to as a “slate-colored” fox sparrow. And finally, the eastern race is referred to as the “red” fox sparrow.

While all of the different subspecies are currently lumped together into one species, there is the possibility that at some point additional scientific study might result in some, if not all, of these subspecies being broken out into their own separate and unique species.

Did you know there is a wild bird species in our area that has more than one race? It is our very abundant lesser goldfinch. Most of us think of male lesser goldfinches as having a greenish back with a black patch on the crown of the head, and prominent white patches in the wings that are especially visible in flight. This is considered the “western” race that we typically see here in the Central Highlands area of Arizona.

However, there is a subspecies of lesser goldfinch shown in the Sibley Guide referred to as the “Texas” race. Males of the Texas race have an entirely black back instead of a green back. It is actually a very striking bird, with the vivid contrast between its lemon-yellow breast and its jet-black back.

This week I had a male Texas lesser goldfinch in my yard competing for a vacant spot on the nyjer feeder (good luck with that!) and it stood out as being so different from all of the other western lesser goldfinches at the feeder.

It was fun to see the variation in plumage and coloration of the Texas race compared to the western race of this species. I don’t have any scientific numbers, but I am confident that the Texas race makes up just a percent or two of all of the lesser goldfinches we see here in the Central Highlands area.

It is helpful to have more than one field guide when it comes to bird identification, so that you can see the variation in plumage within a species. It is not realistic to assume that all finches will look the same, or all sparrows will look the same, any more than it is realistic to assume that all human beings will look the same — there are many different races within the species of human beings.

Earlier this week, I reflected on how it was exactly a year ago that we released the “Sibley’s Birds of the Arizona Central Highlands” folding guide. The guide has been so well received, and I feel it has been a game-changer in making bird identification easier for the casual, backyard birder.

Now that it is September, I want to promote our ninth annual Wild Bird Photography contest. The submission period started on Sept. 1 and runs through Sept. 30. We encourage anyone and everyone to submit pictures for this fun, annual event. Photo contest guidelines are available for review on the Jay’s Bird Barn website at www.jaysbirdbarn.com.

Until next week, Happy Birding!

Eric Moore is the owner of Jay’s Bird Barn, with three locations in northern Arizona – Prescott, Sedona and Flagstaff. Eric has been an avid birder for over 50 years. If you have questions about wild birds that you would like discussed in future articles, email him at eric@jaysbirdbarn.com.