Excerpts from Jim Conrad's
from the April 7, 2013 Newsletter issued from the Frio Canyon Nature Education Center in northern Uvalde County, southwestern Texas, on the southern border of the Edwards Plateau, USA
Once more below the kitchen window little brown sparrows with striped backs were hopping about pecking at sow thistle fruits, and once more the birds didn't look like the usual Chipping Sparrows. You can see one displaying a conspicuous dark spot on his chest below:
Below is a rear view of the same bird showing his striped back:
Not many sparrow species with streaked chests display such a conspicuous dark spot in the chest's center. Fox Sparrows do but they're more rusty-red overall. The spot suggested that this was probably a Song Sparrow, even though it didn't quite look like the ones I know so well from Kentucky, Mississippi and the West Coast. However, I remembered that Song Sparrows occupy many habitats over a large distribution area from coast to coast in North America, and that consequently 24 subspecies have been recognized -- or 31, 39 or some other number, depending on your expert. Song Sparrows are one of the most regionally variable birds in North America. In general, coastal and northern birds are darker and streakier, while southern and desert birds look paler. These birds outside my window stuck me as being less streaked than what I'm used to.
So, at first I was pretty sure that I had a Song Sparrow, but after I showed the picture around and heard from others knowing this area's birds better than I, I had to change my opinion. It's the Lincoln's Sparrow, MELOSPIZA LINCOLNII; I'm fairly sure now, though it's a tough call.
Often Lincoln Sparrows don't have dark chest spots, but all the ones below my window do. However, from what I can tell, none of the several Song Sparrow subspecies and races display "buffy" chest bands through which the stripes run, as seen on our bird. Song Sparrow chest stripes cross white or only slightly dingy chests, not chests with such warm colors as on ours.
In general, the chest streaking on Lincoln Sparrows also is finer than on Song Sparrow.
Lincoln Sparrows are thought of as one of those species you see only when they pop up from the grass, fly quickly a little distance, then plunge back into the grass where they remain invisible as you fumble with your binoculars. But here they were below my kitchen window feeding on sow thistle seeds.
However, they won't be staying long. Lincoln Sparrows occur in Texas and much of the southwestern and south-central US only during the winter. They nest mostly in Canada and the northwestern US.