Fine weather continued here in San Antonio today, allowing both garden work and some brief birding. First arrival was another new species for San Antonio, the Thick-billed seed-finch (Oryzoborus funereus). I was still bleary-eyed early in the morning when a female (or possibly immature male) crashed into the window. It was only a little stunned and soon recovered, allowing a brief photo shoot. The best I could do with my tiny camera is what you see above.
In our area, if you see a small bird on the ground or by the roadside and it’s a seed nibbler, it’s almost always going to be the Rufous-collared sparrow (Zonotrichia capensis) or the Yellow-faced grassquit (Tiaris olivaceus). The former, with its crest and striped head, is easy to identify, although the juvenile may give the impression of a Song sparrow or Lincoln’s sparrow because it lacks the rufous and has streaks on the breast. The crest may or may not be raised.
You can forget about the Lincoln’s and all those other north American sparrows, however. They are simply not here, despite the recent discovery of a Clay-colored sparrow down at CATIE. This is a first for Costa Rica, I believe.
The grassquit can present identification problems. The male is easy, with his pretty, yellow-and-black face, but the female’s face pattern is not so distinct and so you get a small, dull-olive bird that can easily be confused with the females of other, similar species.
The only other similar-looking species commonly in our area is the Variable seedeater (Sporophila americana), Caribbean race of course. It is vastly outnumbered by the previous two species. I find the all-black male virtually indistinguishable from the male Thick-billed seed-finch, and so I have the feeling that some of the male seedeaters I see may well be seed-finches. I have not found it easy to pick out whether the culmen is straight or curved, which is the principle field-note difference referenced in Garrigues & Dean. The warm brown of the female Thick-billed seed-finch is a clincher, however, since the female seedeater is very pale. And if you’re wondering about the White-collared seedeater (Sporophila torqueola), I have seen this species here only in cages. It is said to have been common in the area years ago but it has been relentlessly pursued for the cage-bird trade.