Female Thick-billed seed-finch
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.
Juvenile Rufous-collared sparrow with crest 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 dull female Yellow-faced grassquit
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.
