Some of you may remember this little mystery bird that I posted on May 30th. I've still been discussing it off-and-on, with all kinds of interesting theories and ideas coming up along the way. At the time of the sighting at Tres Rios, I had been hearing what I thought was a Cassin's Sparrow but couldn't find or photograph anything that fit the bill.
I had no proof or reason to believe that the photographed bird was the one singing, especially since this bird was more or less in the open and I hadn't been able to spot the singing bird at all. My first thought was that it was an out-of-place Rufous-winged Sparrow. A lot of people made strong arguments for Rufous-crowned Sparrow, and since that seemed a more likely sighting in the area, though still unusual, I was slowly pulled in that direction.
Most recently I posted this photo on the Facebook Bird ID group of the world page. It generated another interesting discussion that served as a great review of the arguments for Rufous-winged and Rufous-crowned Sparrows. Then there was an exciting twist when Kenn Kaufman stopped by (always nice to have the input of someone who can say "I've written the book on...") and posited, rather convincingly, that this was in fact a rare rufous morph of Cassin's Sparrow.
All of the sudden the Cassin's song, long forgotten, came back into play. There had been a general agreement that while this bird was kinda Rufous-crowned and kinda Rufous-winged, it wasn't really either. Then this rufous-morph Cassin's idea came along--and I can honestly say I'd never heard of any morph Cassin's Sparrows--which is the identification I'm sticking with for now.
It's nice that I can count Cassin's Sparrow as more than a 'heard only' bird. It's even nicer that this identity crisis and the debate it sparked has helped me learn a lot more about all three contenders than I would have ever learned otherwise.
Thanks to all who participated on the discussion, both earlier on this site and on Facebook. For those of you who are curious, here's a link to the facebook thread: Cassin's Sparrow Talk.