Posted by Tony Leukering (18.104.22.168) on November 07, 2001 at 21:32:23:
Once we know that these birds are goldfinches, all that is required is to look at the undersides of their tails. The left bird's tail is mostly hidden, but reveals a very important clue. R6 (the outermost rect) has a blackish outer web and a whitish inner web, with the white extending to the tip of the feather. Since Lawrence's has white on the tail restricted to an inner-web mid-tail bar, the left bird is obviously not that species. Lesser females don't have white in the tail, so if it were that species it would have to be a male. However, males have outer rects that are mostly white, except for a thin, black fringe on R6. Thus, this is an American. David Fix's comments point out most other plumage features supporting that ID.
My first thought on the right bird as the pic was loading was that this was going to be a trick, like many that Joe has played on this site. The body just seemed too obviously a "Larry" to be the right answer. However, the undertail pattern is perfect for a female Lawrence's -- a whitish inner-web (visible on the folded tail only from underneath) mid-tail bar. The body plumage is supportive of that ID.
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