Raj, Richie has a lot of expertise about birds. I don't know that much about this subject, so I don't know whether he or you is right. Think however that the 'greenfinch' doesn't matter that you've called it 'siskin' by you as long as the feeder is filled, lol.
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Not being familiar with the term siskin I researched it and found out they are finches. It did resemble our little goldfinches particularly the females. I know it's happy with a full feeder - an excellent capture Raj with beautiful bokeh.