American Goldfinch (Cadruelis tristis) – and as a birding friend notes, male, in new mating plumage –
All winter these guys have been kind of greenish-yellowish-grayish, like the females. In the past month or so they have molted into this bright lemony suit and their black crowns have returned. The "tristis" in their name comes from the occasional "whiny" tone in their songs, which sounds "sad" to some humans. Mostly, their songs are bubbly and energetic, sometimes virtuoso performances. There is a sporadic, brief but diagnostic "whiny" note that recurs within the song. Also, especially in flight, they sometimes repeat "potato chip, potato chip, potato chip, chip."