 The American goldfinch (Carduelis tristis) can be found all across southers Canada from BC to Newfoundland. In the summer, the male is a bright yellow with a black patch on his head. Later in the year however, the male's plumage fades to almost match the dull olive colouring of the female.
No other finch in the cardueline family displays such a striking difference between its summer and winter colours, the result of a unique springtime moult. This long process may be the reason that the goldfinch is one of the latest breeders in the temperate zone.
Another reason may be the fact that goldfinches feed on seeds from plants like thistles, which are more plentiful in late summer. This food is necessary to provide the energy for breeding and to feed the chicks.
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