Has hybridized with C. chloris. Races form two groups, W black-crowned "carduelis group" (also with britannica, volgensis, frigoris, parva, tschusii, balcanica, colchica, niediecki and loudoni) and E grey-headed "caniceps group" (also with paropanisi, subulata and ultima); groups sometimes treated as two distinct species, but they hybridize in N Iran and probably in SC Russia. Race brevirostris, described from Baki (E Azerbaijan), is poorly differentiated, also name invalid, as preoccupied, and synonymized with loudoni; likewise, major (described from Turkestan) preoccupied, and replaced by new name frigoris. Fourteen subspecies recognized.
Introduced (nominate race) in Bermuda, Azores, Cape Verde Is, SE Australia, Tasmania, New Zealand, Uruguay, and various parts of USA (established only on Long I, New York).
Food and feeding
Status and conservation
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