from southern Canada south to Florida and central Mexico. The pale goldfinch (S. t. pallidus) is differentiated from other subspecies by its paler body color, stronger white markings and, in males, a larger black cap. It is slightly larger than C. t. tristis. The summer range is from British Columbia to western Ontario, south to Colorado and west to Oregon. In winter, the range extends from southern Canada and northern California, south to Mexico. The northwestern goldfinch (S. t. jewetti) is smaller and darker than the other subspecies. It occurs on the coastal slope of the Cascade Mountains from southern British Columbia to central California, overlapping with the range of C. t. pallidus. The willow goldfinch (S. t. salicamans) occurs west of the Sierra Nevada range during the summer and in the central and southern Baja California Peninsula to the Mojave Desert and the Colorado Desert in the winter. In winter, the plumage of both sexes is browner than the other subspecies and in summer, the male's black cap is smaller than that of the other subspecies. This seems to be the most ancient extant species of the Meso-American Spinus/Carduelis evolutive radiation, whose parental species is Lawrence's goldfinch (Spinus lawrencei). Description The American goldfinch is a small finch, long, with a wingspan of . It weighs between . Among standard measurements, the wing chord is , the tail is , the culmen is and the tarsus is .} The beak is small, conical, and pink for most of the year, but turns bright orange with the spring molt in both sexes. The shape and size of the beak aid in the extraction of seeds from the seed heads of thistles, sunflowers, and other plants. The American goldfinch undergoes a molt in the spring and autumn. It is the only cardueline finch to undergo a molt twice a year. During the winter molt it sheds all its feathers; in the spring, it sheds all but the wing and tail feathers, which are dark brown in the female and black in the male. The markings on these feathers remain through each molt, with bars on the wings and white under and at the edges of the short, notched tail. The sexual dimorphism displayed in plumage coloration is especially pronounced after the spring molt, when the bright color of the male's summer plumage is needed to attract a mate. Once the spring molt