They lay eggs, and most can fly (although many, including penguins and ostriches, cannot). AMERICAN CROW The American crow is the “default” crow across most of North America. It overlaps broadly with the common raven, and to a lesser extent with the Chihuahuan raven, fish crow, and northwestern crow. Study of vocalizations, bill structure and size, tail shape, and overall structure of this species will greatly aid in the identification of other crows and ravens. Regional variation in size of the American crow poses challenges, particularly in the northwest. Polytypic. Length 17.5" (45 cm).
AMERICAN GOLDFINCH The brightly colored male American goldfinch is especially recognizable. The American regularly visits seed feeders, particularly in the east. It is often very gregarious, especially during the nonbreeding season, when it flocks to roadsides and brushy fields to feed on thistle and sunflowers. It is often heard in flight, giving distinct flight calls. Polytypic (4 named ssp.; differences slight). Length 5" (13 cm).
MAMMALS * are warm-blooded, and are nourished by their mothers' milk; most are born live (however, the platypus lays eggs). Most mammals also have body hair.
No animal has a more distinctive coat than the zebra. Each animal's stripes are as unique as fingerprints—no two are exactly alike—although each of the three species has its own general pattern.