The Band-tailed Pigeon is named for the light banding at the end of the tail feathers, visible in the back view in the pictures below.
"It is the biggest pigeon in North America, averaging 34 to 36 cm (14–15 in) long and weighing 250–450 g. The plumage is gray, somewhat darker above. The head and underparts have a faint pink cast, especially in the adult male; the belly is nearly white. The distal half of the tail is also pale (except in the subspecies of Baja California), whence the English name. The bill and feet are yellow, good identification marks at sufficiently close range. Adults have green iridescence on the back of the neck, adjacent to a thin white collar on the nape. Juvenile birds have white feather edges above, giving a scaly appearance" (from the Wikipedia article on the Band-tailed Pigeon).
See also the All About Birds page on the Band-tailed Pigeon.