. Birds of Massachusetts and other New England states. Birds; Birds. 190 BIRDS OF MASSACHUSETTS Subfamily River Ducks. Number of species in North America 15; in Massachusetts 12. Ducks other than the mergansers have rather broad, flat bills. They fall naturally into two groups — the fresh-water, surface-feeding ducks, and the diving or bay and sea ducks. River ducks differ from both mergansers and sea ducks in having no lobe or flap on the hind toe. River ducks get their food mainly in shallow water by tipping up, head downward, which enables them to reach bottom, or by dabbling al
. Birds of Massachusetts and other New England states. Birds; Birds. 190 BIRDS OF MASSACHUSETTS Subfamily River Ducks. Number of species in North America 15; in Massachusetts 12. Ducks other than the mergansers have rather broad, flat bills. They fall naturally into two groups — the fresh-water, surface-feeding ducks, and the diving or bay and sea ducks. River ducks differ from both mergansers and sea ducks in having no lobe or flap on the hind toe. River ducks get their food mainly in shallow water by tipping up, head downward, which enables them to reach bottom, or by dabbling along the margin. All of them, however, can dive in case of necessity and sometimes they do so, but not commonly. Most of these ducks have a note- worthy marking, a brightly colored, iridescent patch on the secondary feathers of each wing known as the speculum. All male surface-feeding ducks of North America (and ap- Foot of River Duck parently females also) undergo a double molt beginning in the season of reproduction. After the first of these molts in summer the male has assumed an inconspicuous plumage (called the eclipse plumage — which is rather brief), usually very similar to that of the female, and after the second molt (out of the eclipse plumage) takes on the usual adult winter or nuptial plumage. In species where the male and female are alike and in females of most species the changed plumage of summer is so much like that of winter that it is not noticeable. During the entire year most of the feathers are shed twice, but "the long scapulars, wings and ventral feathers are renewed only once," being molted among the last of all; young males of the second year molt in a similar manner. The dates of these molts vary much according to the age of the birds or the latitude of the locality. The males usually begin to molt into eclipse plumage in May or June but do not shed all their flight feathers until August. They then are unable to fly. This is often (but per
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Keywords: ., bookauthorforb, bookcentury1900, bookdecade1920, booksubjectbirds
