A System of Age Classification for Field Studies of Waterfowl Broods

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Abstract
A system of age classification for field studies of waterfowl broods is formulated from a study of the growth and plumage development of hand-raised birds. The spp. considered are mallard (Anas platyrhynchos), pintail (Anas acuta), blue-winged teal (Anas discors), shoveller (Anas clypeata), baldpate (Anas americana), canvasback (Aythya valisineria), redhead (Aythya americana), and ring-necked duck (Aythya collaris). A synopsis of weight and plumage development observations is presented in tabular form. Five fairly discreet age classes can be identified in all spp. studied. They are: Class la - early downy; Class Ib - late downy; Class IIa -predominantly downy with noticeable feathers; Class IIb - predominantly feathered with noticeable down; Class III - completely feathered prior to flight. This system is an elaboration of the three-group classification system used by the U. S. Fish and Wildlife Service. A preliminary field trial indicated that most broods can be placed readily in one of the five groups.

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