David L. Trauger Harold A. Doty David E. Sharp Jerome R. Serie 1982 <p>A technique was developed to distinguish yearling from adult canvasbacks (<i>Aythya valisineria</i>) in the field during spring on the basis of white flecking on the distal ends of selected wing feathers. Covert feathers from adults had well-defined vermiculation patterns whereas feathers from yearlings lacked such markings. These age-related characters were confirmed by paired comparisons of feathers from the same captive birds in consecutive years and by discriminant analysis of feathers using densitometric measurements from known-age wild birds. Reflective densitometric measurements of greater secondary coverts for females and males were significantly different between 1- and 2-year-old and between 2- and 3-year-old canvasbacks. Greater secondary coverts were the best feathers for recognizing age-classes of males and females. Densitometric values indicate low variability among different observers and within samples.</p> application/pdf 10.2307/3808222 en Wiley Age-class determination of canvasbacks article