BLACK DUCK (continued) 
5. Tertials: (continued) 
(a) Taper to a point, outer web "pearly" colored -------- 6 
(b) Blunt tip or more abruptly pointed, outer 
web not pearly -<- nner rrr rrr nnn rrr ene tere nen een- Adult Female 
6. Greater Tertial Coverts: 
(a) Three most posterior coverts widely edged 
with two shades of edging --------------9------------ Adult Female 
(b) Three most posterior coverts not widely edged 
usually one shade of edging ------------------------- Adult Male 
GADWALL 
Sex Determination of Adults 
Adult male tertials are long, acutely pointed and silver-gray. Adult 
female tertials are shorter, more bluntly pointed, and silver-brown with 
cream colored tips. Adult male greater tertial coverts are part black and 
part gray, rarely with traces of white tipping. Adult female greater 
tertial coverts are similar but usually much tipped with white. Adult 
male middle coverts consist of some black and some chestnut coverts but 
none of these are edged. Adult female middle coverts generally contain 
some black and some chestnut coverts but these are much restricted to the 
posterior 3 or 4 rows. Coverts in the remaining rows are edged, without 
internal marks, or with wide arcs or bars. The lesser coverts of adult 
males are unedged but with arc and fleck patterns, or rarely plain. 
Lesser coverts of adult females are similar to the middle coverts and are 
edged and plain, or edged but contain wide internal bars or arcs. Adult 
male wings are usually 265 mm. or longer, and adult female wings are 
usually 263 mm. or shorter. 
Sex Determination of Immatures 
Juvenile tertials of both sexes are short, bluntly pointed, and 
usually much frayed and faded at their tips. Late in the season these 
tertials are replaced by feathers similar to those of adult birds of a 
given sex. Immature female wings usually lack chestnut middle coverts 
and often have flat or U-shaped patterns on these feathers. Immature 
males generally have some chestnut middle coverts and tend toward more 
complex patterns. Wings of immature males generally measure 260 mm. or 
longer, those of immature females 259 mm. or shorter. The greater 
tertial coverts of both sexes are part black and part gray and generally 
tipped with white. 
