CANVASBACK (continued) 
4(b) Usually well flecked, flecking tends to be 
concentrated near ends of individual coverts, 
no white tipping present, smooth and relatively 
broad over tertials --------------------+----------- Adult Female 
GREATER SCAUP 1/ 
Sex Determination 
Scapulars of adults of both sexes may be vermiculated. Those of 
adult males are more white than dark. Those of all females are more 
dark than white. Scapulars of immature males are often female-like | 
but usually have one or more male-like feathers. All adult males and 
many immature males have flecked tertials. Females do not have flecked 
tertials. The greater and middle coverts are plain on most immature 
and many adult females. Those of males are flecked or vermiculated. 
On female wings, flecking tends to be concentrated near the coverts 
edge. On immature males, flecking tends to be recessed from the 
covert's edge. Adult males have vermiculated coverts. 
Age Determination 
Juvenile tertials are frayed to a pointed tip. Usually, tertials 
of the adult plumage have rounded tips. Occasionally, they are similar 
to juvenile tertials. CAUTION: diving duck tertials are somewhat 
unreliable. The greater coverts of adults are smoothly rounded and 
shiny black over the tertials. Juvenile greater coverts are rough, 
often narrower, and dull black. 
Juvenile tertials and tertial coverts are not replaced during 
the hunting season on most birds. 
1/ CAUTION: Age and sex determination procedures for lesser scaup 
are similar but the appearance of wing characters is 
somewhat different. 
31 
