
CANVASBACK (continued) 
Like redheads, canvasbacks can be aged largely by tertial coverts. 
These feathers are of three types: 1) adult type, similar to the 
surrounding coverts; 2) adult type, that are obvious replacements; and 
3) juvenile type. Sex also can be determined from the first two, but 
it is usually necessary to refer to the tertials or middle coverts of 
the third type. 
KEY TO CANVASBACK WINGS 
1. Upper Wing: 
(a) All of the following: overall appearance white, 
primary coverts heavily flecked or vermiculated, 
tertials heavily vermiculated with white ---------- Adult Male 
(b) All of the following: overall appearance gray brown 
to heavily frosted gray, primary coverts lightly 
flecked to unflecked, tertials lightly flecked with 
most flecking concentrated near tips or tertials 
.and tertial coverts much whiter and more heavily 
vermiculated than remaining plumage --------------- 2 
2. Tertials and/or Greater Tertial Coverts: 
(a) Much whiter than surrounding feathers, obviously 
partial replacement of juvenile plumage ----------- Immature Male 
(b) Approximately the same color as surrounding 
feathers ------ 22 nen ne nn nee eee neers eeen- 3 
3. Middle and Lesser Coverts: 
(a) Heavily flecked to lightly vermiculated, overall 
appearance heavily frosted gray ------------------- 4 
(b) Unflecked or very lightly flecked, overall 
appearance gray or brownish gray -------ccecrnennn- Immature Female 
4, Greater Coverts: 
(a) Usually well flecked, flecking tends to be more 
spread over feathers than in (b), often indis- 
tinct white tipping over secondaries, very 
ragged and somewhat narrow over tertials ---------- Immature Male 
30 
