BLACK DUCK 
Age Determination 
Tertials that are small and much faded and/or frayed at the tips 
are remnants of the juvenile plumage. Adult tertials and tertials of 
the first winter plumage are larger and are unfrayed or not faded. 
Tertial coverts that are narrow and much frayed and/or faded are also 
presumed to be remnants of the juvenile plumage. Adult and first 
winter plumages have wide, unfrayed and unfaded tertial coverts that 
are broadly rounded. 
Middle coverts of the juvenile plumage are narrow, and somewhat 
trapezoidal. Middle coverts of adult and first winter plumages are 
wider and smoothly rounded. The juvenile tertials and tertial coverts 
are present early in the season (October) and to a lesser extent until 
the end of the hunting season. Juvenile middle coverts appear to per- 
sist, at least in part, until the end of the season. The best place 
to look for juvenile middle coverts is just anterior to the tertial 
coverts. 
KEY TO BLACK DUCK WINGS 
Age Determination 
1. Tertials: 
(a) Very small and narrow, and/or with frayed tips ----- Immature 
(b) Not noticeably small or narrow, never with 
frayed tips ---------------------- 5-2 ~~ ee 2 
2. Greater Tertial Coverts: 
(a) One or more of the most proximal much faded, 
or frayed, and obviously remnants of 
another plumage -------------6--+-------2------------ Immature 
(b) All uniform, not frayed or faded --------- ween enn n- 3 
3. Primary Coverts: 
(a) Four most distal conspicuously edged light 
on their inner webs ---<----=-------<-------8------- Immature 
(b) Four most distal not edged light on inner webs ----- 4 
