other diving ducks. In Missouri they seldom stray far from the Mississippi River. During the migratory peak, canvasbacks sometimes gather in rafts of hundreds of birds.
The redhead (Aythya americana) is the spitting image of the European pochard. At 19 inches, it is only slightly smaller than the canvasback, but its head has a rounded profile, and the bill is more like those of other ducks. Both male and female redheads have bluish-gray bills with black tips.
The ring-necked duck (Aythya collaris) is one of the smallest and most common bay ducks in Missouri. Ringnecks cruise big rivers and lakes, but they also frequent ponds, marshes and managed wetlands. Their small size, together with typical diving-duck plumage and speed, make ring-necks fairly easy to recognize on the wing.
Don’t be confused if you shoot what you think is a ring-necked duck but are unable to find the ring. The name refers to an indistinct band of chestnut-colored feathers at the base of the drake’s neck. A better identifying characteristic is the white ring near the tip of the gray bill. It might have been better named the ring-billed duck.
Greater and lesser scaup (Aythya marila and affinis) look as if they were dressed for a black-tie affair. The drakes’ bold black-and-white markings and their tight flying formations make scaup easy to recognize in the air. Scaup lack the black end and white ring that ringnecks have around their bills, but they do have a black fingernail-like scale at the tip.
Telling the two species apart is more difficult, but not impossible once you see enough of them to recognize the greater scaup’s longer wing patches. These light markings run nearly to the tips on the upper side of greater scaup wings, but only about halfway out on the lesser. Both have the bluish-gray bill that accounts for the nickname “bluebill.”
Unfortunately, most hunters don’t see enough scaup to become proficient at telling the two species apart. For that reason, the bag limit includes both greater and lesser scaup.
Once you have a scaup in hand, you can tell the greater scaup by the rounded profile of its head, or the lesser by a slightly peaked, angular shape. On drakes, look for a subtle green iridescence that marks the head of the greater scaup or the purple sheen of the lesser. Also, greater scaup seldom are seen in Missouri and almost never on wetlands.
Sea ducks—as their name implies—are