To refresh your memory, here is the photo from June’s Bird Quiz. It was taken on South Padre Island, Texas, during the month of December. Don’t read any further if you want one last chance to identify this bird.

If you don’t recognize this as a duck, you might want to review your preschool animal books. It’s true that not all waterfowl are ducks, but with its flat bill this one is unmistakable. So, we have a duck. Which duck is it?

When I first started birding, ducks were my favorites. They were easy to see—floating out there in the water with no leaves and branches obscuring my view. In places frequented by people, the ducks are relatively fearless, so you can get pretty close. They sit there, helpfully staying put while the neophyte flips pages in the field guide. And for the most part, ducks are easy to identify. A Mallard looks nothing like a Northern Pintail.

Then there are the exceptions, and of course I’ve picked one of those for our quiz. But first, a few helpful hints.

While you can’t tell from the photograph, ducks tend to fall into two categories—dabblers and divers. Watch the duck for a bit. Mallards are dabblers. They stay on the surface of the water with their bill just submerged, chomping weeds as they paddle along, as you can see in this photo. Divers, such as Redheads or goldeneyes, do their feeding underwater, disappearing headfirst into the pond just as you finally get your scope focused on them. I’ll give you a clue; our quiz duck is a diving duck.

A quick perusal of your field guide shows that there are a number of black-headed ducks. A Common Merganser has a black head, but it also has a relatively pointed bright orange bill. Cross that one off. Common and Barrow’s Goldeneyes also have black heads, but they have prominent white spots on their cheeks as well. In spite of the yellow eye, this isn’t a Goldeneye.

Now we’ve narrowed things down to the two scaups and a Ring-necked Duck. The latter has a ring on the bill (so explain to me where the name comes from!) and a black back. This duck has a nice gray-blue bill with a black tip and a speckled-barred back. Yup, it’s a scaup.

Now things get interesting. Lesser Scaups are found all over the country, while Greater Scaups hug the coastlines (although they can be seen anywhere during migration). I was on the Texas coast, so that’s no help at all. In fact, I saw both scaups in the same place.

In the right light, a Lesser Scaup’s black head has a bluish tinge, while the Greater Scaup tends toward more of a green-black. Hmmm…  am I imaging a tinge?

According to Sibley, Lesser Scaups have stronger barring on their flanks than do Greater Scaups. This is helpful if you have what you believe to be both species present, and you want to distinguish which is which.

The other most useful difference is in head shape. Lesser Scaups tend to peak at the back of the head, while Greater Scaups peak toward the front. Birds have a tendency  to reshape themselves, stretching, snuggling, fluffing and whatnot, so shape is a tricky field mark. But this duck definitely peaks at the front. I concluded that it’s a Greater Scaup. Compare it with this photo of a Lesser Scaup, with its head pointed to the rear, and barring on the white flanks.

Did you get it right?