Friday, September 25, 2015

Fri-D: the Teal

Nobody I know really likes female-plumaged ducks. They're just a pain to identify. How many times have I been leading a summer birding tour in the western U.S. and been pressured to find a definite Cinnamon Teal when Blue-winged Teal are also present? Too many.

And by the way, I use "female-plumaged" rather than just "female" for a good reason, since male North American ducks molt into what is known as an "eclipse" plumage in summer, which by modern molt terminology is their "alternate" plumage. Most "alternate" plumages are also "breeding plumages," i.e. the fancier, more colorful plumage, but ducks screw all that up. Someday maybe I'll write a post about telling eclipse plumage male ducks from females, which is not often easy. Witness the regular appearance of female-plumaged Eurasian Wigeons in Cape May that then call like males, and eventually molt into obvious males. In early fall, many male ducks come south looking like females.

Right, so, teal. I'm leaving Cinnamon Teal out of this, since you have to be smarter than me to i.d. a female-plumaged Cinnamon in the east.

Let's pretend you saw the two ducks in the photo next to a Mallard (and they were next to a Mallard when I took this picture, but you can't see it in the photo), and you realized they were little. Green-winged Teal is our smallest duck, averaging a mere 14" in total length. For comparison, an American Robin is 10". Little ducks. Blue-winged Teal are slightly bigger, averaging 15.5". Mallards loom over all three, at 23".

So are these two ducks the same species? Well, no, but if you dialed in on the green patch on the wing of the front duck, beware. Both Green-winged Teal and Blue-winged Teal have green secondaries (much more prominent on the male BWTE than the female, which shows hardly any green.) Also, it is important to remember that, unless a duck is flying or preening or otherwise opening its wing a little, you can't see its flight feathers at all, because the whole wing is buried in the body plumage and under the scapulars and tertials. Are we having fun yet?

An excellent place to start with any bird identification is the bill. As an aside, in female ducks, bill color and pattern is often very useful.  These two both have dark bills, but flick your eyes back and forth between the two. That back bird has a big, thick bill compared to the one in front, doesn't it?

Another excellent place to start with any bird identification is the exact face pattern (the warbler face plate in the old Golden Guide remains one of my favorite pieces of bird art). The front bird has a dark line through the eye. The back bird does too, though arguably a little less distinct, but it also has white eye-arcs and a white smudge at the base of the bill. What are male Blue-winged Teal known for? Oh, yeah, that white half moon in front of the eye. . .

Duck butts are also often useful for i.d. The front bird has a buffy horizontal stripe directly beneath the tail, the back bird does not.

So, the front bird is a female-plumaged Green-winged Teal, the back bird is a female-plumaged Blue-winged Teal. Both species are pouring south right now, with many of the Blue-wingeds on their way to South America (most "only" to Central America, some only to the southern U.S.), while the Green-wingeds don't go quite as far, wintering south to Mexico with many wintering in the U.S.

By the way, did you know any duck can be identified, sexed, and aged just by its wing? Also check here . Ducks are perhaps the best known and most studied wild birds. Why? They taste good. . . and are deeply loved by duck hunters, birders, and the public in general.

This photo was taken at Forsythe NWR during my lunch break one day this week.

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