Wednesday, May 30, 2007

A stretch of river XL: Wood Ducks and their cold feet

Here along the Little Arkansas, the waterfowl (identified here) seem especially plentiful this spring. We already have several broods of mallard ducklings and goslings, and the wood ducks' broods have yet to hatch.

The Wood Ducks. They perplex me. The Canada geese and the mallards will regard Scruffy and me as we approach with a watchful gaze, often letting us approach to within 20 feet before they move or fly away. The wood ducks have far less tolerance for our approach, though, even when, as they tend to do, they are foraging amongst the Canada geese, as if using the taller birds as their lookouts. If I had to guess, they've never let us approach closer than 30 or 40 feet before they suddenly take flight, their call sounding like nothing so much as a squeaky hinge on a cabinet door.

In fact, it is their skittishness that prompted this post.

I've been known to spend a little time writing my posts, but I've never tried anything nearly so ambitious as those that Hank regularly writes over at A Lake County Point of View (his most recet post, here, is one of his shorter efforts). Without going into detail here, I'll just say I have even greater respect for what he does than I did before (which was already considerable).

Here is what cost me the most trouble for this post--and this, by the way, is the sort of thing Hank writes most brilliantly on: The wood duck's scientific name is Aix sponsa (only it and the Mandarin duck are of genus Aix). Why "Aix," I wanted to know, and not "Anas," the genus of mallards and teals? Because the wood ducks are perching ducks? But maybe even that question will disappear in time; according to the Wikipedia article on family Anatidae, there's apparently some argument over whether Aix is in fact a distinct genus. All I can tell for sure is that at the level of sub-family, what determines these distinctions are feeding habits.

All that, and I still hadn't learned what their scientific name means. The explanation for their common name (they're also known as Carolina ducks, I learned today) is available in various places on the Web: They nest most often in the hollows of trees, often over 100 feet off the ground. Here along the river, there are several very large cottonwoods and sycamores with just such hollows, and I've often seen wood ducks perched in these trees. They would prefer to be nesting in a more heavily-wooded area, I would assume; but, on the other hand, they seem more numerous this spring than last.

But why "Aix"?--meaning, why a Greek name? Dunno, unless, as I said earlier, the idea is/was to distinguish this sort of waterfowl from those of the genus Anas, which also means "of or pertaining to water." I'm certain the explanation is out there; I just never ran across it in several hours of fairly diligent looking.

The answer to the question of sponsa was more forthcoming, though. Several sites provided the information you can see here: sponsa is Latin for "betrothed" and refers specifically to the male's gaudy plumage, reminding someone of a groom's regalia for a wedding.

It's been my observation, incidentally, that of the two sexes, the males are the more skittish.

4 comments:

Pam said...

Our ability to rapidly (in a relative sense) sequence the genome of organisms has turned traditional taxonomy upside down - practical, phenotypic traits that we used to classify organisms together have proved misleading from a genomic perspective - the phylogeny that is emerging is fascinating and I'm guessing that the tree of life that is evolving will be filled with stories. At the most recent American Society for Microbial annual meeting, one of the predominant microbial phylogenists wants to dissolve one of the three major trees of life - the prokaryotes - due to the wide range of genomic diversity within the group. Some of them are more different from each other than they are from the other two trees of life (eukaryotes and archaea). I suppose the moral to the story is that a microorganism isn't always just a microorganism.

Oh, and I'm assuming Scruffy was on a leash? My dogs daydream of a leash-free afternoon on a river like yours.

John B. said...

Pam,
I'm glad you came by to comment on this post. I know enough to know that genome-sequencing is going to reshape taxonomical systems--and that's all I know. So thanks for the anecdote.

It seems odd to sort sub-families not by physical attributes but by feeding behaviors. But then again, in the old days there were only so many ways to make distinctions between/among species that were otherwise very similar to each other.

If Scruffy weren't on a leash, he'd just go completely nuts. He's not by any means dangerous, but he's not the best-behaved dog, either. Squirrels are what get his doggie-propeller going; ducks and geese don't hold as much interest for him. As for you and your dog, I'd assumed you lived close to the water. Apparently not . . .

Winston said...

John, your scope and reach never cease to amaze! Now it's JohnB the naturalist and bird watcher. Can't help with the Aix question...

John B. said...

Winston,
I think I'm a more-successful observer of shopping-carts, personally. But thank you, though.