Sunday, December 11, 2011

Dabbling Ducks - Genus Anas - No. 3

This is the third introductory post on Dabbling Ducks (“puddle ducks”) - Genus Anas. Next will come the “female quizzes.”

The three ducks in this post have generated taxonomic discussion over the decades. Mallard, American Black Duck, and Mottled Duck have sometimes been classified as subspecies of one or the other. It is quite apparent in looking at them that they are closely related, in spite of the Mallard’s flashy dress. The species accounts in Birds of North America does suggest that these three species may constitute a kind of “super species.” But that discussion I will leave to the taxonomists.

As I maintained in a post in November, the drake Mallard is one stunning dude. He is often ignored because he is so common. He is also hardy; he will winter far to the north, so long as there is open water. The drake in this photograph not only is showing off his finest go-on-a-date wardrobe for impressing the ladies, but trying his hand at the precarious northern winter sport of ice walking.
Mallard - drake. (Brattleboro, VT, early February)

Mallard - drake & hen. (New Jersey, late October)
The Mottled Duck looks like a Mallard that forgot to dress up for the party. This Genus Anas species is southern, found in Florida and along the gulf coast, with some introductions in Georgia and South Carolina.

Mottled Duck (Florida, late February)
The Mottled Duck has a problem. Mallards are the origin species for domesticated ducks, and are so adaptable to human presence that they sometimes domesticate themselves. They are also favored as duck pets, until people tire of them and let them go. Feral Mallards are becoming common in Florida and are interbreeding with Mottled Ducks so often that some researchers are concerned that the gene pool will become so mixed as to threaten the status of the Mottled Duck.

Mottled Duck (Florida, late April)

I am not going to try to distinguish the drake and the hen. They know the difference. I refer you to the species account in Birds of North America - BNA - (on line subscription available at Cornell Lab of Ornithology - Subscribe.)

Mottled Duck (Florida, late February)

I am going to do the same cop-out on male/female American Black Duck, and make the same reference to BNA. Essentially, there is no sexual dimorphism in the American Black Duck and the Mottled Duck. Well, maybe not a complete cop-out. In the pair photo, the duck with the darker beak is probably the female.

American Black Duck (New Jersey, mid November)
American Black Duck - drake & hen (darker bill) (New Jersey, late October)

There is one additional Genus Anas species which is resident in North America - Cinnamon Teal. I don’t have any acceptable photos of this duck. Maybe after my winter trip to New Mexico. The Eurasian Widgeon is a regular winter visitor along the Pacific Coast, and regular, but rare, visitor along the Atlantic Coast. I have no photos of this duck. For accidentals in Genus Anas, of which there are several, you are also on your own.

Good Birding!!

1 comment:

eileeninmd said...

Fantastic post on the ducks. And awesome photos for comparison.


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