DABBLERS AND DIVERS
by Walter Meagher
photos by Wayne Colony
Ducks are either one or the other: marsh and pond ducks – called ‘dabblers’ – or ducks of deeper waters, such as ponds, lakes, bays and the ocean – called ‘divers’. When the presa of El Charco fills with ducks, one wonders why it – a small shallow body of water – has been chosen to be the overwintering site of dabblers and divers. It is a blessing. But what evidence is there that there are fish for divers to chase and catch? What evidence is there of waterweed and snails and all the goodies that dabblers eat?
One may take Peterson (A Field Guide to Western Birds, 2nd edn.) and a telescope and learn the markings of each species of duck; but let us look at some general characters that sort ducks into these two groups. As soon as we have done that, we have shortened the list of possibilities by five or six. Then it will be time to note field markings, such as the broad white back of the Canvasback or the long needle tail of the Pintail, easily told in flight.
The way a duck takes off from the water, whether it flies straight up into the air, as dabblers do, or whether it runs along the water surface, getting up speed before becoming airborne, as divers do, is a character trait. It lets us sort the ducks into one or the other of these groups:
DABBLERS
American Widgeon
Blue-winged Teal
Cinnamon Teal
Mexican Duck
Pintail
Shoveler
DIVERS
Canvasback
Lesser Scaup
Redhead
Rind-necked Duck
Ruddy Duck
What if, on our visit, no bird takes to the air, and instead is content to paddle on the water’s tranquil surface and sit in the sunlight. Two things may happen to give us a key. A duck may upend itself, unselfishly assuming a merry posture, hindquarters erect and head under the water: this is a dabbler, without question. If, on the other hand, the whole bird disappears under the water, it is a diver. Once again, we have narrowed the possibilities.
There is still another character: the placement of the legs, whether they occur in the middle of the body or aft. Quite without exception their placement is aft in divers. They need the driving power of the legs to get airborne; whereas the legs of dabblers occur more frequently, but not exclusively, in mid-body. How are we going to see their legs if the ducks are all afloat? We are stuck, because the islands are far away, and the ducks don’t risk appearing on the presa shores - and I didn’t bring my telescope. I checked Audubon’s paintings of the divers. The legs are far back on species he has painted which visit the presa. On the juvenile Ruddy Duck, standing on a rock (Audubon’s ducks are almost all on rocks, politely posed, perfectly still), the legs are farther back than those of its parents or other divers. But Audubon is unreliable on this point, because most of dabbler species that he has painted to be found in El Charco are shown with their legs aft.
There is one last distinction to note. I will have restrained you long enough from looking at the white crown of the American Widgeon or the dark coloration of the Cinnamon Teal. Where are the ducks feeding? This too is a clue. Dabblers will be feeding near shore, where the water is shallow. Islands may be for nesting, but reeds are for feeding; as Wordsworth said, dabblers are found ‘mid the rustling sedge’. And near shore is where we most often see the dabbling Mexican Duck. Whereas the divers take to the deeps with ease.
I have kept the crucial mystery to last. Perhaps you can help. We need an inventory of aquatic life in the presa. When the presa is dry, there is no evidence of fish, aquatic invertebrates, or of aquatic plant life. If you know of anyone qualified to do this kind of study, please let us know. And for now, Good Birding!
Adapted from Wild & Wonderful: Nature Up Close in the Botanical Garden, El Charco del Ingenio, San Miguel de Allende, Guanajuato. Text by Walter L. Meagher; photos by Wayne Colony. 2008.