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Many ways to be a duck

123rf.comNorthern shovelers have an over-sized spatulate bill with a set of horny plates that help filter out the edibles sucked into its mouth.

If it walks like a duck and quacks like a duck, it must be a duck. But be careful. There are a great many ducks, and not all quack. Each has its own special way of making a living.

To scan a pond with a half dozen species paddling around, they may appear to all be doing pretty much the same thing. Not so. Watch carefully when it comes time to feed. There are floaters and sinkers, more often referred to as dabblers and divers.

I still remember the 12-year-old boy I encountered on the shore of Tillamook Bay years ago who had a battered pair of binoculars and no field guide. He had come up with his own names for birds and referred to scoters as “black sink ducks.” I didn’t ask what he called the dabblers, those that do not dive for a meal. I wonder what he is doing now. With his curiosity and determination, I’m betting he is a noted ornithologist today.

Among dabblers, there are skimmers (cinnamon teal), mud-suckers (mallards), and pickers (gadwall). Many dabblers prefer to tip up and feed off the bottom (northern pintail). Some dabblers frequently leave the pond and march around in herds, grazing (American wigeon).

Different divers prefer different depths and whether they are among the emergent vegetation (ruddy ducks) or in open water (canvasback). Mergansers prefer fish and crayfish. There are many ways to be a duck.

One of my favorites is the northern shoveler. They are one of the most specialized feeders among ducks. They are supreme skimmers and have an over-sized spatulate bill as the name suggests. The bill itself has a set of horny plates that are attached to the upper mandible that help filter out the edibles sucked into the mouth. Their tongue is even more specialized, with a fringe of fine fleshy projections that further help filter out small food items — much like the baleen of whales.

Most often they just paddle around and filter the surface water where duckweed and small invertebrates congregate. They rapidly suck in mouthfuls of water and then press out the water through the plates and fringe of the tongue, swallowing the bounty.

If you are patient, you may see small groups of shovelers gathered at a productive patch swimming in a tight circle. These pinwheels of ducks look a bit strange, but it is an effective cooperative foraging strategy. As they paddle in a circle, they apparently create a minor current that brings more food to the surface, where it is collected. Individual phalaropes, a small swimming shorebird, spin on the surface of the ocean creating a current that draws food to the surface.

The foraging strategy is quite successful, and there are different shoveler species with large spatulate bills found on lakes and ponds around the world. The northern shoveler found in the Rogue Valley occurs across Europe and Asia, as well as North America.

Cinnamon and blue-winged teal are “apprentice” filter-feeding skimmers. Both have enlarged spatulate bills although not as grand as that of the shoveler. Neither teal displays the pinwheel behavior. While ducks, may waddle and quack, a duck is not just a duck.

Stewart Janes is a retired biology professor at Southern Oregon University. He can be reached at janes@sou.edu.