by Skip Via
skip@westvalleynaturalists.org

West Valley is home for a huge variety of migratory and resident ducks and other waterfowl. While some waterfowl are waders (e.g., sandhill cranes, great blue herons, dowitchers) or skimmers (none around here, although some gulls do this occasionally), ducks can be broadly separated into two groups based on how they obtain food: dabblers and divers.

What’s the difference? Dabbling ducks float along the surface of the water and, displaying a behavior known to serious ornithologists as “duck butt,” dip their heads underwater and their tail feathers up in the air to feed. Divers, on the other hand, ride low in the water and dive beneath the surface to feed. While some ducks forage in more than one way as conditions and food sources dictate, most are predominantly either dabblers or divers. Feeding behavior is sometimes useful in identifying duck species from afar. If it dives, you know it’s not a mallard.

Ducks aren’t the only waterfowl that dabble or dive. Swans and geese are dabblers, while grebes and coots are divers. But that’s for another story. This is about ducks.

Even when ducks aren’t dabbling or diving, you can make a pretty safe prediction about how a duck feeds by observing it swimming or walking. Dabblers float high in the water, and their legs are in the middle of their body. Divers ride low at the water’s surface, and their legs are toward their tails, acting as propellers to push them through the water.

You can also tell if a duck is a dabbler or diver by watching it take off from the water’s surface. Dabblers can take off quickly, usually not needing to run along the surface at all to get airborne. Divers, however, need to run along the surface while flapping their wings in order to take off. Their narrower wings that help them move more easily underwater make taking off more difficult. So comparing wing size relative to body size is another way to tell if the duck you are watching is a dabbler or a diver.

One duck that we see around here–the ring-necked duck–is a less-specialized feeder. It’s basically a diver, but it also dabbles when necessary. Its diet is more varied than most ducks, including both plants and aquatic worms and other invertebrates. Canvasbacks, being omnivores, will also sometimes be seen dabbling. There is an exception to every rule.

One other note about dabblers and divers—having different feeding behaviors allows more ducks to share the same pond without competing with each other for the same food source. Nature always seems to get it right.

Here are some divers and dabblers commonly seen here (photos and videos by Skip Via):

First, some local divers…

And now some dabblers:

And now for some dabbling and diving behavior: