Before I started bird watching I don’t think I realized just how many variety of ducks there are in North America. I am not talking about waterfowl in general, but specifically ducks. I think when you say duck, most people think of two things, the Mallard, with his green head and yellow bill or they think of the yellow rubber ducky in their bathtub. But there are well over a hundred varieties of ducks in the world, thirty-one common enough to be listed in my Eastern North America guide. Over the next several posts I would like to take a closer look at these different species and what makes them each unique.
Before we can examine their differences, we need to establish just what qualifies waterfowl as a duck? There are four main behaviors and four major physical features that define a duck. To be classified as a duck, the species must tick all eight boxes.
The behaviors that define a duck include how it breeds, eats, flies, and quacks. Unlike other varieties of birds, ducks often breed across different varieties, creating hybrid ducklings sometimes with both wild and domestic parentage. This is perhaps not that difficult to believe. Many duck varieties will join together in one large flock, especially in winter. It seems they are drawn to each other by their similarities.
With regards to feeding, ducks usually eat one of two ways, they are either diving ducks or dabbling ducks. Dabbling is when a duck tips itself upside down in the water, with its back side still visible on the surface. Diving ducks behave similar to cormorants, penguins and other water birds, completely submerging in search of nourishment.
When it comes to flying, ducks are the original inventors of vertical take-off. While other waterfowl require space for a runway, ducks can usually take off almost vertically, regardless of whether they are on land or in the water. Unlike geese and other waterfowl, you will rarely see a duck glide unless it is landing. Instead notice the quick and regular flapping of their wings, which is how they keep themselves in the air.
As anyone who has ever heard a wooden duck call will know, most ducks don’t really “quack, quack” outside of nursery rhymes and children’s books. What is different about their communication is that among duck species, it is the female rather than the male that makes most of the noise. The males do get louder during mating season, but the rest of the year it is the females who dominate the conversation.
The physical characteristics that define a duck include its body type, bill, feet and plumage. All ducks have an oval body, although the extent of how oval does vary between types. Along with being oval, duck bodies also tend to be compact, which helps them to retain heat and aids swimming. Another characteristic common among ducks is the location of their legs, often located towards their tail. While this placement plays a role in creating their awkward waddle on land, it provides more power when in the water.
Aside from their placement on a duck’s body, the feet of a duck are themselves a defining feature. Wide and heavily webbed, a duck’s feet are two important tools for swimming and diving. Despite the webbing, usually three distinct “toes” or bone structures can be distinguished. These toes often terminate with nails or talons.
While duck bills do vary greatly among species, often being different colors, size and shape, a flat, broad bill is common to all. The bill, differs from a beak in that it can function as a strainer and ladle, a helpful feature for birds that feed on aquatic vegetation. Bills often have lamellae on the sides. Sometimes mistaken for teeth, these comb-like structures help filter the water, similar to the way whales have baleen to help them filter water from their mouths when they feed. For a good look at lamellae, I recommend you check out http://www.thenaturalistsnotebook.com/our-blog/tag/lamellae
Plumage is key to distinguishing a duck. Both its structure and color help separate it from the plumage of other species. Like most birds, duck feathers have two distinct layers or types, contour and down feathers. Because of the amount of time a duck spends in the water, its contour or flight feathers are tightly hooked to ensure that even when fully submerged, the downy layer does not get wet, in turn insuring that the duck will remain warm, even in the winter. (For more details on feather structure you can refer to my Feathers post https://tailsofatwitcher.com/2020/03/25/feathers/ ). With most duck varieties, the males and females have different coloring. The females are usually muted and plain when compared to the plumage of their male companions. The females’ coloring often provides for better camouflage, which the male’s bright feathers serve a different, but very important purpose: attracting a mate. However, many people don’t realize that once mating season is over, the male ducks of many varieties molt, replacing their distinctly colored feathers with more muted plumage that allows them to better resemble the females.
Now that we have a better understanding of similarities shared by all duck varieties, we will be better able to compare their differences in future posts. For the next several weeks, I will be focusing on different duck varieties that I have seen in the wild and detailing what makes them unique.