What is the speculum on waterfowl?

The speculum on waterfowl is defined as a bright-colored patch located on the secondaries of the bird’s wing. This distinct color, which often varies among different species, serves several purposes. It plays a crucial role in species identification, as the color and pattern can help differentiate between various species of ducks and other waterfowl during flight. Additionally, the vibrant speculum is thought to be important in mate attraction, as it can signal health and vitality to potential partners.

While nesting areas, types of wing feathers, and feeding behaviors are all significant aspects of waterfowl ecology and management, they do not specifically refer to the characteristic feature that the term "speculum" denotes. The speculum is particularly prominent when the bird is in flight and can be a valuable visual cue in understanding the biology and behavior of these animals.