It’s difficult to imagine how the two wings could be knocking together to make the sound we hear. Aren’t wings made up of soft, delicate feathers? To explain this, we have to take a much closer look at the Club-winged Manakin’s wing feathers. On two of the feathers, we can see that the hard part, the central shaft or “rachis,” is enlarged towards the end, much like a club. One of these club-shaped feathers has ridges along its edge. The rachis of the next feather is slender, but bent at a 45-degree angle so that it can easily slide over the neighboring ridged rachis. This bent rachis acts as a pick, while its ridged counterpart acts as a comb. The production of sound that occurs when the pick slides over the comb is called stridulation. Stridulation also occurs in insects, such as crickets.