Whenever I try to describe wadging, I end up making it sound too clinical: Chimpanzees wadge in order to extract nutrients from fibrous foods. This is true in the sense that humans eat food in order to extract nutrients, but but it doesn’t get at the enjoyment that we feel when we eat.
I’m pretty sure that chimps get that same feeling when they wadge. One of the most mysterious aspects of it (to me anyway, maybe there’s a good explanation) is that they seem compelled to keep checking on the wadge. They hold it out on the tip of their lips for a visual inspection. They take it out and hold in their hand. They work on rolling it into the perfect ball. I don’t know what makes a wadge good or bad from a chimp’s perspective, but it seems like they are constantly evaluating them.
Young’s Hill is too dry for growing cattails, but we collect them from a nearby pond and give them to the chimps. Cattails are great for wadging, as Burrito demonstrates here: