What was that thing I saw?

At about 40 minutes into the film, immediately after Jimmy Chin says, "They say the best Alpinists are the ones with the worst memory," it cuts to a shot of a round object hanging from a tree. It looks like it's made of twigs or grasses. Does anyone know what that is? Is it a man-made object? Something made by birds? Grasses and twigs that were tangled by the wind? I've seen these before, but I was never sure what they were.