Moth

We walked outside our apartment and saw a HUGE bug walking up our front fence. There were birds going crazy all around it. It crawled to the top of the fence and found a plant to rest on. It stayed there for hours. It was an enormous moth that must have emerged from it's cocoon shortly before we spotted it on the fence. We watched it's wings grow larger and larger. It was still on the plant before we went to sleep and was gone this morning. I'm not sure what kind of moth it was, but I'm researching to find out!