Complex sentence: Many owners of household parrots have observed their pets using various tools to scratch the back of their necks, including discarded feathers, bottle caps, popsicle sticks, matchsticks, cigarette packets and nuts in their shells.
Split into simpler sentences: Many owners of household parrots have observed their pets using various tools to scratch various parts of their bodies. These tools include discarded feathers, bottle caps, popsicle sticks, matchsticks, cigarette packets and nuts in their shells.