I had a spayed cat that used to run away from May to October. He did it for five years or so, until our other cat went missing (probably eaten by a fox..). He always came back well-fed, but with a lot of scrapes and shit, and we strongly suspect he spent the summers fighting with (non-existant) bears over the territory.. One year our neighbours called and asked us to get him, since he had stopped at their horse farm for a few days on his way home and beat their stable cats and ate their food... He also just sat and stared down a charging border collie once! The sucker some how lived 'til 19!