If this cat is big, as in fat, then he likely isn't living off the land, he's living out of cat dishes. Not a typical feral profile or behavior.

Except for the fact that I know at least two of my neighbors feed the neighborhood strays, I might feed it. I would, however, be leery of a stray cat because of the possible Feline AIDS and Feline leukemia problems. Are yours indoor cats? Even if yours have been immunized, you still need to be careful. Be sure you wash your hands between handing this outdoor cat and his stuff and your housecats. If yours are outdoor cats then they've probably already exchanged germs.

Both of my cats were strays before our mutual decision to adopt each other. Now they stay in the house. Neither one was remotely "feral," but both were apparently young, lost, and wandering around our neighborhood.

SRS