'Egg-Maculate' Conception? Stray rooster, no question whatsoever. You don't have to hear neighbor roosters or even know if any are around, because they migrate. Distant, backwoods farm here. We've had early a.m. migrating roosters show up for decades. Then, off they go. The natural will to reproduce has no limits, even in chickens. I've seen stray roosters, alone in the woods, but never in cold winter with snow. So depends on what time of year this took place.