Guineas are pretty hardy so they should do pretty well over the winter, depending on where you live. I live in SE Iowa. It's fairly cold here and mine do pretty well. They free range during the day and are in a coop at night. I have heated water for winter but rarely provide any other heat souce (unless it's bitterly cold). As for predators, you may lose a few, but hopefully no more than that! I think you will find they help a lot with ticks and other bugs. Mine go through my garden and pick bugs and pests off my plants but don't eat any of my veggies (they love grasshoppers, crickets, and ticks). I really enjoy my Guineas....they aren't the brightest crayons in the box as far as birds go, but they're goofy and a lot of fun!