I feel like the SFHs are quite bold. That is endearing but can also get them into trouble. We had terrible predation issues last year (2014/15) but it was almost exclusively the SFHs we kept losing rather than our other breeds. My husband and I believe it was because the Swedes kept leaving the rest of the flock and going farther and farther from the house. Losses were from hawks and neighbor (far off, not close by, neighbor dogs). They're a great breed, though - best of luck with your situation!
Sorry to hear about your loss of SFH last year. At least I've only lost "regular" chickens so far. If I had lost either of my two SFH, I would have been really upset. They do seem more bold, intelligent, and wild than the other breeds I have. They love to forage, and the hen would much rather lay eggs in the secluded corner of the horse stall than in the elevated nest boxes in the coop.