Not too far from where I live there's this one busy road with these little man-made rock ponds where a bunch of mallards like to settle. Well, today, when passing these ponds, I noticed two big white ducks in there with them; definitely not the wild critters I was used to seeing. I pulled over to check them out and found that they were both hens, one that I think's a Pekin cross with an interesting mix-match black bill and orange feet, and the other white with cream colored patches. They showed no obvious signs of illness and even though the weather's been really cold lately (so cold most of their pond was iced over), they seemed pretty robust, at least robust enough to harass the poor little mallards. I don't really have any room to house these gals for the long run, but I can't just leave them out there like that either. What should I do?