We don't have fishers where I live, but we do have weasels and mink. I gave some guineas to a friend a few years ago and the first night she had them, a weasel got into the pen and ripped the guineas apart. It didn't eat them, it just destroyed all of them. Only one was left alive and it had one wing completely ripped off. It still makes me feel horrible to think about it! I don't mention it to worry you, only to say if they are anything like weasels or minks, they are the worst predator to have around, as they just seem to kill many at one time just for the fun of it, not for a meal. You probably know all of this, but thought I'd mention it in case others aren't aware of the damage these critters can do!
Luckily, my friend was able to trap and kill the weasel.....I gave her more guineas after that, and they are doing fine. Fortunately, I don't seem to have of these around my house as they seem to live mostly around areas with rivers, ponds, or other large water source.
Well, I think on one hand Fishers are amazing creatures, just like the hawks, coyotes, fox, owls, etc. BUT they aren't so great when it comes to being a predator. Let me stand corrected, they ARE GREAT as predators, that's the problem. We have weasels too, but I haven't seen or had evidence of any - although one of our neighbors mentioned that her cat killed and brought home two of them! Good thing we have cats that terrorize the neighborhood here! I know that weasels just kill for the sheer fun of it. That would be very upsetting to know that guineas you had given your friend were killed on the very first day. That is horrible! Good that she was able to trap it and was willing to try it again with the guineas. It would be a bit traumatic to go through. We've been quiet on the predator front for a long time. Let's hope it continues that way! Thanks for the info.