That is a long tailed weasel in winter coat , they turn that coloer in the northern cold states. Summer they are brown with a lighter under belly. The long tailed weasel has a black tip on their tail winter or summer.
There are three kinds of weasel present in North America, Least, Long Tail, and Short Tail.
Their ranges overlap and in some parts of North America all three are present.
The Least weasel is the smallest living carnivore, they are rarely seen and seldom trapped.
Description A tiny weasel. Brown above, white below. Tail very short, brown. Feet white. All white in winter in North. L 6 3/4-8 1/8" (172-206 mm); T 7/8-1 1/4" (24-38 mm); HF 3/4-7/8" (19-23 mm); Wt 1 1/4-1 3/4 oz (37-50 g).
Found this thread and wanted to comment. A simple rat trap with bloody raw meat tied to the trigger with floss will take care of them or a set up like a weasel box. Look up a local Trapper, he will be glad to help you out.
This weasel incident happened to a friend of mine who lives in the Upper Peninsula area of Michigan. He fixed it last spring and has reported no more losses. They used to free-range their geese and chickens. Some 4 years back, they left for around 2 hrs and returned to find all of their geese and chickens slaughtered. Dogs were suspected, best I can recall. Don't know if they ever decided to keep them in a run like I do or are taking their chances. But they had to start all over again because they lost every single bird.
If we ever let ours free range, half of them would be on the porch begging for treats all day long and crapping all over the porch and the lawn furniture.
And soon enough the resident red-tailed hawks would begin to thin out our flock.
So I keep mine in a nice 1900 sq ft run with netting over the top. No predators have gotten into our run or coop yet, and to date, we have never had any parasites or diseases in our flock.