Now just to be clear, these are from the Farmer's Almanac, and they're not exactly a tabloid rag, so these are definitely real.
Pigs Gathering Sticks
Now ordinarily this isn't the sort of thing a pig does, as far as I know. But if you find that your pig, or your neighbor's pig, or whatever pig to which you happen to have access is gathering and hoarding sticks, then now might be the year to treat yourself to that snowmobile. The bigger the pile of sticks, the worse the winter. If the pile of sticks is four feet high and in the middle of a river or stream, it's probably not a pig but a beaver. Don't be fooled, despite their similarities.
Thick Hair on the Nape of a Cow's Neck
Run outside right now and check the neck of your favorite cow. Is the hair you find there just a little bit brushier? A bit more abrasive to the touch? Be sure to check your giant leather-bound logbook from last year: cross reference under "Hair Thickness, Cow, Back Of The Neck" and then sharpen your quill pen. Record this year's thickness: "thyck as a lengf of sailor's ye olde rope"." Compare to last year. Uh oh! Looks like a bad one!
Woodpeckers Sharing A Tree
Woodpeckers are famously non-committal and standoffish creatures, and if they shack up with one another it's only if they're REALLY serious about the relationship. Or if it's going to be a hard winter. As a rule, if you're looking for mild winters, move to where the woodpeckers are profoundly, even cripplingly alone, never leaving the tree except to buy more Mountain Dew and frozen pizzas.
Muskrats Digging Holes High On River Banks
This one is very conditional. If the muskrat digs the hole on a riverbank, it means a bad winter. If the muskrat digs a hole in the pine barrens of New Jersey, it means he's burying a body. If it digs a hole next to a Presbyterian church, it means he's found religion. If it digs the hole and then climbs in and keeps digging, it's running for office.
And naturally, there are regional Montana variants, as well. The most sure-fire sign of the approach of a harshwinter in Montana is that bears sh*t in the woods, and that it is currently a day ending in y.