Heard they winter in caves, have put Bear traps across every cave entrance I can find, almost back to Spring now, no dice.<snip>
Where did you hear that?
What I know is there is a 2.5 year old NEWS entry, listed in game top level directory, inside the news.txt file, as follows:
Version: 3.60 (beta)
Released: 15-Sep-2019
fixed: bears active and awake in the winter.
Now they hibernate during the winter as they should.
As you can see, it mentions the hibernation but not the location or the detail of hibernation mechanic.
This is speculation but I am guessing hibernation in this game's context probably just means animals are removed from the game world.
In other words, it probably does not mean bears going into caves to hibernate there and eventually walk out at the end of hibernation period.
With this suspected background, what you did is logical in the real world (i.e.: what goes into cave will eventually walk out of cave thus a trap outside it makes sense); in the game world though, probably bears magically spawn on tiles rather than walk out of caves so traps in front of caves have no particularly high chance of trapping one.
<snip>What's a good way to track one down?
Bears are everywhere. Just cover more ground, you will eventually find one. If you go north, east, or northeast you will probably have higher chances of spotting one but you do not
have to go any particular part of map to spot one.
Won't help with your current game but a tip for later: when you are starting a new character, increasing eyesight would help spot more.
More info on eyesight physical stat is on the wiki, here:
https://www.unrealworld.fi/wiki/index.php?title=Eyesight