I had excellent luck with trapping a herd of wild sows once (as described here:
http://z3.invisionfree.com/UrW_forum/index.php?showtopic=8130), and in my case, interestingly enough, it appears the successful bait was a captured wild sow from their herd.
I had a trap fence already set up with all pit traps and the sows happened to show up a few tiles away from it, so I chased them toward the fence and ended up trapping one in a pit. The others all took off, leaving their pal behind, and I corralled her on the inside of my trap fence (opposite side from the sow herd) and left. A few hours later, the sows returned and every single one of them ended up stuck in my trap pits, apparently in their efforts to reach the corralled sow. None of the pits were baited as I recall. That was the only time pigs showed up anywhere near one of my traps, so I haven't got any information on trapping them beyond that - I've never bothered making traps specifically for pigs because they're easy enough to hunt down, seeming to tire quickly and have pretty weak senses, as you mention.
If you do happen to trap another wild sow, it might be worth your while to keep her alive in a little fence and place deadfalls or pit traps around the outside in case the others try to come back to her. I suspect this might work with reindeer herds as well if you caught one of the bigger ones that they tend to follow, but I've never had the situation arise myself to test it out. I've tried it with wolf packs (leaving the wolf in the trap, obviously, since fences don't hold them), but that didn't turn out very well for my character. It seems wolves are clever enough not to all blunder into the traps and instead hang around their injured fellow waiting for *you* to come back...