for foxes, live bait works really well, around here foxes RARELY go into baited traps, we had to trap on on my dads friends property that was killing his bobwhites, they set up a trap with a culled quail in the back, the fox simply found a way to roll the trap until the door shut and pulled the quail through the flap in the top.
tried that three times, each time the fox would trip the trap and pull the quail through the bait slot (the reason we know it WAS the fox is because my dads friend is a big time hunter and has wild-life cams set up around his quail pens.
so what he did was took some bob-white chicks and put them in a VERY secure metal cage and quadruple zip-tied the door so the fox couldn't work the door open and se the cage with the quail at the back of the live trap and put a backet over the whole thing except the entrance, and that same night, one trapped fox and 4 still safe if not terrified bob white chicks. what they did with the fox afterwards I don't know, i don't want to think about it, bt he did invite us over for dinner the next day...i didn't go LMAO