I'd  say  fox,,  and do  exactly  what  J-dub said,,,.  and  maybe lay  a  branch  on the  ground as to limit the approach  angles ??  and lay  a couple trail sets un-baited and as scent free  as  possible leading  to  the  baited trap,,,,,now  be prepared  to  disspatch  a  yote  thats  been  caught  by  the  hind leg,,, 

,, don't  ask how I know this.    also  maybe  leave  a drop of  curiosity scent on a low  hanging  branch  above  the  set,,,,as  they  get  comfy  flipping  your trap  they'll  step  in to it  while sniffin  what  the heck it  was.   man  I  miss  trapping!!!   JEFFW