Foxes and coyotes are what happen while I am calling bobcats. I rarely go out just for foxes or coyotes. I am normally going out specifically for bobcats. Foxes also tend to live in similar areas so they have a tendency to show up. I hunt coyotes during the off season, when bobcats are off limits, mainly to stay in practice.
I don't know Iowa, but I know cats. Look for brush. If you have fields that border tree/brushlines, that is where I would call. Give them cover to travel in and make them feel secure. I find that bobcats tend to like higher pitched calls and lower volumes. I leave my big caller at home unless I am calling in high winds. I don't tend to get too many cats with the big caller. Bobcats also like bird calls, so throw some woodpecker calls at them.
The biggest thing is location, location, location. Thick brush, ravines, treelines, rocks all will hold bobcats. If you are not calling towards those features you are going to have a low success rate.
