Ok.. So my thinking has shifted a bit and I'm holding off on a full yard fence due to HVAC issues. Since the ducks are on order, I have 4 weeks [or so. was open on the delivery date] before they get here. I've shifted to doing a movable, 32" high 2x4 rail/ rough swan poplar slat fence with 2" wide slats. QUESTION.. What is the MAX width between slat that would be recommended to keep adults in. I'm thinking 4" wide and they should not be able to squish through.. Besides, I'll be lining the bottom 6" with chicken wire or some type of plastic fencing. Thoughts?