The chickens have now tasted freedom and use the pen move to their advantage.  The design modifications we made to the Salatin portable pen has a disadvantage when it comes to escaping chickens.  However, there is a door built in on the side and it is relatively easy to herd them all back into the pen after the move (especially with new food put down).  The chickens tend to stay close to the pen and don’t venture off the plot area that was planted to grass and clover (and now contains all manners of weeds).  As they get older I’m sure they’ll get braver and venture off into other areas of the garden.