Pheasants disappeared as farm fields got larger,  fence rows and fences taken out to control weeds.  Probably the best winter food for pheasants were the native bachelor button flower seeds,  hard and durable,  that were available deep into winter.  And then we had the 1964 flood and few pheasants after that.  

Wood ducks were rare,  but as filbert farming grew,  and teasel spread,  Boy Scouts installed thousands of wood duck boxes,  and now they are plentiful.  Probably will fall in population as the old boxes fall apart to age and decay,  and not being replaced.