South Dakota in the late 60's had a a few very bad winters with the snow very deep, many birds perished in that snow and very cold temperatures, plus some of the early sprngs were very wet and hen pheasants will only try to nest twice before giving up.
Was well aware of that. My group had hunted there every year since 1955.
I've hunted there, and yes Ed I did get of Translyvania, in the late 80's, near Mitchell. Hunted a small 10 section farm and saw hundreds of pheasants in 2 days of hunting in this spot.
I hunted 25 miles SW of Mitchell for 12 years.
Oh, I almost forgot, your state back then was lower than Pa
Still is. Projected harvests are 150,000 vs 200,000.