Pheasants were so thick here when growing up, that many places had contests for the longest tail feather. I understand that there are multiple reasons for the decline of pheasants. Farming practices, pesticides, etc.
Young birds eat mostly insects rather than seeds. So shorter irrigation schedules and spraying cut down on the bugs.
And I used to hunt weed filled ditches, fencelines, etc. Now most fields are cleaned up.
At least the refuges have the pheasant habitat figured out and there is some good wild bird populations to hunt on them.