This isn't new and may have been mentioned before but the DFG site has two pdf files showing pheasant harvest on the wildlife areas over a period of time. They have some nice line graphs that really says it all. Here's the link to the page. Go down to the publications list. Have a couple of stiff drinks before you open them.
http://www.dfg.ca.gov/wildlife/hunting/uplandgame/
http://www.dfg.ca.gov/wildlife/hunting/uplandgame/