Yeah, PM me too if you want a deep college level paper. I did my senior thesis on that very subject for my BS in Biology. I've got lots of refrences. Of course that would be a little dated now since I graduated in '90. But there's a lot of studies on that, from population levels, plant impact (over browsing), even deer psychology (over crowding is stressful on deer on lots of levels) Lots of studies show that prey species are dependant on predators for a healthy herd and since we've eliminated most predators (except coyotes and wild dogs) in most areas a lot of prey species have been negatively impacted.

Contact your local game biologist, and organizations like this: http://unendangeredspecies.com/