That's perhaps a small part of it, but there's only an estimated 4-6,000 total in the state and per DFG "...there are indications that mountain lion activity, such as depredation, attacks on people, and predation on prey populations, peaked in 1996, then decreased somewhat, and have remained stable for the past several years."

Decreased deer population is primarily from habitat loss and poaching. We're talking a net reduction of nearly half a million, meaning the gross loss is rather huge.

Originally Posted By rockchucker22
Deer populations have suffered greatly in Ca for a host of reasons including the outlawing of lion hunts.