No bears to speak of. Rattle snakes, yes, but in over 20 years riding these trails I have seen only 5. Cougars, yes, but sightings are very rare and no human contact has been reported. Lots of bob cat, deer and other harmless forest creatures. Ticks in the brush, though not much report of lyme disease.
Big horse flies.
Elk can be seen at Pt Reyes. Cows graze on some park lands. Weather is perfect for riding - usually cool with early morning and late afternoon fog. Dress in layers. Cool mornings, warm afternoons, and late afternoons can get cool again.