I’m concerned about the wildlife on the trails. What can I expect to see?

In the Santa Monica Mountains there is a wide variety of wildlife.  You are most likely to see rabbits and deer, which of course pose no threat to humans (assumingly you aren’t interested in becoming a threat to them).  Coyotes and bobcats are also common and are afraid of humans.
There are six or seven known mountain lions in the Santa Monica Mountains.  Despite what you may have heard mountain lions are extremely unlikely to attack humans.  If you see a mountain lion and it does not immediately flee get up on your tiptoes, raise your arms and make yourself tall to scare it away.
Additionally during the warm summer months it is possible for rattlesnakes to be in the vicinity of the trail.  If you see a rattlesnake on the trail stop and wait for it to leave the area.  Do not try to walk or run around it or jump over it.