This is a list of convicted sex offenders currently within the Davis limits, as per Megan's Law. According to this site, there are 24, with violations ranging from sexual assault to child molestation. Five offenders are in violation of registration requirements.
In California, Megan's Law is made manifest in Section 290 of the CA penal code. A more useful summary is at http://www.sexcriminals.com/megans-law/us/california/.
People with a history of sex crimes are significantly more likely to commit future sex crimes than the general population, but this is a statistical fact, not applicable to every sex offender. However, sex offenders have a lower recidivist rate than other criminals.
MapSexOffenders.com has a list of convicted sex offenders based upon location.
Please note that the code mandates penalties for misuse of this information. Misuse of the database to commit a felony is punishable by five years' imprisonment, and misdemeanors are punishable by a fine of $500 to $1000. These penalties are in addition to the ordinary punishments for the felony or misdemeanor in question.