Cal. Penal Code § 858

When the defendant is brought before the magistrate upon an arrest, either with or without warrant, on a charge of having committed a public offense, the magistrate must immediately inform him of the charge against him, and of his right to the aid of counsel in every stage of the proceedings. If it appears that the defendant may be a minor, the magistrate shall ascertain whether such is the case, and if the magistrate concludes that it is probable that the defendant is a minor, and unless the defendant is a member of the armed forces of the United States and the offense charged is a misdemeanor, he shall immediately either notify the parent or guardian of the minor, by telephone, telegram, or messenger, of the arrest, or appoint counsel to represent the minor.