Oregon Revised Statutes Cities § 221.909

At any meeting of the council a majority of the councillors shall constitute a quorum for the transaction of business. A less number may adjourn from time to time, and may compel the attendance of absent members in such manner and under such penalties as may be prescribed by ordinance. The mayor shall preside at all meetings of the council when present, and in case of the absence of the mayor the council may appoint a mayor pro tempore. In case of the absence of the recorder, the mayor or presiding officer pro tempore shall appoint one of the members of the council recorder pro tempore. The person appointed to act as presiding officer during the absence of the mayor shall not be required to take the oath of office, but the records of the council shall show who is appointed to serve pro tempore at any meeting.