Oregon Revised Statutes Property Rights and Transactions § 105.620

(a) The person and the predecessors in interest of the person have maintained actual, open, notorious, exclusive, hostile and continuous possession of the property for a period of 10 years;

(b) At the time the person claiming by adverse possession or the person's predecessors in interest, first entered into possession of the property, the person entering into possession had the honest belief that the person was the actual owner of the property and that belief:

(c) The person proves each of the elements set out in this section by clear and convincing evidence.

(2)(a) A person maintains “hostile possession” of property if the possession is under claim of right or with color of title. “Color of title” means the adverse possessor claims under a written conveyance of the property or by operation of law from one claiming under a written conveyance.

(b) Absent additional supporting facts, the grazing of livestock is insufficient to satisfy the requirements of subsection (1)(a) of this section.