The owner, lessee or other person entitled to possession of unenclosed lands may have erected and maintained signs or placards legibly printed, easily discernible, conspicuously posted and reasonably spaced or, alternatively, may mark the posted land as set forth in section one, article three-b, chapter sixty-one of this code, so as to indicate the territory in which hunting, trapping or fishing is prohibited.

Any person who enters upon the unenclosed lands of another which have been lawfully posted, for the purpose of hunting, trapping or fishing, shall be guilty of a misdemeanor.  The officers charged with the enforcement of the provisions of this chapter shall have the duty to enforce the provisions of this section if requested to do so by such owner, lessee, person or agent, but not otherwise.