No person shall keep, expose, let loose or suffer to escape any bird or fowl for the purpose of having it shot at for sport, gain, the trial of skill of marksmen or any other purpose, nor shall any person shoot at any bird or fowl that has been kept, exposed, let loose or allowed to escape for the purpose of being shot at. The provisions of this section shall not prohibit the release of legally propagated game birds or the subsequent shooting of such birds during the open season or any extension of such open season.