At about 0645 Mountain time, the airplane impacted terrain and was substantially damaged. The commercial pilot and his passenger received serious injuries. Visual conditions prevailed. The pilot was maneuvering at about 300 feet agl on a wildlife-spotting mission. To lose altitude, the pilot initiated a series of turns and slipped the airplane. Near the end of this sequence, the airplanes descent rate increased and the airplanes left wing contacted terrain.
