The pilot reported that while on a cross-country flight over an area of mountainous terrain, he noticed a bear that was near the entrance to a mountain pass. He said that while orbiting over the bear, a strong downdraft emanating from the pass entrance caused the airplane to descend toward the saddle of the mountain pass. The pilot said that he applied full engine power in an attempt to arrest the descent, but the airplane's main landing gear wheels ultimately touched down in an area of grass-covered terrain. The airplane's left main wheel subsequently struck a large rock, and the left wing struck the ground, resulting in substantial damage to the left wing and fuselage. The pilot said that just after the accident, he estimated the surface wind to be from 090 to 140 degrees at 10 knots, with gusts from 15 to 20 knots. The pilot reported no mechanical anomalies that would have precluded normal operations.