The pilot of the tailwheel equipped airplane reported that he was contracted for an aerial survey to spot bears. After spotting bears, he flew multiple low altitude passes to maintain sight of the bears. While maneuvering uphill at a low altitude, his attention was "drawn into the visual of the bear and cubs" and away from the terrain. When he regained focus, he decided to turn the airplane to the right, away from rising terrain, but about 90º into the turn, the airplane descended, impacted the terrain, and a post-crash fire ensued. The airplane sustained substantial damage to the wings and fuselage. The pilot reported that there were no preaccident mechanical failures or malfunctions with the airplane that would have precluded normal operation. The pilot added that he should have let the observer examine the bears during the low passes.