The pilot of a tailwheel equipped airplane reported that, during the takeoff from a grass/dirt runway, the airplane encountered tailwind gusts and had a long ground roll. After the airplane became airborne and cleared the end of the runway, a noticeable degradation of performance was observed. The stall warning horn began to buzz, and the airplane started to descend. While maneuvering the airplane to avoid obstacles, the airplane continued to descend. He performed a forced landing resulting in substantial damage to both wings and fuselage. The pilot reported that there were no preaccident mechanical failures or malfunctions with the airplane that would have precluded normal operation. A weather observation station located about 30 miles south; reported that, about 20 minutes after the accident, the wind was variable at 3 knots, gusting to 25 knots. The airplane was taking off from runway 3.