Gas giants put out a fair amount of heat from gravitational collapse, so there's bound to be quite a bit of upward moving winds. If Carl Sagan's idea about aerial ecologies pans out, could larger organisms soar endlessly on thermal updrafts? Are the updrafts outside storms thought to be strong, or like a mild breeze? Got to wondering about this because the mostly H-He atmosphere would make buoyancy-only methods of staying airborne kind of tricky. Small stuff is easy to imagine, but larger stuff may need a boost.