AIR TAXI ATTEMPTING TURN AROUND FROM PASS WHEN WX DETERIORATES; HIT TREES.

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WHILE ENRTE FROM JUNEAU TO GUSTAVUS WHERE I HAD STARTED FROM ON THE PREVIOUS FLT; I WAS FLYING AT 1500 MSL ABOVE SCUD LAYER. VISIBILITY WAS 3-5 MI IN RAIN. I WAS ATTEMPTING TO FLY THROUGH FUNTER PASS WHICH I THOUGHT LOOKED GOOD. AS I STARTED INTO THE PASS I BEGAN TO LOSE FORWARD VISIBILITY; SO I BEGAN A DSNDING L HAND TURN BACK TOWARDS THE BEACH TO GO TRY A DIFFERENT RTE. AS I WAS TURNING I SAW A COUPLE EAGLES FLYING CLOSE TO MY INTENDED FLT PATH. I SHALLOWED UP MY TURN SO AS TO AVOID THE BIRDS. I THEN FLEW INTO A PATCH OF FOG; WHICH DIDN'T CONCERN ME MUCH AT THE TIME BECAUSE I THOUGHT I WAS GOING IN A SAFE DIRECTION. BUT BECAUSE I SHALLOWED MY TURN AND THE WIND WAS BLOWING ME TOWARDS A LOW HILL (HILL WAS OBSCURED IN FOG) I ALL OF A SUDDEN HAD TREES IN FRONT OF THE PLANE. I PULLED UP; BUT STRUCK TREE TOP WITH L WING. I THEN LOST SIGHT OF THE GND AGAIN. I COULD SEE FROM THE ATTITUDE INDICATOR THAT ACFT WAS ROLLING RAPIDLY L DUE TO BADLY DAMAGED WING. (IT PUSHED LEADING EDGE TO SPAR IN ABOUT A 2 FT SECTION AND BENT SPAR SLIGHTLY). I THEN CAME OUT IN THE OPEN AND DECLARED AN EMER TO JUNEAU TWR AND LANDED WITHOUT INCIDENT. I FEEL ACCIDENT COULD HAVE BEEN AVOIDED IF I HAD TURNED AROUND SOONER; STUCK TO A MORE FAMILIAR RTE; STAYED LOWER; SO AS NOT TO LOSE GND REF; HAD NOT LET EAGLES DISTRACT ME FROM GREATER DANGER.