▁part ▁of ▁the ▁municipality ▁of ▁H erd la ▁until ▁ 1 ▁January ▁ 1 9 6 4 ▁when ▁it ▁was ▁merged ▁into ▁Ask ø y . ▁The ▁island ▁has ▁a ▁nature ▁reserve ▁with ▁ 2 2 0 ▁registered ▁species ▁of ▁birds . ▁During ▁the ▁Second ▁World ▁War , ▁it ▁was ▁the ▁site ▁of ▁H erd la ▁Airport ▁and ▁some ▁coast al ▁fort ifications . ▁ ▁H erd la ▁Church ▁is ▁located ▁on ▁the ▁island . ▁ ▁Air ▁base ▁and ▁coast al ▁fort ifications ▁▁ ▁During ▁the ▁Second ▁World ▁War , ▁all ▁of ▁H erd la ▁was ▁in ▁effect ▁a ▁military ▁base ▁for ▁the ▁German ▁Luft wa ffe . ▁ ▁The ▁flat ▁area ▁" H erd le val en " ▁was ▁considered ▁a ▁good ▁place ▁for ▁an ▁air port . ▁The ▁air ▁base ▁at ▁H erd la ▁was ▁important ▁to ▁defend ▁the ▁west ▁coast ▁of ▁Norway ▁against ▁Al lied ▁attacks . ▁Many ▁fort ifications ▁were ▁built ▁to ▁h inder ▁possibly ▁inv ading ▁forces . ▁ ▁All ▁civ ili ans ▁had ▁to ▁leave ▁the ▁island . ▁In ▁ 1 9 4 5 , ▁they ▁came ▁back ▁to ▁an ▁island ▁full ▁of ▁military ▁install ations . ▁ ▁H erd la ▁was ▁seriously ▁considered ▁as ▁the ▁site ▁for ▁Ber gen ' s ▁main ▁air port . ▁After ▁the ▁war ▁the ▁air ▁traffic ▁control ▁for ▁the ▁Ber gen ▁area ▁was ▁placed ▁at ▁H erd la . ▁However , ▁in ▁ 1 9 5 5 , ▁the ▁air port ▁was ▁finally ▁built ▁at ▁F les land ▁instead , ▁since