▁state ' s ▁sugar c ane ▁and ▁rice ▁fields . ▁By ▁ 1 9 6 0 , ▁the ▁Louisiana ▁Department ▁of ▁Wild life ▁and ▁Fish eries ▁estimated ▁the ▁nut ria ▁population ▁along ▁coast al ▁regions ▁to ▁exceed ▁ 2 0 ▁million . ▁The ▁U . S . ▁Department ▁of ▁the ▁Inter ior ▁estimates ▁that ▁ ▁of ▁Louisiana ' s ▁coast al ▁wet lands ▁are ▁occupied ▁by ▁nut ria . ▁ ▁Conserv ation ▁After ▁the ▁first ▁Ar ctic ▁expedition , ▁he ▁noticed ▁on ▁returning ▁to ▁A very ▁Island , ▁a ▁great ▁decl ine ▁in ▁the ▁number ▁of ▁e gre ts . ▁This ▁led ▁him ▁to ▁conduct ▁experiments ▁in ▁capt ive ▁bre eding . ▁Mc Il hen ny ▁founded ▁the ▁Bird ▁City ▁wild f ow l ▁refuge ▁on ▁A very ▁Island ▁around ▁ 1 8 9 5 , ▁which ▁helped ▁to ▁save ▁the ▁snow y ▁eg ret ▁from ▁ext inction . ▁In ▁ 1 9 1 0 , ▁Mc Il hen ny ▁and ▁Charles ▁Will is ▁Ward ▁bought ▁ ▁of ▁mar sh land ▁and ▁later ▁an ▁additional ▁; ▁on ▁November ▁ 4 , ▁ 1 9 1 1 , ▁they ▁dedicated ▁the ▁mar sh ▁to ▁the ▁state ▁of ▁Louisiana ▁as ▁a ▁wild life ▁refuge . ▁Mc Il hen ny ▁persu aded ▁Mrs ▁Russell ▁S age ▁to ▁purchase ▁ ▁of ▁Marsh ▁Island ▁on ▁July ▁ 2 2 , ▁ 1 9 1 2 , ▁and ▁the ▁Rock ef eller ▁Foundation ▁to ▁ac quire ▁an ▁additional ▁ ▁nearby . ▁This ▁created ▁a ▁bird ▁reserve ▁of ▁about ▁.