▁first ▁homes ▁in ▁the ▁South ▁Island , ▁where ▁their ▁spread ▁was ▁helped ▁by ▁gu ards ▁dro pping ▁them ▁off ▁at ▁country ▁railway ▁stations . ▁H edge h ogs ▁were ▁introduced ▁to ▁the ▁North ▁Island ▁about ▁ 1 9 0 6 ▁and , ▁from ▁then ▁on , ▁their ▁numbers ▁increased ▁at ▁an ▁exponential ▁rate . ▁By ▁the ▁ 1 9 2 0 s ▁they ▁had ▁become ▁so ▁numerous ▁that ▁game - bird ▁hun ters ▁bl amed ▁them ▁for ▁reduced ▁bag - s izes . ▁H edge h ogs ▁were ▁declared ▁no x ious ▁animals ▁and ▁a ▁b ount y ▁of ▁one ▁sh illing ▁a ▁sn out ▁paid ▁by ▁regional ▁authorities ▁for ▁several ▁years . ▁By ▁the ▁ 1 9 5 0 s , ▁h edge h ogs ▁could ▁be ▁found ▁over ▁the ▁whole ▁country ▁with ▁the ▁exception ▁of ▁the ▁col dest ▁wet test ▁corner ▁of ▁the ▁South ▁Island ▁and ▁al pine ▁areas ▁of ▁permanent ▁snow . ▁Nevertheless , ▁h edge h ogs ▁have ▁been ▁seen ▁clim bing ▁New ▁Zealand ▁gla ci ers . ▁H edge h ogs ▁do ▁not ▁reach ▁the ▁same ▁weight ▁in ▁New ▁Zealand ▁as ▁in ▁col der ▁parts ▁of ▁Europe . ▁With ▁its ▁mil der ▁winter s , ▁New ▁Zealand ▁h edge h ogs ▁hibernate ▁for ▁only ▁three ▁months ▁of ▁the ▁year ▁so ▁do ▁not ▁need ▁to ▁put ▁on ▁so ▁much ▁weight ▁in ▁aut umn ▁as ▁their ▁ancest ors . ▁ ▁In ▁northern ▁New ▁Zealand , ▁many ▁h edge h ogs ▁do ▁not ▁hibernate ▁at ▁all . ▁One ▁of ▁New ▁Zealand