▁However , ▁it ▁is ▁unlikely ▁that ▁any ▁horses ▁left ▁by ▁the ▁Spanish ▁surv ived , ▁and ▁more ▁likely ▁the ▁current ▁population ▁desc ends ▁from ▁horses ▁brought ▁to ▁the ▁island ▁in ▁the ▁ 1 8 th ▁century ▁by ▁the ▁English . ▁C umber land ▁Island ▁became ▁part ▁of ▁the ▁C umber land ▁Island ▁National ▁Se ash ore ▁in ▁ 1 9 7 2 ▁when ▁the ▁National ▁Park ▁Service ▁( N PS ) ▁took ▁over ▁its ▁management . ▁These ▁horses ▁are ▁similar ▁to ▁the ▁bands ▁of ▁horses ▁living ▁on ▁the ▁islands ▁of ▁Ch inc ote ague ▁and ▁Ass ate ague . ▁There ▁is ▁estimated ▁to ▁be ▁a ▁population ▁of ▁between ▁ 1 5 0 ▁and ▁ 2 0 0 ▁horses ▁on ▁the ▁island . ▁H ors es ▁on ▁C umber land ▁Island ▁have ▁a ▁relatively ▁short ▁life ▁expect ancy , ▁due ▁to ▁p est ▁inf est ations , ▁disease ▁and ▁their ▁rug ged ▁environment . ▁In ▁ 2 0 0 0 ▁a ▁behavior al ▁study ▁found ▁that ▁inst ability ▁marks ▁the ▁bands , ▁with ▁large ▁numbers ▁of ▁co - domin ant ▁st all ions , ▁early ▁dispers al ▁of ▁ju ven iles , ▁and ▁frequent ▁band - ch anging ▁among ▁mar es . ▁ ▁The ▁her d ▁has ▁been ▁studied ▁period ically ▁since ▁the ▁late ▁ 1 9 8 0 s , ▁with ▁research ers ▁recomm ending ▁various ▁management ▁strateg ies ▁depending ▁on ▁the ▁focus ▁of ▁their ▁study . ▁Current ▁her d ▁levels ▁have ▁been ▁shown ▁to ▁have ▁a ▁negative ▁effect ▁on ▁their ▁environment ,