▁would ▁lead ▁a ▁band ▁together , ▁and ▁alternate ▁bre eding ▁of ▁the ▁band ' s ▁mar es . ▁Fo als ▁born ▁on ▁C umber land ▁Island ▁were ▁less ▁likely ▁to ▁surv ive ▁than ▁compar able ▁fo als ▁in ▁western ▁fer al ▁her ds , ▁with ▁surv ival ▁rates ▁of ▁ 5 8 . 8 - 6 1 . 1 % ▁and ▁ 8 0 % ▁respectively . ▁This ▁was ▁found ▁to ▁be ▁especially ▁true ▁in ▁animals ▁born ▁after ▁ 1 ▁June , ▁which ▁was ▁attributed ▁to ▁higher ▁temper atures , ▁higher ▁insect ▁levels ▁and ▁reduced ▁food ▁avail ability . ▁The ▁number ▁of ▁horses ▁in ▁the ▁C umber land ▁bands ▁was ▁compar able ▁to ▁western ▁bands ▁and ▁those ▁on ▁some ▁eastern ▁islands . ▁However , ▁Ass ate ague ▁and ▁Sh ack le ford ▁B anks ▁horses ▁t ended ▁to ▁have ▁larger ▁bands , ▁with ▁an ▁average ▁of ▁ 8 . 1 ▁and ▁ 1 2 . 3 ▁horses ▁per ▁band , ▁respectively . ▁ ▁Cont ro vers y ▁and ▁management ▁ ▁An ▁initial ▁study ▁published ▁in ▁ 1 9 8 8 ▁by ▁a ▁research er ▁from ▁Oak ▁R idge ▁National ▁Labor atory ▁demonstrated ▁the ▁then - current ▁population ▁of ▁ 1 8 0 ▁horses ▁was ▁over - gra zing ▁the ▁island . ▁The ▁research er ▁recommended ▁reducing ▁the ▁her d ▁size ▁to ▁between ▁ 4 9 ▁and ▁ 7 3 ▁animals , ▁which ▁she ▁cont ended ▁was ▁the ▁maximum ▁size ▁that ▁the ▁island ▁could ▁support ▁without ▁environmental ▁damage . ▁The ▁study ▁showed ▁that ▁the