▁some ▁National ▁Park s . ▁These ▁national ▁par ks ▁include ; ▁Al pine ▁National ▁Park ▁in ▁Victoria , ▁Bar r ington ▁T ops ▁National ▁Park ▁in ▁NS W , ▁and ▁Car nar von ▁National ▁Park ▁in ▁Queensland . ▁Occ asion ally ▁they ▁are ▁must ered ▁and ▁domestic ated ▁for ▁use ▁as ▁camp dra fter s , ▁working ▁stock ▁horses ▁on ▁far ms ▁or ▁stations , ▁but ▁also ▁as ▁trail ▁horses , ▁show ▁horses , ▁P ony ▁Club ▁mount s ▁and ▁pleasure ▁horses . ▁They ▁are ▁the ▁subject ▁of ▁some ▁controvers y ▁– ▁regarded ▁as ▁a ▁p est ▁and ▁threat ▁to ▁native ▁e cos ystem s ▁by ▁environmental ists ▁and ▁the ▁government , ▁but ▁also ▁val ued ▁by ▁others ▁as ▁part ▁of ▁Australia ' s ▁her itage , ▁with ▁supp or ters ▁working ▁to ▁prevent ▁in hum ane ▁treatment ▁or ▁ex termin ation , ▁and ▁re hom ing ▁Br umb ies ▁who ▁have ▁been ▁captured . ▁ ▁There ▁are ▁no ▁known ▁pred ators ▁of ▁fer al ▁horses ▁in ▁Australia , ▁although ▁it ▁is ▁possible ▁that ▁d ingo es ▁or ▁wild ▁dogs ▁occasionally ▁take ▁fo als . ▁On ▁average , ▁ 2 0 % ▁of ▁the ▁fer al ▁horse ▁population ▁dies ▁each ▁year , ▁mainly ▁from ▁dr ought , ▁poison ous ▁plants ▁and ▁par as ites . ▁F ew ▁fer al ▁horses ▁reach ▁ 2 0 ▁years ▁of ▁age . ▁The ▁maximum ▁possible ▁rate ▁that ▁fer al ▁horse ▁numbers ▁can ▁increase ▁is ▁ 2 0 – 2 5 % ▁per ▁year . ▁ ▁History ▁