▁ 6 5 1 ▁species ▁of ▁terrest rial ▁sn ail ▁are ▁en demic , ▁as ▁are ▁a ▁majority ▁of ▁the ▁island ' s ▁but ter f lies , ▁scar ab ▁be et les , ▁la ce w ings , ▁sp iders ▁and ▁drag on f lies . ▁ ▁Environment al ▁issues ▁ ▁Mad agas car ' s ▁varied ▁fa una ▁and ▁fl ora ▁are ▁end anger ed ▁by ▁human ▁activity . ▁Since ▁the ▁arrival ▁of ▁humans ▁around ▁ 2 , 3 5 0   year s ▁ago , ▁Mad agas car ▁has ▁lost ▁more ▁than ▁ 9 0   percent ▁of ▁its ▁original ▁forest . ▁This ▁forest ▁loss ▁is ▁largely ▁fue led ▁by ▁t avy ▁(" f at "), ▁a ▁traditional ▁slash - and - burn ▁agricult ural ▁practice ▁imported ▁to ▁Mad agas car ▁by ▁the ▁earliest ▁sett lers . ▁Mal ag asy ▁far mers ▁em brace ▁and ▁perpet uate ▁the ▁practice ▁not ▁only ▁for ▁its ▁practical ▁benefits ▁as ▁an ▁agricult ural ▁technique , ▁but ▁for ▁its ▁cultural ▁associations ▁with ▁prosper ity , ▁health ▁and ▁v ener ated ▁ancest ral ▁custom ▁( f om ba ▁mal ag asy ). ▁As ▁human ▁population ▁density ▁rose ▁on ▁the ▁island , ▁def or est ation ▁acceler ated ▁beginning ▁around ▁ 1 , 4 0 0 ▁years ▁ago . ▁By ▁the ▁ 1 6 th ▁century , ▁the ▁central ▁high lands ▁had ▁been ▁largely ▁cleared ▁of ▁their ▁original ▁for ests . ▁More ▁recent ▁contrib utors ▁to ▁the ▁loss ▁of ▁forest ▁cover ▁include ▁the ▁growth ▁in ▁cattle ▁her