ats ▁allowed ▁to ▁ro am ▁out do ors . ▁ ▁In vas ive ▁species ▁▁ ▁Human ▁influ ences , ▁such ▁as ▁colon ization ▁and ▁agricult ure , ▁have ▁caused ▁species ▁to ▁become ▁distributed ▁outside ▁of ▁their ▁native ▁ranges . ▁Fragment ation ▁also ▁has ▁cas c ading ▁effects ▁on ▁native ▁species , ▁beyond ▁reducing ▁habitat ▁and ▁resource ▁avail ability ; ▁it ▁leaves ▁areas ▁vulner able ▁to ▁non - native ▁invas ions . ▁In vas ive ▁species ▁can ▁out - comp ete ▁or ▁directly ▁pre y ▁upon ▁native ▁species , ▁as ▁well ▁as ▁alter ▁the ▁habitat ▁so ▁that ▁native ▁species ▁can ▁no ▁longer ▁surv ive . ▁ ▁In ▁ext inct ▁animal ▁species ▁for ▁which ▁the ▁cause ▁of ▁ext inction ▁is ▁known , ▁over ▁ 5 0 % ▁were ▁affected ▁by ▁invas ive ▁species . ▁For ▁ 2 0 % ▁of ▁ext inct ▁animal ▁species , ▁invas ive ▁species ▁are ▁the ▁only ▁c ited ▁cause ▁of ▁ext inction . ▁In vas ive ▁species ▁are ▁the ▁second - most ▁important ▁cause ▁of ▁ext inction ▁for ▁m amm als . ▁ ▁Global ▁patterns ▁▁ ▁Trop ical ▁regions ▁are ▁the ▁most ▁heavily ▁impact ed ▁by ▁def a un ation . ▁These ▁regions , ▁which ▁include ▁the ▁Brazil ian ▁Amazon , ▁the ▁Congo ▁Bas in ▁of ▁Central ▁Africa , ▁and ▁Indones ia , ▁experience ▁the ▁greatest ▁rates ▁of ▁over exp lo itation ▁and ▁habitat ▁de grad ation . ▁However , ▁specific ▁causes ▁are ▁varied , ▁and ▁areas ▁with ▁one ▁end anger ed ▁group ▁( such ▁as ▁birds ) ▁do ▁not