0   km ▁during ▁October ▁ 1 9 8 8 , ▁using ▁air ▁curr ents ▁in ▁the ▁Inter - T rop ical ▁Con ver gence ▁Zone . ▁ ▁In ▁some ▁mig rat ory ▁but ter f lies , ▁such ▁as ▁the ▁monarch ▁but ter fly ▁and ▁the ▁painted ▁lady , ▁no ▁individual ▁comple tes ▁the ▁whole ▁migration . ▁Instead ▁the ▁but ter f lies ▁mate ▁and ▁reproduce ▁on ▁the ▁journey , ▁and ▁success ive ▁gener ations ▁travel ▁the ▁next ▁stage ▁of ▁the ▁migration . ▁ ▁In ▁m amm als ▁ ▁Some ▁m amm als ▁exhib it ▁extraordinary ▁migr ations , ▁with ▁car ib ou ▁having ▁one ▁of ▁the ▁longest ▁known ▁terrest rial ▁migr ations ▁on ▁the ▁planet , ▁reaching ▁as ▁much ▁as ▁ 4 8 6 8   km / year ▁in ▁North ▁America . ▁However , ▁over ▁the ▁course ▁of ▁a ▁year , ▁gray ▁wol ves ▁move ▁the ▁most . ▁One ▁gray ▁w olf , ▁in ▁particular , ▁covered ▁a ▁total ▁cum ulative ▁annual ▁distance ▁( TC AD ) ▁of ▁ 7 2 4 7   km . ▁ ▁Mass ▁migration ▁occurs ▁in ▁m amm als ▁such ▁as ▁the ▁Ser en get i ▁' gre at ▁migration ', ▁an ▁annual ▁circular ▁pattern ▁of ▁movement ▁with ▁some ▁ 1 . 7 ▁million ▁w ilde be est ▁and ▁hundreds ▁of ▁thousands ▁of ▁other ▁large ▁game ▁animals ▁including ▁gaz elles ▁and ▁z eb ra . ▁A ▁literature ▁survey ▁in ▁ 2 0 0 9 ▁found ▁more ▁than ▁ 2 0 ▁species ▁which ▁eng age ,