天美传煤mv视频在线播放_免费完整版片，Thedocumentarydepictsmonarchbutterflies’greatandmysteriousmigration.Eachyear’sautumn,millionsofmonarchbutterfliesstarttheirincrediblesouthwardmigrationfromCanada,crossAmerica,toMexico.Theyflyabove2,000milestoarrivethemountainofMexico.....ThefilmopenswithcaterpillarsmunchingmilkweedinsouthernCanadainlatesummer.Sooneachcaterpillartransformsitselfintoasilkychrysalis.Roughly10dayslater,adelicatefour-wingedmonarchemerges.Then,atsomeunknownsignal,themonarchstaketotheaironatwo-month,2,000-mileflightoverfields,forests,cities,plains,openwater,deserts,andfinallymountainstocongregateinatiny,high-altituderegionofcentralMexicowherethey'veneverbeenbefore.Incredibly,theyarrivebythemillionsatthesametimeeachyear.Sheddinglightonthisnaturalwonderaresomeoftheworld'sleadingmonarchresearchers,includingLincolnBrowerofSweetBriarCollege,independentbiologistBillCalvert,andOrley"Chip"TayloroftheUniversityofKansas.Puttingthemonarchphenomenonintoperspective,Taylorsays,"You'vegotabutterflythat'soriginatinginToronto,orit'soriginatinginDetroit,Michigan,orit'scomingdownfromSt.PaulormaybeevenWinnipeg,andit'smovingsouth.SomehowitfindsitswaytoMexico.Couldyoudothat?"Nooneyetknowshowthebutterfliesdoit,butTaylor'sresearchrevealsthattheyareexpertnavigators.Inoneexperiment,hetransportedMexico-boundmonarchsfromKansastoWashington,DC,andthensetthemloose.Atfirst,theyflewsouthasiftheywerestillinKansas—acoursethatfromWashingtonwouldmissMexicoentirely.Butafterafewdays,theycorrectedtheirflightpath,asifsomeinbornGPSunithadalertedthemtothetruedirectionoftheirdestination.Inanothersequence,NOVAaccompaniescelebratedmonarchwatcherBillCalvertaroundbackcountryTexasashelooksforsignsofthemonarchmigration.Sureenough,theyshowupenmasseandontime,headingtowardtheSierraMadremountainsacrosstheborder—thelastlegoftheirflight.AndintheMexicanstateofMichoacán,NOVAjoinsmountainvillagersastheycelebratethearrivalofthemonarchsinthefirstweekofNovember.Thebutterflies'arrivalmarksthestartofacelebrationcalledtheDayoftheDead,sincethelocalpeoplehavetraditionallyassociatedthemonarchswiththereturningsoulsoftheirdepartedancestors.Unfortunately,illegalloggingintheMexicanbutterflysanctuariesthreatenstheuniquehabitatthatmonarchsdependonfortheirsurvival.Monarchsmaynotyetbeanendangeredspecies,buttheirannualmigrationisanendangeredphenomenonthatcoulddwindletoinsignificanceifthegiantfirsthattheyclingtoduringthewinterdisappear.Gonealsowouldbethecolorfulfestivalthatclosestheprogram—afireworksdisplaywelcomingthehardyflierstoMexico,withorangeburstsagainsttheblacksky,lookingalmostlikethebeautifulcloaksofthemonarchs.. 网友点评：地下生活的片段让人害怕，不禁感叹能活在地表呼吸新鲜空气真好
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