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发布时间：2023-09-21 16:16:06
VOA慢速英语：猎豹跑得快，但能否赖以生存呢？IsCheetahFastEnoughtoSurvive?ByVOA19October,2021In1900,about100,000cheetahslivedintheworld.Todaythereareonly10,000oftheanimals.Justabouteveryoneknowsthatcheetahsarefast.Somestudieshavemeasuredtheirspeedatabout95kilometersanhouroverdistancesofabout366meters.Soitseemsreasonablethatallthatsprintingwouldrobthewildcheetahofsomeofitsenergy.Itseemsthatallthatexercisewouldmakethebig,spottedcatalikelytargetofattack.Butuntilrecentlynooneeverreallymeasuredhowmuchenergyacheetahusesup.\AcheetahontheplainsofMasaiMaragamereserve,Kenya.JohnWilsontookpartinthecheetahresearch.Hesayscheetahscaneasilydealwiththoseenergyoutbursts."Likeanycat,basically,theyrestformostoftheday.Andtheyhaveonlybriefperiodsofactivity.So,forexample,acheetahwouldonlyhuntinthemorningforafewhours–intheafternoonforafewhours.Weassumetheyexpendalotofenergyduringthesechases.Theyoffsetthosehigh-energyexpendituresbyrestingformostoftheday.Sotheseblisteringspeedsthattheyrunforshortperiodsdonotreallyhaveaneffectonthecheetahsovertheentireday."
Butifthecheetahsarenotoutofbreathorweakafterthechase,whatcausestheirpopulationtodecrease?Someexpertssayotherpredators,likelionsorhyenas,mightbestealingmostofthecheetahs'foodaftertheymakeakill.Dr.Wilsonsaidthenewstudyfoundthatisnotreallywhathappens."Ourstudyhasfoundthatthat'sactuallynotreallythecase.Cheetahsloseabout12percentofthefood.Sowhiletheylosequiteabitoftheirfood,cheetahsareprettyfasteaters.So,they'veeatenalotofthatfoodbeforetheyusethatfood.Theactoflosingfoodisnotthatsignificant."Itappearsthatthecheetahisvulnerabletoattacksbyotheranimalsbecauseofitsphysiology--thewayitsbodyoperates.Thecatsimplyburnsalotofcalories--theenergyproducedbyfood."Becausethesecheetahshaveafastmetabolism–theyhavehugelungsandastrongheart--theirrestingmetabolicrateisreallyhigh.Sojusttheactofwalkingalreadyforacheetahisprettyexpensive.Andthenthelongertheylookforfood,themoreenergytheyneedtoinvestinfindingthefood."And,hesays,thatistheproblem.Ittakesalotlongerforcheetahstofindanimalstheycancatchandeat.Andtheyhavetowalkalotfarthertodoso.Mr.Wilsonsaysthatisbecausetheynaturallyavoidpeople.Buthumanbeingsareincreasinglyoccupyingtheareaswherecheetahstraditionallylookforfood.Housesandfences
正在进行安全检测...
