Passengerpigeons(旅鸽)onceflewovermuchoftheUnitedStatesinunbelievablenumbers.Writtenaccountsfromthe18thand19thcenturiesdescribedflocks(群)solargethattheydarkenedtheskyforhours.
Itwascalculatedthatwhenitspopulationreacheditshighestpointthereweremorethan3billionpassengerpigeons--anumberequalto24to40percentofthetotalbirdpopulationintheUnitedStatesmakingitperhapsthemostabundantbirdintheworld.Evenaslateas1870whentheirnumbershadalreadybecomesmalleraflockbelievedtobe1milewideand320miles(about515kilometers)longwasseennearCincinnati.
Sadlytheabundanceofpassengerpigeonsmayhavebeentheirundoing.Wherethebirdsweremostabundantpeoplebelievedtherewasanever-lastingsupplyandkilledthembythethousands.Commercialhuntersattractedthemtosmallclearingswithgrainwaiteduntilpigeonshadsettledtofeedthenthrewlargenetsoverthemtakinghundredsatatime.Thebirdswereshippedtolargecitiesandsoldinrestaurants.
Bytheclosingdecadesofthe19thcenturythehardwoodforestswherepassengerpigeonsnestedhadbeendamagedbyAmericans’needforwoodwhichscattered(驱散)theflocksandforcedthebirdstogofarthernorthwherecoldtemperaturesandspringstormscontributedtotheirdecline.Soonthegreatflocksweregonenevertobeseenagain.
In1897thestateofMichiganpassedalawprohibitingthekillingofpassengerpigeonsbutbythennosizableflockshadbeenseeninthestatefor10years.ThelastconfirmedwildpigeonintheUnitedStateswasshotbyaboyinPikeCountyOhioin1900.Foratimeafewbirdssurvivedunderhumancare.ThelastofthemknownaffectionatelyasMarthadiedattheCincinnatiZoologicalGardenonSeptember11914.
1.Inthe18thandearly19thcenturiespassengerpigeons________.
A.werethelargestbirdpopulationintheUs
B.livedmainlyinthesouthofAmerica
C.didgreatharmtothenaturalenvironment
D.werethebiggestbirdintheworld
2.Theunderlinedword“undoing”probablyreferstothepigeons’________.
A.escapeB.liberation
C.ruinD.evolution
3.Whatwasthemainreasonforpeopletokillpassengerpigeons?
A.Toseekp
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