Gone Forever a Contemporary Look at the Extinction of the Passenger

POPULATION ECOLOGY

Gone forever Passenger Pigeon (Ectopistes migratorius)HREEHUNDRED wasYEARS the AGO, world'sTHE mostabundant land bird. Althoughfound only in easternNorth America, it num- beredthree to five billion,accounting for about a quarter of all North American landbirds. Passenger Pigeons traveled in flocks of hundredsof millions, at times obscuringthe sun. More than a century haspassed since the lastgigantic nesting colonies,and over seventyyears since the deathof the last PassengerPigeon, Martha,in the CincinnatiZoo. Although therehas been much speculationabout the extinctionof the PassengerPigeon sincethat time, mostof the proposedex- planationsare inadequate. The PassengerPigeon was never seri- ouslystudied while it still existedand the publishedaccounts are incompleteand oftencontradictory. Most of ourinforma- tion comesfrom reportsin the scientific and popular literature of the late nine- teenthand early twentiethcenturies. Lit- tle hasbeen written about the Passenger Pigeon'srole asan importantcomponent of the easterndeciduous forest ecosys- tem. Its reproductivebehavior exploited the mastfruiting of thesetrees, which in Photo/TheBell Museumof Natural History. turnsupported the tremendousPassenger Pigeonpopulations. One of the keys to the bird's successlay in its ability to nu- mericallyoverwhelm its predators. The precipitousdecline of the Passen- A contemporary look ger Pigeonfrom 1871 to 1880, and the birds' subsequentextinction, was an in- escapabledemographic consequence of at the extinction the relentlessdisruption of the nesting colonies,which resulted in repeatednest- ing failures.This was facilitatedby the developmentof the easternrailroad network andthe telegraph,which madeev- of the Passenger Pigeon ery colonyaccessible to marketharvest- ing. Overhuntingdid not exterminatethe PassengerPigeon, as is commonlybe- lieved, rather, over two decades,cohorts died withoutthe opportunityto replace themselves. Was overhunting the causeof the Passenger Pigeon'sdemise or was the bird an early victim of technology? tinctionNORDER of TO theUNDERSTAND Passenger Pigeon, THEEX-its ecologyand incredibleabundance must first be considered. Nomadism and colonial behavior were critical to the Passen- David E. Blockstein and Harrison B. Tordoff ger Pigeon'ssuccess. The birdsnested in coloniescontaining millions of pairs,

Volume 39, Number 5 845 traveledtogether to feed, and roostedto- autumnremained on the ground Because getherat night. During springmigration thelocations of largemast crops changed andthe breeding season, the entirepopu- fromyear to year, PassengePigeons rare- lation consistedof an amazingly small ly nestedin the sameplace in two con- numberof groups,probably fewer thana secutiveyears. After certainpoor mast dozen.These groups were stupendous, years,there was probably no majornest- oftenfilling the sky and taking days to ing attempt.In most years, at leastone passover an area. The descriptionsof enormouscolony nested in the east(usu- •these flights--"indescribable multi- ally in the forestsof New York or Penn- tudes,""so thick that they obscurethe sylvania)and one in the midwest.During light"--would be unbelievablewere they the 1800s, the midwestcolony usually not repeatedby so many authors.The nestedin Michigan,where it fed onbeech largestflight ever recorded was estimated mast, and in alternateyears, in Wiscon- to contain2,230,270,000 birds (Wilson sin, where the birds fed on acorns 1832). By travelingand nestingin such A nestingusually consisted of several

Beech leaves and mast largegroups each pigeon was essentially coloniesin adjacentcounties. The largest shieldedfrom predators,a concept nestingever recordedcarefully, in W•s- known as predatorsatiation. Wherever consinin 1871, covered850 squaremiles the pigeonswent there were not enough andcomprised at least135 millionadults local predatorsto seriouslydetract from (Schorger1937). Every suitable tree had their numbers. nests,sometimes fifty or more, eachcon- How could so many pigeons find tainingonly one egg. Nestingwithin a enoughfood? Before settlement by Euro- colony was highly synchronous,w•th peans,eastern North America was almost mostof the eggslaid on the sameday completelycovered by deciduousforest. Therewere so many nests that nonhuman Severalof the forest trees--beech, oaks, predatorscould hardly affect nesting suc- and chestnut--producedlarge nutritious cess. nuts that were the main food of the Pas- Certain aspects of their biology, sengerPigeons. Every few yearsin any sharedwith otherdoves and pigeons (Co- given area, these trees producedenor- lumbiformes),allowed Pasenger Pigeons mouscrops of nuts.This patternof "mast to form thesegigantic nesting colomes fruiting" at unpredictabletimes enabled Their tremendousmobility, granivorous x....-•..•_.• the treesto satiatetheir local seedpreda- diet, andthe productionof pigeonmilk* Oakieaves and mast tors--as colonial behavior enabled the in the cropsof breedingadults, allowed pigeonsto satiatetheir predators--and the birdsto providetheir nestlingsw•th thusincrease their reproductivesuccess. food gatheredfar from the nestingcolo- Flocksof PassengerPigeons roamed the ny. Like othercolumbids, the parentsex- forest, often flying hundredsof miles a changednest-tending duties twice dally, day, untilthey found an areawith a heavy with the male on the nest for about s•x mast crop. They remained there until hoursat middayand the femaleon for the they depletedthe food supply. So effi- remainder of the time. This allowed each ciently did they scour the forests that parenttime to travel far enoughto get hogssometimes starved in their wake. In foodfor itself and its nestling.The d•ff•- summer,when nuts weren't ayailable, culty of providingenough food for two the PassengerPigeons wandered to the nestlingsand pressuresto keepthe nest- northern Great Lakes states and Canada ing periodas shortas possiblemay have to feed on a wide varietyof berries.Be- beenfactors working to limit the clutch causethe pigeons dispersed after nesting, size to a single egg. the summer and fall flocks were smaller The nestingseason usually began m in comparisonwith the springflights, but April andconcluded in May or June Th•s still huge. In late fall and winter the onlyallowed time for one or two nestings flocks continued their nomadic wander- a year, but thereis no evidencethat any ing throughthe southernUnited States, individualattempted a secondbrood after where acorns were the main food. Here a successfulnesting. It is known that the pigeonsformed tremendousroosts, pairsreplaced clutches, especially those Chestnut leaves and mast oftenbreaking limbs and destroying trees destroyedby late snowstorms.The nest- by theircollective weight. Someof these ing seasonseems to havebeen controlled PassengerPigeons often disgorgedthe con- fall and winter roosts were at traditional tentsof their cropsin order to consumea more by the availabilityof nuts; the supply favoredfood. Theypreferred beechmast over sites,occupied whenever there was a suf- acorns, and buckwheat more than wheat. Au- ficientfood supply. * a curd-likesubstance produced by both sexes at hatch- ingtime to feed the young. Though it containsno sugar, dubon estimated that 1,115.136,000 birds Nestingcolonies formed in the spring it resemblesmammalian milk in thatit consistsof salts, consumed8,712,000 bushelsof mast daily. where large cropsof nuts from the past fats and proteins,

846 American Birds, Winter 1985 .\

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Volrune39, Nmnber5 847 diminishedrapidly each spring as a result themand enjoy their shareof the spoil." subjectof gmat speculation:unknown of germinationand consumption not only diseases,"loss of vigor," mass drown- by pigeons,but alsoby insects,microor- Y ALL ACCOUNTS,THE FINALDE- ings, emigration to South America or ganisms,mammals, and other birds. Al- cline of the PassengerPigeon was Australia. Yet, at the time, some orni- thoughPassenger Pigeons ate a varietyof rapid. It is impossibleto know whether thologistsunderstood quite well "that all fruits and seeds,the mastcrops were es- populationlevels in the mid-! 800s were other theories... to account for the de- sentialfor nesting. comparablewith those under primitive structionof the birdsby othercauses than The localimpact of a PassengerPigeon conditions. Pigeon numbers declined man'sagency are absolutelyinadequate" flock was devastating.Schultz (in Mc- first in the East, perhapsas early as the (Forbush 1913). The most obvious hu- Kinley 1960)describes a roostingarea in late eighteenthcentury (Schorger 1955), man impact on pigeonswas the direct Missouriwhere a forty acrearea "had the then in the Midwest. Several writers have killingof adultsand young. This wasac- appearanceof having sufferedfrom a suggestedthat this was owing to defores- companiedby habitatdestruction through hurricaneor tornado." A great deal of tation for humanagriculture. deforestationthat might, in time, have timberwas destroyedat theseroost sites. There were still hundreds of millions beenfatal to the species.However, nei- Dung accumulatedbeneath the roost of PassengerPigeons left in the early ther overharvestingnor habitat destruc- trees to a thickness of several inches or 1870s, when they were still regardedas tion by themselvesare sufficientcauses more,killing the vegetation,although ul- pests by Michigan farmers (Barrows for the extinction of the Passenger timately enrichingthe soil. Passenger (1912:246). The 1870s was a decadeof Pigeon. Pigeonsmay have been important disper- catastrophicdecline but the nestingpopu- Although deforestationprobably af- salagents of foresttrees, transporting un- lationin 1878 was still conservativelyes- fectedthe PassengerPigeons' decline in digestedseeds in theircrops (Webb ms.). timatedat 50 million (Fischer 1913). The theEast, adequate forest areas still exist- The effects of a flock of Passenger PassengerPigeon becamescarce in the ed at the same time the bird was becom- Pigeonson the local fauna was equally 1880s and was very rare in the 1890s. ing scarce.In the major nestingarea of impressive.Nut-eating animals such as The lastreliable specimens were of single north-centralPennsylvania, deforesta- squirrels, chipmunks, and Blue Jays individuals collected in Wisconsin in tion beganin 1872 but did not reachfull facedsevere local competition from Pas- September1899 (Schorger 1938) and speeduntil 1892 (French 1919:110). De- sengerPigeons. Raptors and mammalian Ohio in March 1900 (Henniger 1902). forestation came even later to Ontario predatorstook full advantageof a pigeon The last authenticsight recordhas been (Mitchell 1911). Michigan was still well colony. In referenceto a roost in Ken- muchdebated. A two year rewardcam- woodedin 1883, althoughbeing logged tucky, Audubon(1831:323) wrote, "The paign, sponsoredby the AmericanOrni- rapidly (Rand McNally and Co. 1883). howlingsof the wolvesnow reachedour thologists'Union from 1910-1911to de- Logging was initially concentratedon ears, and the foxes, lynxes, cougars, termine whether the PassengerPigeon pines,which were muchless important to bears,raccoons, opossums, and pole-cats was extinct, failed to discoverany con- PassengerPigeons than deciduoustrees. wereseen sneaking off, whilsteagles and vincingevidence of its existence(Hodge The PassengerPigeon was exterminat- hawksof differentspecies, accompanied 1911, 1912). ed becausepigeon harvestingactivities by a crowdof vultures,came to supplant The causes of extinction have been the by humansprevented recruitment to the

TAKINg.,THE: BIBDS FROMTHE TRAP-NET 8,. J•ACIN• THEN.

Methodsof co!!ectingpigeons varied: young were knocked from nestswith long poles; nesting trees were cut down or seton fire; birdswere suffocated by burningsulphur under nesting trees; netting and the useof "stoolpigeons" were most commonly used. The Bertmann Archive.

848 American Birds, Winter 1985 population;entire cohortsdied without replacing themselves. Forbush (1913) stateda similaropinion: "The destruction of mostof the youngbirds for a seriesof yearswould bring aboutsuch a diminu- tion of the speciesas occurredsoon after 1878." How did this happen?

T ;•rAl•)•OFalwaysFLOCKS meantOFPASSEN- food to the local people,whether natives or set- tlers. Nevertheless,people probably had little impact on the number of pigeons untilthey began harvesting them for market insteadof for the homeonly. Market harvestingbegan before 1800, but was not a major industryuntil 1840. Two technologicaldevelopments of the 19thcentury increased the efficiency and scopeof market harvestingto the pointwhere it was ultimatelyresponsible for the extinction of the Passenger Pigeon. The seemingly unrelated ad- vances were those of the railroad and the telegraph. Kno•cnfor its maneuverabilttvand speedand grace in flight, the PassengerPigeon's well- In 1830, there were only 23 miles of deservednickname •t'as the "blue meteor." Photo/TheBell Museumof Natural History. railroad track in the United States (Rand days. Freightmoved almostas fast, tak- After 1861, only a handfulof colonies McNally and Co. 1883). By the time of ing, in 1849, nine transfersand ninedays were too far from rail or ship for market the Civil War, there were over 30,000 to go from Philadelphiato Chicago. By exploitation. In 1881, even a nesting miles of track and a railroad network 1859this took three days without transfer colonyin Oklahomathat was I l0 miles throughmost of America eastof the Mis- {Chandler 1977). from the nearestrailroad was plundered sissippiRiver was complete{Chandler The telegraphserved to keep the pro- by professionalswho used teams and 1965).This networkallowed the profes- fessionalpigeoners informed of the lo- wagonsto haul out their quarry. sional pigeoners,who numberedabout cationsof nesting colonies. The entire The impactof the harvestwas stagger- 1000in their heyday, rapid accessto all operationwas efficiently, although infor- ing. At the 1860 nestingnear Grand Rap- major nestingcolonies. Equally impor- mally, organizedso that word of any ids, Michigan, pigeonersshipped 588 tant, it provideda quick way to shipbar- nestingof pigeonsspread rapidly for hun- barrels•over 100,000 pounds-•of pi- relsof pigeonsto the big city marketsin dredsof miles. The railroad companies geonsto market.At 350 pigeonsper bar- the east and midwest. In 1800, travel be- benefittedfrom the pigeon harvest and rel, more than 200,000 pigeonswent to tween New York and Chicago took six transport,so they undoubtedlyhelped in distant markets from that nest site. In- weeks. By 1830, it took only three seeingthat this informationwas transmit- cluding local markets and home use, weeks,and by 1857 it tookless than two ted. birds that died in the nest, and birds left

Thedevelopment of a nationwiderailway system made #possible to get the birdsquickly to market.Five thou.•andbarrels were shipped from a single nesting(30 dozenbird.• to the Ixtrrel), at a costper barrelof $6 to $12 The telegraphI•ept hunters #tformed of nestinglocations.

Volume 39, Number 5 849 Instead, PassengerPigeons became extinct becauseover a periodof about20 years--twice an individual's lifetime --adults were preventedfrom replacing themselves,directly by the nestlinghar- vest and indirectly by the shooting, which led to nest abandonment. Had re- productioncontinued, it is unlikely that nettersand shootersaway from the nesting sites could have exterminated the PassengerPigeons. There were simply too manypigeons for the harvestof adults to be complete. The first record of a nestingcolony being abandonedbecause of shooting was in 1869 in Wisconsin Laws passed in the early 1880s to prohibit shooting near the colonies were ineffective; abandonment by adult birds became even more common. Slaughterat the nestingcolonies continuedto the end. The lastknown attempt at colonialnesting was in 1887, in Wis- consin. These birds left about two weeks after they startedto nest, probablydis- turbedby shooting. What happenedonce the PassengerPi- geonpopulation was reducedto a small number of old birds'? Was extinction in- Aneurl_v environmentul lampoon from tilelute 19th century. Protest.* aguinst tile muss sluughter of evitable, or could the populationhave PussengerPigeons begun as eurlyas 1875. mostlyagainst trup shooting. Laws were pussed in the eurlv 1880sprohibiting shooting at the ne.,tingsites. but they were ineffectiveThe Bettmann persistedat low levels?Halliday (1980) Archive. and others have argued that the social |•cilitation of a large colonywas neces- saryfor the PassengerPigeons to breed, for the hogs to clean up, probably as have wiped ou! the speciesbecause the so that once the populationfell below a manyas one million birdswere destroyed restof the pigeonsin the colony contin- criticalsize there was no attempt at repro- at this single nesting. Harvests of this ued to nest, apparently undisturbedby duction. However, it is well documented magnitude continued for another 20 the netting activities. that some PassengerPigeons, albeit a years!The larges!harvest was probably Althoughmarket harvestersprobably small number, nestedsolitarily and in at Petosky,Michigan, in 1878, wherethe accountedfor most of the mortalily, ev- smallgroups even whenthe specieswas nestingcolony covered nearly 250 square ery nestingcolony was invadedby shot- superabundant.Some pairs bred success- miles. In three months, 1.5 million dead gunners,many of whom were locals,but fully in captivity (Deane 1881, 1896). and more than 80,000 live birds were also included well-heeled sportsmen The pigeons continuedto attempt to shippedby rail, andprobably as many by from distant cities, whose harrassment of breed even after the populationwas re- water. Up to 10 million pigeons may thenesting birds was intense.People shot ducedto low levels. Some reproductive haveperished at that nestingalone. birdswithin the nestingcolony, even at successoccurred; many of the last speci- the nest. The commotion probably menstaken were youngbirds. Nest suc- caused individuals and even whole colo- cessin theselast small coloniesand by nies to abandon their nests. lhe lone pairs must have been pitifully The fat nestlings were prized even low. Without the numericalprotection more than the adults. Professionals and providedby the large colonies,the birds localsalike used every conceivable meth- were unable to satiate the local pred- y captureHREEMAINPassenger METHODS Pigeons: WEREUSEDnetting TO od to harvest the nestlings---chopping ators. These last birds were doomed as adults, shootingadults, and taking the downthe nesttrees, knockingthe young theyattempted solitary nesting, building youngfrom the nest. out of the nestwith poles,and even set- unconcealednests, and layingonly a sin- Most professionalharvesters captured ting the nest trees on tire to causethe gle white egg. This very low rate of re- adults in nets at baited sites near the nest- adultsand young to jump out. In a typical productionwas just not enoughto save ing grounds.A singlerelease of the net denselypopulated colony it was possible the species,whose whole reproductive oftentook more than 100 birds. Although to harvestnearly all the young. strategydepended on massnesting. And this techniquewas usedsince the 1600s Despite the scale of the slaughter, so, the PassengerPigeon, which was or earlier and millions of pigeonswere overhuntingdid not exterminatethe Pas- once the most abundant land bird on the killed this way, nettingalone could not sengerPigeon, as it nearlyhad the bison. planet, vanishedforever.

850 American Birds. Winter 1985 ACKNOWLEDGMENTS

We greatly appreciatethe effort of A.W. Schorgerwho spenthundreds of hours accumulatinginformation about PassengerPigeons and thank the Depart- mentof Wildlife Ecologyof the Univer- sity of Wisconsinfor allowingus to ex- amine Schorger's notebooks. Billy Goodmanprovided editorial assistance in the preparationof this manuscript.

LITERATURE CITED

AUDUBON, J.J. 183I. OrnithologicalBi- ography,Vol, I. Edinburgh. BARROWS, W.B. 1912. Michigan Bird Life. Michigan Agric. College, Lan- sing,Michigan. 822 pp. CHANDLER, A.D., JR. 1905. The Rail- roads.The Nation'sFirst Big Business. Harcourt, Brace and World, Inc. New York. __. 1977, The Visible Hand. Harvard Univ. Press.Cambridge, Mass. DEANE, R. 1881. Breedingof the wild pigeonin confinement.Bull. Nuttall Orn. Club 6: 60. __. 1896. Somenotes on the Passenger Pigeonin confinement,Auk 13: 234- 237. FISCHER, M. 1913. A vanished race. Bird-Lore 15: 77-84. FRENCH, J.C. 1919. The PassengerPi- Thenest and egg of thePassenger Pigeon. Onee the number of birdswas reduced to a fen; tts uneamoufiagednests and solitary white egg jeopardized its survival. Photo/The Bell Museum of geon in Pennsylvania,its remarkable Natural History.. history,habits, and extinction, with in- terestingside lights on thefolk andfor- MITCHELL, M.H. 1935. The Passenger estlore of theAlleghanian region of the Pigeonin Ontario.Contrib. Royal On- old KeystoneState. Altoona, Pa. 257 tario Museumo.f ZoologyNo. 7.181 pp. PP- RAND McNALLY AND CO. 1883. In- FORBUSH, E.H. 1913.The lastPassenger dexedAtlas of the World. Chicago. Pigcon.Bird-Lore 15: 99-103. SCHORGER, A.W. 1937. The greatWis- HALLIDAY, T.R. 1980. The extinction of consin PassengcrPigeon ncsting of the PassengerPigeon, Ectopistes migra- 1871. Proc. Linnaean Soc. o.f N.K 48: torius, and its relevanceto contempo- 1-26. rary conservation.Biol. Conserv. 17: 1938. The last PassengerPigeon 157-162. killed in Wisconsin. Auk 55: 531-532. HENNIGER, W.F. 1902. A preliminary __. 1955.The PassengerPigeon, Its Nat- list of the birds of middle southern Ohio. ural Historyand Extinction.Univ. of Wilson Bull. 9: 77-93. Wisconsin Press, Madison and Univer- HODGE, C.F. 191I. The PassengerPigeon sityof OklahomaPress, Norman (paper- investigation.Auk 28: 49-53. back}. __. 1912. A last word on the Passenger WEBB, S,L. Did the PassengerPigeon Pigeon.Auk 29: 169-175. (Ectopistesmigratorius) disperse seeds? --Department of Ecology and McKINLEY, D. 1960. A historyof the Unpub. ms. Behavioral Biology, Bell Museum PassengerPigeon in Missouri.Auk 77: WILSON, A. 1832. American Ornithol- of Natural History, Universi.tv 399-420. ogy.Vol. 5, Philadelphia,Pa. of Minnesota,Minneapolis. MN 55455.

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