Passenger Pigeons darken skies

Passenger pigeons once covered area skies, reportedly taking hours for a flock to pass. Birds often placed so much weight on branches they snapped. With the coming of agriculture the birds were a nuisance and were shot, trapped and poisoned.

     "...And now arose a roar, compared with which all previous noises ever heard, are but lullabies, and which caused more than one of the expectant and excited party to drop their guns, and seek shelter behind and beneath the nearest trees. The sound was condensed terror. Imagine a thousand threshing machines running under full headway, accompanied by as many steamboats, groaning off steam, with an equal quota of railroad trains passing through covered bridges -- imagine these massed into a single flock, and you possibly have a faint conception of the terrific roar following the monstrous black cloud of pigeons as they passed in rapid flight in the gray light of morning, a few feet before our faces..."
     So wrote a reporter for the Fond du Lac Commonwealth in describing passing of a flock of passenger pigeons near Wisconsin Dells in 187.
     Similar flocks must have been seen at one time or another during spring and fall migrations moving up and down the Chippewa River valley. At one time in the early 1800s the passenger pigeon was probably the most abundant species of bird on the face of the earth.
     Yet, incredibly, by 1914, less than a century later, it had passed in to oblivion to accompany the dodo and the great auk.
     One wonders what factors contributed to its passing. Was it lacking of food? Was it disease? Was it overshooting?
     We are ahead of our story. Let us first examine overall biology of the species.
     The late A. W. Schorger, Ph.D., did extensive research on the passenger pigeon and wrote the book, "The Passenger Pigeon," in 1937, published by University of Wisconsin Press. Much of the material on this bird is from his book.
     Description - The passenger pigeon was a large (17"), streamlined bird with bluish upper parts and a rusty throat and breast.
     Occasionally, today's hopeful bird watchers think they have spotted a living passenger pigeon. However, they probably have confused it with a mourning dove, a common wild pigeon occurring in the Eau Claire region. The mourning dove is much shorter (12") and is distinguished further by its brown-gray upper parts.
     Although the passenger pigeon is extinct, anyone who wishes to see what it looked like can do so by visiting the Bird Museum at Phillips Science Hall, University of Wisconsin-Eau Claire. The museum contains two fine specimens collected and mounted by J. N. Clark, a turn-of-the-century farmer-ornithologist who lived at Meridian, a few miles from Eau Claire.
     Feeding habits - Nesting passenger pigeons in Wisconsin depended to a large degree on acorns of the hills oak (Quercus ellipsodialis) and black oak (Quercus velutina).
     Both of these species are fairly common in the Eau Claire region.
     Distribution of the nestings, in space and time, of course, was correlated with abundance of acorn cops. Intervals between crop abundance in a given region may vary from three to about five years.
     As a result, passenger pigeons may have nested in a given region one year and then have been absent for several years until the acorn crop was sufficiently large to sustain adults and young through the nesting season.
     It must be remembered that acorns, of course, mature in autumn. The pigeons, on the other hand, nested in spring. This means the acorns were not actually eaten by nesting birds until about six months after they had ripened.
     In the meantime, many of the acorns may have become parasitized by larvae of the acorn weevil (Balaninus.) Such infested acorns were worthless to the pigeons.
     In addition to acorns, Wisconsin passenger pigeons also fed on beechnuts and on seeds of hemlock, pine, juniper, elm, maple, alder and hackberry.

Considered a pest and shot

     Many a Wisconsin farmer considered passenger pigeons pests and shot them on site.
     This is understandable when one learns these birds consumed a great variety of cultivated grains, buckwheat as well as wheat, barley, rye and corn. The birds also ate peas.
     One farmer who shot pigeons in his barley field complained they "pluck it up by the roots and devour it."
     Corn was frequently used to bait pigeon traps. In 1869 over 500 bushels of corn were used in this way at Monroe to bait a single trap for one year.
     Pigeons were not completely vegetarians, however. For example, during insect outbreaks (grasshoppers), they would change their dietary patterns to include some of this fare.
     Roosts - During a typical autumn or winter day passenger pigeons would range widely for food and become quite scattered in the process. However, once feeding activity for the day had ended, many thousands might converge at sunset on a favored roost site in some woods or swamp, possibly 50 to 75 miles from the scene of their foraging.
     Famous American ornithologist John James Audubon describes a pigeon roost he found in Kentucky:
     "...I arrived there nearly two hours before sunset. Few pigeons were then to be seen...The dung lay several inches deep, covering the roosting place like a bed of snow.
     "Many trees two feet in diameter, I observed, were broken off at no great distance from the ground; and the branches of many of the largest and tallest had given away, as if the forest had been swept by a tornado.
     "Everything proved to me that the number of birds resorting to this part of the forest must be immense beyond conception... The sun was lost to our view...Suddenly there burst forth a general cry of "Here they come!" The noise which they made, though yet distant, reminded me of a hard gale at sea, passing through the rigging of a close-reefed vessel.
     "As the birds arrived and passed over me, I felt a current of air that surprised me...The Pigeons, arriving by the thousands, alighted everywhere, one above another, until solid masses as large as hogsheads were formed on the branches all around. Here and there the perches gave way under the weight with a crash, and, falling to the ground, destroyed hundreds of the birds beneath, forcing down the dense groups with which every stick was loaded. It was a scene of uproar and confusion..."
     Nesting - The largest passenger pigeon nesting ever recorded on the North American continent took place within one hour's pigeon flight of Eau Claire in 1871.
     The nesting area was in the shape of the letter L.
     Prof. Schorger states the "long arm, having an average width of six miles, extended from Black River Falls to Wisconsin Dells, a distance of 75 miles. The short arm extended from Wisconsin Dells towards Wisconsin Rapids for a distance of 50 miles and had an average width of eight miles."
     This was, of course, an enormous area embracing something like 850 square miles. Many observers reported a nesting density in some spots of more than 100 nests per tree. A large hemlock in Michigan once had 317 nests. This single Wisconsin nesting probably numbered at least 136 million birds.
     Passenger pigeons laid only one egg per set. The reproductive potential of this species was therefore limited. Even that single egg was sometimes "lost" by the female.
     Harassment by hunters or unseasonably cold weather sometimes caused females to drop their eggs before the nest was ready for them. For example, in 1878 a number of pigeons nesting on islands in Lake Pepin were so persecuted by hunters they dropped their eggs on the ground.
     Numbers - Passenger pigeon flocks that swept through the Chippewa Valley centuries ago like vast "biological storms" must have numbered thousands and possibly millions of birds. The first real attempt to estimate accurately the numbers of birds in such flocks was made by Alexander Wilson early in the 19th century.
     He had been hiking through the Kentucky River valley near Frankfort when he came upon the largest flock he had ever seen.
     He reported:
     "...Coming to an opening by the side of a creek...where I had a more uninterrupted view, I was astonished...They were flying with great rapidity, at a height beyond gunshot, in several strata deep, and so close together that could shot have reached them, one discharge could not have failed of bringing down several individuals.
     "From right to left as far as the eye could reach, the breadth of this vast procession extended...Curious to determine how long this would continue, I took out my watch...It was then half past one...About four o'clock in the afternoon I crossed the Kentucky River, at the town of Frankfort, at which time the living torrent above my head seemed as numerous and extensive as ever."
     At one time the passenger pigeon was probably the most abundant species of bird on the earth. In fact, that single flock of Wilson's contained "10 times as many" individuals as are represented by all 65 or more species of waterfowl on the North American continent today.
     Dr. Schorger says the passenger pigeon at one time numbered up to three billion birds. If this estimate is correct, it would mean at that time this single species accounted for from 25 to 40 percent of all birds living in the United States.
     Persecution - Yet in less than one century the passenger pigeon became extinct. Certainly one of the factors which depleted its numbers in the 19th century was the organized persecution waged by market hunters.
     The Fond du Lac Commonwealth describes a shooting episode at Wisconsin Dells during the great nesting of 1871:
     An immense flock suddenly swept toward the hunters, filling the air with an awesome sound. "...So sudden and unexpected was the shock that nearly the entire flock passed before a shot was fired. The unearthly roar continued, and flock after flock, in almost endless line succeeded each other, nearly on a level with the muzzle of our guns, the contents of a score of double barrels was poured into their dense midst. Hundreds, yes, thousands, dropped into the open fields below.
     "Not infrequently a hunter would discharge his piece and load and fire a third and fourth time into the same flock. The slaughter was terrible beyond any description.
     "Our guns became so hot from the rapid discharges we were afraid to load them. Then while waiting for them to cool, lying on the damp leaves, we used pistols, while others threw clubs, seldom, if ever, failing to bring down some of the passing flock.
     "When the flying host had ceased, scarcely and hour had passed. Below, the scene was truly pitiable. Not less than 2,500 birds covered the ground. Many were only wounded, a wing broken or something of the kind. These were quickly caught and their necks broken..."
     Extinction factors: Now we are in a better position to ask the question posed at the beginning.
     What caused extinction of the passenger pigeon? There apparently was not just one cause; there were multiple.
     First, a large number of potential nest and food trees (oak, beech, etc.) were logged off or burned in order to make room for settlements, farms and roads.
     Second, it is possible infectious diseases took a heavy toll. Certainly pigeons were highly vulnerable to disease epidemics caused by protozoans or bacterian, especially during the colonial nesting period when birds were almost crowded "feather to feather."
     Third, many birds may have been destroyed by severe storms during the long migration between wintering ground in South American and breeding range on the North American continent. Storms may have been more destructive of immature birds than of adults.
     Fourth, inability of the female bird to lay more than a single egg per set may have been a contributing factor to the bird's extinction. Most other species of birds have a much higher biotic potential. Thus, ducks, quail and pheasants may lay eight to more than a dozen eggs per set.
     Fifth, once flocks were reduced to scattered remnants in the 1890s, birds may have lost the social stimulus (both visual and auditory) required for proper completion of mating and nesting activities.
     Sixth, the bird's decline was hastened by persecution by hunters. Every conceivable method of destruction was employed, including guns, dynamite, clubs, nets, fire and traps. More than 1,300 densely massed birds were taken in just a single throw of a net.
     Pigeons were burned and smoked out of nest trees. Not only adults were hunted, but also squabs. They were considered especially tasty.
     Maitland Edey writes:
     "Squabbing was a revolting business. The quickest and most efficient method of collecting a couple hundred squabs in a tree was to chop down the tree....Or you could set a tree afire.
     "A birch would go up in a sudden roar of flames, sending a cascade of half-roasted nestlings to the ground, while the adult birds would go rocketing out of the tree, feathers smoking, to fall singed and helpless miles away..."

Reduced to a single bird

     As a result of a combination of these factors, population of the passenger pigeon, which once numbered over three billion birds, was reduced to a single bird in less than a century.
     The lone survivor, whose immediate ancestors nested in Wisconsin, died in the Cincinnati Zoo Sept. 1, 1914. The Wisconsin Society for Ornithology erected an appropriate monument at Wyalusing State Park to commemorate the pigeon. It was unveiled May 11, 1947.
     Professor Aldo Leopols of the Wildlife Management Department, University of Wisconsin, and an ecologist keenly sensitive to environmental disruption caused by human "progress: delivered the eulogy:
     "...We have erected a monument to commemorate the funeral of a species. It symbolizes our sorrow. We grieve because no living man will see again the onrushing phalanx of victorious birds, sweeping a path for spring across the March skies, chasing the defeated winter from all the woods and prairies of Wisconsin. Men still live who, in their youth, were shaken by a living wind. But a decade hence only the oldest oaks will remember, and at long last only the hills will know..."
     When the attendant at the Cincinnati Zoo discovered the lifeless body of that last passenger pigeon on the floor of his cage, he promptly froze the bird in a 300-pound cake of ice and shipped it to the Smithsonian Institution in Washington, D.C. The bird was then carefully stuffed and mounted.
     It is now on display in an attractive case. Perhaps a visitor would like to see it sometime. However, on a second thought, maybe he would only be disappointed. The handsome feathers still glisten. But, after all, the thunder is gone.

--Ollie Owen, UW-EC, Dept. of Biology

Extracted from the Eau Claire Leader Telegram
Special Publication, Our Story 'The Chippewa Valley and Beyond', published 1976
Used with permission.