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| Passenger Pigeon, Ectopistes migratorius |
Once upon a time, close to
40 percent of the birds on the North American continent were Passenger pigeons. Their massive flocks would block out the sun for hours. Their flapping wings would create a chill far below. Their flight would create a roar of thunder. Within only decades their numbers decreased from billions to none.
Passenger pigeons had been found from far south Texas up through Canada, encompassed the Midwest all the way to the east coast. Their migration route traced along the Ohio River, and their greatest nesting density was within New England and along the Great Lakes. Their massive nesting sites, the largest recorded taking up to
850 square miles, often destroyed trees and coated the forest floor with inches upon inches of waste. So many pigeons could be found in some sites that there were birds sitting upon birds. The grounds nearby looked swept as the twigs and branches were gathered for nests. Within the nest laid either
one or two eggs, a number still debated as evidence during the time were simple accounts from various sources.
Passenger pigeons fed on a variety of plants, but their preference was for hard mast such as
beechnuts and acorns. The young were fed
pigeon milk, the sloughed off lining of the crop. The pigeons themselves fed a number of species including black bears, bobcats, owls, hawks, wolves, and skunks. Passenger pigeons also fed many Native American groups, some relying on them far more than others.
The understanding of the role and connection the Passenger pigeon played in its ecosystem is limited by lacking evidence and data. It is likely they played a great part in the
spread of mast trees due to their diet preference and large migration. White oak in particular, a favored acorn, is the dominant oak along much of the eastern United States where Passenger pigeons were concentrated. Canebrakes, ecosystems of American bamboo, were probably encouraged by the pigeons who opened the canopy and fertilized the ground with their droppings. The
decline of the American burying beetle is also possibly linked to passenger pigeons as their primary carrion source may once have been the pigeons. With their demise, the beetle has had to find other sources of less abundance. Though the beetle still exists, the once-widespread scavenger is limited to a few Oklahoma counties and two islands off Rhode Island.
In the early years of settlement, Passenger pigeons were one of the principal food sources that kept colonies alive and thriving. They were easy to catch, numerous, and a reliable source of food when crops weren’t ready for harvest. As colonies stabilized and populations grew, the Passenger pigeon went from
savior from starvation to dietary mainstay to sport, hobby, and a nuisance. Landowners feared them for ruining agriculture and jeopardizing timber holdings. Hunters shot them for simple fun and money.
Hunters developed a number of techniques for catching Passenger pigeons, but one such technique brought about the common phrase
stool pigeon. A single bird was caught live and its
eyes sewed shut. Most often, it was manipulated by string then by the hunter to look as if it were peacefully feeding as to encourage others to arrive. Once down, a net would be thrown over the flock. A single shot from a shotgun brought down handfuls. One record of hunting at a nesting site in Petoskey, Michigan recorded around
50,000 birds killed a day for months. So many Passenger pigeons were available that they were a cheap target to use as live targets in shooting galleries and skeet shooting contests.
The number of Passenger pigeons dwindled and no laws were around to protect them. A few attempts were made, but they were either limiting or too late. Contrary to popular thought, research shows that colonial nesting birds are some of the
most vulnerable to extinction. It can be driven through the
Allee effect where inverse density dependence is defined as a positive relationship between population density, survival, and reproduction. In other words, low population densities cannot support survival. Even though tens of thousands of Passenger pigeons remained when hunting started to die down, their survival relied heavily on being a vast colonial species. For that species, even that number was too few, and compounded with habitat destruction, their extinction was inevitable.
The last two Passenger pigeons to exist were
Martha and George. They resided in the Cincinnati Zoo in the early 1900s with a small flock, and were soon the sole survivors by 1909. By 1910, George died to leave Martha as the last known living Passenger pigeon. She stayed on exhibit for her remaining four frail years where many flocked to see her. Still, her treatment was cruel by the crowds who would
throw sand at her to make her walk, and her cage was often roped off. On
September 1, 1914, her crumpled body was discovered by the keeper. On that day, the Martha died and the Passenger pigeon was officially an extinct species.
Part of the demise of the Passenger pigeons was the lack of protection, but they are one of the driving forces for laws that now exist. In the late 1800s, the
Lacey Act was established as an attempt to help the Passenger pigeons. It prohibits illegally obtained game to be shipped across state boundaries, and it helps enforce wildlife protection laws. In the case of
Geer v. Connecticut, the U.S. Supreme Court upheld that states hold wildlife in trust for their people and has the power to ensure harvested game is kept for their benefit. The
Migratory Bird Treaty Act of 1918 is the key law to protection of native avian species. It protects all parts of native birds to the fullest degree. By federal law, even today, anything that once belonged to a native bird including, but not limited to, live birds, skins, feathers, eggs, and nests, are illegal to possess without a proper permit. In the early 1970s, more laws were enacted and toughed including the
Clean Air Act, Clean Water Act, National Environmental Policy Act, and the Endangered Species Act mainly in response to
Silent Springs by Rachel Carson that pointed to other threats to wildlife, in particular DTT and other pesticide use.
While mankind has learned since the extinction of the Passenger pigeon, it is still a question of whether we have learned enough. A report from the International Union for Conservation of Nature in 2010 announced that 30 percent of amphibians, 21 percent of mammals, reptiles, and fish, and 12 percent of birds are all at risk of extinction. Across the world,
131 mammals, 23 coniferous trees, 15 reptiles, 217 birds, and 208 amphibians face imminent extinction according to the Alliance for Zero Extinction. Threats to survival include habitat loss, global warming, pollution, and introduction of non-native species in various parts of the world. Whether or not we are in the
early to mid-stages of the sixth great extinction event on the planet has yet to be determined, but if nothing is done, it will be a guarantee.
This post is a direct copy from my original Google+ post from yesterday to mark the centennial of the extinction of the passenger pigeons. A few notes of additional information, particular references, are on that post. My previous passenger pigeon post on this blog can be found here. The only other information of particular importance is mention of the wonderful panels provided by Project Passenger Pigeon. The pdf files of the displays are available for use at the link provided.
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