Birding Business July 2014 - Cover Story

Farewell Martha - How 5 Billion Birds Vanished

BY HANK WEBER | Contributing Author

MARTHA WAS TRULY ALONE.  Living in the Cincinnati zoo, she was the last Passenger Pigeon remaining on earth.  Her parents were dead.  She had no living brothers or sisters.  No relatives or friends.  No one.  She was 29 years old, and the last of her kind.  When Martha died a century ago (September 1, 1914) Passenger Pigeons ceased to exist. 

Zookeepers rushed her lifeless body to the Cincinnati Ice Company.  Held by her feet, she was lowered into a tank of water, frozen upside down into a 300-pound block of ice and shipped to the Smithsonian Institution where her lifeless corpse remains on display today.  A simple sign reads: “Extinct”.

Passenger Pigeons differ from common city pigeons.  Though similar in shape, they were 50% larger.  The name comes from the French word “passage”, meaning to pass by.  And pass by they surely did - - in unimaginable numbers.

Passenger Pigeons were once the most abundant birds in the country.  Reliable estimates place their total numbers at up to 5 billion individuals, more than 30% of all birds – possibly the most abundant bird that ever lived on earth.  Ornithologists reported flocks over one mile wide and 20 miles long that literally “blacken the sky”.  Audubon observed a migration flight so enormous it took two days to pass.  A single roost site might contain 5-7 million birds.  They were numerous and widespread.  If you combine all of today’s “trash” birds (Starlings, House Sparrows, etc.)  the total would fall far short of the pigeon. 

With such a massive population the possibility that Passenger Pigeons could become extinct was inconceivable.  Yet in less than a century they were gone.  From 5 billion individuals to Martha, to none. 

How could a species so incredibly abundant become extinct in such a short time?  How did 5 billion birds disappear?  What caused their dramatic decline?  If you suspect humans played a lead role, you are on the right track.  Although there was no single cause, man tipped the balance of nature – loss of habitat combined with extensive hunting were two major contributors.

As vegetarians their primary food source was “mast” — a general term for the seeds and ripening fruit of hard wood and fruit bearing trees.  They loved beechnuts, acorns, and maple and elm seeds.  A large flock could quickly strip a small woodlot of all edible food.  Then the flock would move on.  Pigeons, like waxwings today, were semi-nomadic, constantly on the move to find food.  Fortunately, different types of mast matured at different times during the year.  But only a fairly large forest could produce enough mast to satisfy a huge army of pigeons. 

The eastern half of the country was once heavily forested.  However, as human population mushroomed, civilization moved inland from the coast.  Forests were rapidly cleared for farming, industry and cities.  As the remaining forests shrunk in size, finding ample food became more challenging for Passenger Pigeons.
Loss of food sources was not the only peril.  Hunting was a more lethal danger.  Early settlers quickly learned that pigeon meat was tasty, and pigeons were plentiful and easy to kill.  Subsistence hunting to feed the farm family was not the major problem.  Rather it was professional trappers and market hunters who killed pigeons in quantities sufficient to feed an entire city. 

One throw of a net onto a sleeping roost could capture hundreds of birds.  A single shot might kill 5, 10 or more.  The supply seemed inexhaustible.  In 1874 at one roost in Michigan, a group of market hunters bagged 25,000 birds a day for 28 straight days.  In the 1800s there were an estimated 800 to 1000 professional market hunters. They used scouts and the newly developed telegraph system to track the exact location of pigeon flocks.  Following flocks from site to site, they methodically slaughtered the birds.  The result was a huge mound of dead pigeons, an inexpensive source of meat protein.  Hundreds of birds were stuffed into a barrel, packed with ice and shipped by rail to major cities.  Boxcars full of birds.  One hunt in upper New York State is said to have used over 15 tons of ice.  235,000 pigeons were shipped out of Grand Rapids, Michigan on just one day in 1860.  In 1771 Boston markets sold 50,000 pigeons per day. 

Squab (a young pigeon nestling) was particularly flavorful and highly prized.  Pigeon hunters preferred the squabs.  As a result, few young grew to produce future generations.  Reproduction rates were drastically reduced and population numbers plunged into a downward spiral toward zero.  Remaining adults eventually died a natural death.  Despite their once enormous numbers, Passenger Pigeons were dying out.

The passenger pigeon was never studied in nature. It nested in pairs, in small groups, large groups, and huge groups (100,000,000 plus). No one knows how many of the small groups successfully fledged young. We do know that Buttons, an immature female shot in spring 1900, was born in 1899 when there already were virtually no birds left. Presumably they did best in big flocks, but just when their numbers declined to the point of no return, no one knows.

The total population of all the currently endangered species (California Condor, Whooping Crane, Kirtland’s Warbler and others) is probably in the low thousands of birds, not hundreds of thousands or millions of individuals.  If 5 billion pigeons could disappear, so could today’s smaller populations if things don’t change.  Since human activity contributes to the decline of a species, changes in human activity can reverse the trend.  The banning of DDT halted the threat to Bald Eagles and Ospreys,  California Condors are flying free in the wild again – all the result of direct help from caring humans.

In the last two centuries, five species have become extinct in the U.S.  Currently the U.S. Fish & Wildlife Service lists about 50 species and subspecies as “endangered” in the continental US.  An additional 20 species are endangered in the Hawaiian Islands. 

Current populations of these species are very small.  But as the plight of the passenger pigeon vividly demonstrates, sheer numbers do not guarantee future well-being.  The most common birds in your backyard could also be at risk.  Paying careful attention to what is happening in your yard, your city and your area can prevent another bird, maybe that cheerful Robin on your lawn, from joining Martha on display at the Smithsonian.

Extinct and Endangered
Since the first European settlers arrived in the new world, 5 of the more than 800 species have become extinct.  Interestingly, during the same time period, no European birds became extinct.

Extinct Species
In the chronological order of their last sightings, the following birds became extinct:
Great Auk - This powerful swimming and diving bird was similar to penguins in the fact that it could not fly.  Most comfortable in water, it was common along the eastern shores.  They were last seen on US shores in the early 1800s.  Hunting was the primary cause of its decline.  The last confirmed pair in the world was shot near Iceland in 1844.

Labrador Duck - Little is known about this diving duck related to scoters that wintered along the northeast coast.  Never very abundant or even common, by the 1840s it was rare.  The last collected (shot) specimen was taken along New York’s Long Island coast in 1875.

Carolina Parakeet - This colorful, parrot-like bird inhabited the southern states.  In 1904 Frank Chapman reported the last small flock seen in the wild in Florida.  The last captive bird died in 1914, just a month earlier than the last captive passenger pigeon.  Carolina Parakeets were trapped for sale as caged birds, shot to provide colorful feathers for the millinery trade and slaughtered by farmers protecting fruit trees and grain fields.

Heath Hen - A race of the greater prairie chicken, by 1900 the total number of these grouse-like birds of the scrubby oak plains of the eastern seaboard was less than 50-60 individuals.  After a sanctuary was established on the island of Martha’s Vineyard the population of protected birds increased to around 2,000.  However, a wildfire in 1916 destroyed their habitat.  The last bird, a male, was seen in 1932.

Dusky Seaside Sparrow - Considered a subspecies of the seaside sparrow, this darker species had the most limited geographic territory of any bird (only about 10 miles of coastal marshes around Merritt Island, Florida.).  Their demise began in the 1940s with the use of DDT to control mosquitoes.  By the late 1970s, the total population was estimated at less than three dozen individuals.  In 1983 the last 4 birds, all male, were taken to Disney World’s Discovery Island in Orlando to live out their lives.  The last one, called Orange Band after the color of his leg band, died in June 1987. (There were also mystery birds like the carbonated warbler and blue mountain warbler, reported by Audubon and Wilson, but whose status has never been adequately determined)

** (The spectacled cormorant, which was endemic to the Aleutians, disappeared early.) 

Species in Limbo
The exact status of some species is in question.  The species may be extinct, maybe not.  What is known is that there have not been any verifiable sightings for decades.  The lack of sightings may simply be because the populations are small and favor very remote habitat. Or it could mean there are no remaining individuals to be seen.

The birds in this undetermined category include Eskimo curlew (also prized by market hunters), Bachman’s warbler and Ivory-billed woodpecker.  Recent highly publicized but unconfirmed sightings of the ivory-billed raised hope that these birds still live.

Species in Danger of Possible Extinction
In January 2014, the U.S. Fish & Wildlife’s official list identified about 50 species as “endangered” in the continental states.  The best known are the California condor, whooping crane, everglade snail kite, northern spotted owl, Kirtland’s warbler and others.  An additional 20 species are endangered in Hawaii.