Passenger pigeon

Name and taxonomy

The passenger pigeon sat in the pigeon and dove family, Columbidae. Its genus name means moving about, and the species name points to migration. The English name comes from a French word for passing by. People also called it the wild pigeon, the blue pigeon and the wood pigeon.

Carl Linnaeus treated this bird and the mourning dove as one species in 1758. William Swainson gave it a genus of its own in 1827. The long tail and the shape of the wings were his reasons. A ruling in 1955 finally fixed a separate name on each of the two birds. Indigenous names include amimi in Lenape, omiimii in Ojibwe and jahgowa in Seneca. The Seneca name meant big bread, because the bird fed the people.

Evolution and relatives

The oldest fossil of the genus is a single wing bone from North Carolina. It comes from rock laid down in the Pliocene, several million years ago. Bone shape once put the Zenaida doves closest to the passenger pigeon. Some writers even placed the mourning dove in the same genus.

DNA work in 2010 and 2012 moved the nearest place to the Patagioenas pigeons. The band-tailed pigeon of western North America is one of that group. The ancestors may have reached the New World from South East Asia. The bird had no subspecies. It crossed with a Barbary dove in one aviary, but the young could not breed. A genome study in 2017 found low genetic variety despite the huge population.

Appearance

An adult male measured 39 to 41 centimetres and a female 38 to 40. The weight of the bird ran from 260 to 340 grams. The male had a blue-grey head, nape and hindneck. Feathers on the side of the neck flashed bronze, violet or gold as he turned. The breast was a rich pink that faded to white on the belly.

Black spots marked the wing coverts, and the outer tail feathers were white. The bill was black, the legs coral red, and the iris deep red. A female was duller, browner and shorter in the tail than her mate. A young bird looked scaled, because pale edges rimmed the wing feathers. The wings were long and pointed and the tail was wedge-shaped. Heavy breast muscles and a keel 25 millimetres deep powered the flight.

Habitat and range

The species held North America east of the Rocky Mountains. Its range reached from the Great Plains east to the Atlantic shore. The deciduous forests of the east were its main ground. Most breeding took place around the Great Lakes and in southern Ontario. Band-tailed pigeons may have kept the species out of the western woods.

Winter flocks lay from Arkansas and Tennessee south to Texas and northern Florida. The birds liked large swamps with alder, or pine woods when no swamp was near. Strays turned up in Cuba, Bermuda, Mexico and even in Scotland and Ireland. More than 130 fossils have been found across 25 states. Some are 100,000 years old and lie well west of the historic range.

Diet and feeding

Beech and oak mast carried the flocks through autumn, winter and spring. Beechnuts, acorns and chestnuts were the main food in those seasons. In summer the birds turned to blueberries, grapes, cherries and mulberries. They also took worms, caterpillars and snails, above all while breeding. Buckwheat and other grain went the same way when a flock found a field. The birds were very fond of salt and gathered at brackish springs.

A feeding flock rolled forward as birds at the back flew over to the front. The birds turned over leaves, soil and snow with their bills. A flock could strip almost every nut and berry from its path. Birds flew 100 to 130 kilometres from the roost and back in a day. A joint in the lower bill let a pigeon swallow an acorn whole. The crop stretched to the size of an orange and held 17 acorns or 28 beechnuts.

Behaviour and social life

The passenger pigeon was nomadic and never stayed long in one place. On migration it averaged about 100 kilometres per hour. Flocks flew in narrow twisting columns that rose and fell together. They passed as low as 1 metre in wind and as high as 400 metres. John James Audubon watched a flight in 1813 that ran for three days.

One flock in southern Ontario in 1866 measured 1.5 kilometres wide. That flock was reported as 500 kilometres long and took 14 hours to pass. Roosts covered anything from a few acres to 260 square kilometres. Birds piled on each other's backs, and thick branches snapped under the weight. Dung built up below a roost to more than 0.3 metres deep. On the ground the bird was awkward and walked in short jerky steps.

Communication and senses

The noise of a flock was deafening and could be heard from far off. Listeners called the voice loud, harsh and unmusical. The birds croaked while they built nests and made bell-like notes while mating. An alarm note from one feeding bird set the whole flock calling and rising.

Wallace Craig wrote the calls down in 1911 from birds held in an aviary. A short keck served to draw the notice of another pigeon. A scolding series was aimed at a mate or at an enemy. A drawn out note could bring a passing flock down into a nearby tree. Females called far less often than males. Sharp eyes and long flights let the flocks find mast over a wide country.

Reproduction and life cycle

The birds probably bred once a year, and the whole cycle took about 30 days. Flocks reached the nesting ground in March in the south and later in the north. Nesting colonies were known as cities and could cover thousands of hectares. The largest on record stood in central Wisconsin in 1871. It covered 2,200 square kilometres, and counts ran to well over a hundred million birds.

Courtship took place on a branch rather than on the ground. The male flapped his wings hard, called, and pressed against the female. A willing female pressed back, and the pair preened and billed. The nest took two to four days and used 70 to 110 twigs. It formed a loose shallow bowl thin enough to see the egg through. Nests sat from 2 to 20 metres up, often more than 50 in one tree.

One white egg was normal, about 40 by 34 millimetres. Both parents sat on it for 12 to 14 days. The squab hatched blind under thin yellow down. It fed on crop milk at first and matched its parents in weight within 14 days. After 13 to 15 days the adults fed it once more and left the colony together. The young bird dropped to the ground, begged from other adults, and flew days later.

Predators and threats

A nesting city drew minks, weasels, martens and raccoons to the eggs and young. Owls, hawks and eagles took nestlings and adults alike. Wolves, foxes, bobcats, black bears and cougars picked up fallen young. Cooper's hawk was so good at the work that people called it the great pigeon hawk.

The size of a flock protected each bird, and hunters took only a small share. An undisturbed colony was thought to raise about 90 per cent of its young. Swamping the predators may be one reason the birds crowded together. Weather killed many, and spring freezes caught flocks that moved north too early. Two kinds of feather louse lived on the bird. No record exists of a wild passenger pigeon dying of disease.

Population and conservation

No bird in North America was ever more abundant than this one. One researcher put it at 25 to 40 per cent of all land birds in the United States. Numbers fell slowly between about 1800 and 1870. The fall then turned into a crash between 1870 and 1890. The last great nesting was at Petoskey in Michigan in 1878. Hunters killed 50,000 birds a day there for nearly five months.

Protection laws existed, but they were vague and nobody enforced them. An Ohio committee in 1857 ruled that the bird was too prolific to need help. The last wild nest and egg were taken near Minneapolis in 1895. A male shot near Oakford, Illinois, in 1901 is the last certain wild record. Martha died on 1 September 1914, and the IUCN lists the species as Extinct.

At least 1,532 skins and 16 skeletons survive in museums around the world. The loss of the bird pushed the young conservation movement into new laws. The IUCN still cites the species when a common animal is called at risk. One group now works on rebuilding the genome from museum skins. Critics say the money would probably save more if it went to living species.

Relationship with humans

Indigenous people ate the bird for thousands of years before Europeans arrived. Many took only the fat young, at night, with long poles. Some nations counted disturbing the adult birds as a crime. The fat was stored in quantity and used in the way people use butter. In the south-east only the wild turkey mattered more as game.

European hunting was heavier from the start. Men at Fort Caroline killed close to 10,000 pigeons in seven weeks in 1565. Commercial netting and shooting began in the early nineteenth century. Railways then carried barrels of dead birds to city markets. The telegraph told the trappers where the next flock had settled. One town shipped 1.8 million pigeons in 1851 alone.

At least 600 people worked as pigeon trappers in 1874, and 1,200 by 1881. Live birds were used as targets, and one contest demanded 30,000 kills to win. Feathers filled beds and pillows across the eastern states. Chemists sold the blood, the stomach lining and the dung as medicine. Farmers treated a feeding flock as a plague on the crop.

In culture and myth

In Wyandot belief a dead person's soul turned into a passenger pigeon. The change was said to come round with the Feast of the Dead, every twelve years. In Seneca tradition a white pigeon led the colony and a Council of Birds sent it. Seneca people left wampum and brooches for the old birds before taking the young. They kept a pigeon dance as a way of giving thanks.

In Ho-Chunk custom the bird belonged to the chief and was served at his feast. In Choctaw the name meant lost dove. Early colonists read a huge flight as a warning of sickness to come. Audubon painted the best known picture of the bird for The Birds of America.

Aldo Leopold spoke at a monument to the species in Wisconsin in 1947. He said that in time only the hills would remember the bird. A statue of Martha stands at Cincinnati Zoo beside the hut where she lived. Her mounted body has been called a monument to extinction. Writers, painters and songwriters still return to the story.