Birds
Passenger Pigeon
Ectopistes migratorius · also called passenger pigeon, wild pigeon
Two hundred years ago, the passenger pigeon may have been the most numerous bird on Earth. Migrating flocks a kilometre wide took days to pass and blotted out the sun; nesting colonies covered hundreds of square kilometres and broke the trees they roosted in. Within about fifty years there were none left at all, and the last one died alone in a zoo cage in 1914.
Overview
The passenger pigeon lived in the deciduous forests of eastern North America, ranging widely to follow the annual nut crop. It was 39–41 cm long, the male slate-grey with a bronze-and-pink breast. It fed mainly on acorns, beechnuts, and chestnuts.
The most abundant bird
Estimates put the population at three to five billion — perhaps a quarter of all land birds on the continent. It bred in enormous colonies and seems to have needed those huge numbers to reproduce at all, by overwhelming predators.
The collapse
Once railroads and the telegraph let hunters find and reach the flocks, the birds were shot and netted by the wagonload for cheap city meat, and nesting colonies were raided for squabs. The killing far outpaced a bird that laid one egg per nest, and once the flocks were thinned past a point, the survivors could no longer form colonies large enough to breed. Loss of the eastern hardwood forests finished it.
Martha
The last confirmed wild bird was shot around 1901. The last of the species, a female named Martha, died at the Cincinnati Zoo on 1 September 1914. Her body is still held at the Smithsonian.
Legacy
The pigeon’s disappearance helped drive the first US wildlife protection laws, and a de-extinction project is now attempting to recreate it using the band-tailed pigeon.
Passenger Pigeon: common questions
How many passenger pigeons were there?
More than of any other bird in North America and possibly any bird in the world. Nineteenth-century observers described single migrating flocks estimated at over a billion birds, moving in a river of wings a kilometre or more wide that took many hours, sometimes more than a day, to pass a given point. Adding up the flocks and colonies, ornithologists have estimated a total population of three to five billion at its peak. That the same bird went completely extinct within the lifetime of people who had seen those flocks is one of the starkest facts in the history of wildlife.
How could such an abundant bird go extinct so fast?
Two things combined. First, an unprecedented level of killing. The birds were highly concentrated and predictable when they nested and roosted, and with railroads to carry hunters in and carcasses out, and the telegraph to report where the flocks were, professional hunting became an industry. Nesting colonies were attacked directly, destroying that year's young. Second, the bird's own biology. It laid only one egg per nest, bred slowly, and appears to have needed to nest in immense colonies to reproduce at all, probably by swamping predators. Once the flocks were thinned past a certain point, the survivors could no longer form colonies large enough to breed successfully, and the population fell even without further hunting. Loss of the eastern hardwood forests that produced its food added to the collapse.
Who was Martha?
Martha was the last passenger pigeon. She was one of a small captive flock kept at the Cincinnati Zoo, and as the others died she became, for years, the only known member of her species anywhere. She died in her cage on 1 September 1914, at about 29 years old. Her body was frozen in a block of ice, sent to the Smithsonian, and mounted, and it is still held there. She has become a symbol of human-caused extinction, and the date of her death is sometimes marked as a day of remembrance for lost species.
Could the passenger pigeon be brought back?
There is an active de-extinction project that aims to do so, using the band-tailed pigeon, the passenger pigeon's closest living relative, as a genetic starting point and a surrogate. The idea is to edit band-tailed pigeon cells to carry key passenger pigeon genes recovered from museum specimens, then breed birds that look and behave like the extinct species. The scientific hurdles are large, and even if a bird could be produced, questions remain about whether a species that depended on flocks of billions could ever function in today's fragmented forests. For now the passenger pigeon exists only as museum skins and as a cautionary tale.