THE GREAT PASSENGER PIGEON COMEBACK
About the Passenger Pigeon
The Passenger Pigeon was an ecosystem engineer of eastern North American forests for tens of thousands of years – before the first humans set foot on the continent. Their large and dense flocks created forest disturbances and put regeneration cycles into motion. Huge, dense, nomadic flocks constantly moved from one area to another, shaping a mosaic forest landscape of successive patchwork habitats that supported rich and biodiverse ecosystems.
Over a century after the extinction of the passenger pigeon, we’re still learning about this incredible species. Watch the video to learn more.
After 12 million years of evolution, Passenger Pigeons were wiped out by Anglo-American citizens in the span of just 40 years. Starting in the 1860’s the pigeons were harvested at industrial scales to feed U.S. and Canadian communities growing rapidly from immigration. Today, nearly 150 years after their vast flocks produced their last forest disturbance, the regime of species that co-evolved to live with the pigeons is in decline. Despite vast reforestation over the past century, the familiar wildlife that inspired the transcendentism movement, are disappearing as heterogenous, richly dynamic forests have been overtaken by homogenous closed canopy habitats.
The Passenger Pigeon lived in dense flocks because of a unique behavioral trait: their social breeding. Unlike their relatives the Band-tailed Pigeons, which will nest in densities of one nest per three to four acres, Passenger Pigeons nested in densities of up 20,000 nests per acre, dozens to hundreds of nests per tree. When roosting, they were so hyper-social that the birds would line branches perched shoulder to shoulder and even sit on each other’s backs. There are historic accounts of roosting pigeons bending the crowns of young trees down to the forest floor under their combined weight.
The Passenger Pigeons’ morphological and physiological traits were shaped by their hyper-social nature. Passenger Pigeon hatchlings grew up rapidly and were able to fly in less than 20 days, the shortest development time of all pigeons of similar size. This rapid growth meant that breeding Passenger Pigeons could leave nesting sites quickly before exhausting the local food supply.
Male and female Passenger Pigeons looked different, which is a rare trait among the world’s more than 350 species of pigeons and doves. The birds’ appearance may not seem important to the Passenger Pigeon’s ecological function, but a bird’s plumage is key to how mates are chosen in social flocks. The red breasts of males were likely a signal of superior fitness to females seeking the best mate in a crowd. The graduated tail of the Passenger Pigeon, another rare trait among pigeons and doves, was likely also used in courtship displays and influenced mate choice. All these traits – behavior, plumage, growth rate – will be necessary to recreate a new generation of passenger pigeons that can resume the ecological role of their historic counterparts.
Painting by Louis Agassiz Fuertes; Photographs by Ben Novak.
