page_title: Passenger pigeon
section_title: Reproduction
hierarchical_section_title: Passenger pigeon / Ecology and behavior / Reproduction
caption_attribution_description: Nesting passenger pigeon.
context_page_description: The passenger pigeon or wild pigeon is an extinct species of pigeon that was endemic to North America. Its common name is derived from the French word passager, meaning "passing by", due to the migratory habits of the species. The scientific name also refers to its migratory characteristics. The morphologically similar mourning dove was long thought to be its closest relative, and the two were at times confused, but genetic analysis has shown that the genus Patagioenas is more closely related to it than the Zenaida doves.
  The passenger pigeon was sexually dimorphic in size and coloration. The male was 390 to 410 mm in length, mainly gray on the upperparts, lighter on the underparts, with iridescent bronze feathers on the neck, and black spots on the wings. The female was 380 to 400 mm, and was duller and browner than the male overall. The juvenile was similar to the female, but without iridescence. It mainly inhabited the deciduous forests of eastern North America and was also recorded elsewhere, but bred primarily around the Great Lakes.
context_section_description: Other than finding roosting sites, the migrations of the passenger pigeon were connected with finding places appropriate for this communally breeding bird to nest and raise its young. It is not certain how many times a year the birds bred; once seems most likely, but some accounts suggest more. The nesting period lasted around four to six weeks. The flock arrived at a nesting ground around March in southern latitudes, and some time later in more northern areas. The pigeon had no site fidelity, often choosing to nest in a different location each year. The formation of a nesting colony did not necessarily take place until several months after the pigeons arrived on their breeding grounds, typically during late March, April, or May.
  The colonies, which were known as "cities", were immense, ranging from 49 ha (120 acres) to thousands of hectares in size, and were often long and narrow in shape (L-shaped), with a few areas untouched for unknown reasons. Due to the topography, they were rarely continuous. Since no accurate data was recorded, it is not possible to give more than estimates on the size and population of these nesting areas, but most accounts mention colonies containing millions of birds. The largest nesting area ever recorded was in central Wisconsin in 1871; it was reported as covering 2,200 km² (850 sq mi), with the number of birds nesting there estimated to be around 136,000,000. As well as these "cities", there were regular reports of much smaller flocks or even individual pairs setting up a nesting site. The birds do not seem to have formed as vast breeding colonies at the periphery of their range.
  Courtship took place at the nesting colony. Unlike other pigeons, courtship took place on a branch or perch. The male, with a flourish of the wings, made a "keck" call while near a female. The male then gripped tightly to the branch and vigorously flapped his wings up and down. When the male was close to the female, he then pressed against her on the perch with his head held high and pointing at her. If receptive, the female pressed back against the male. When ready to mate, the pair preened each other. This was followed by the birds billing, in which the female inserted its bill into and clasped the male's bill, shook for a second, and separated quickly while standing next to each other. The male then scrambled onto the female's back and copulated, which was then followed by soft clucking and occasionally more preening. John James Audubon described the courtship of the passenger pigeon as follows:
  Thither the countless myriads resort, and prepare to fulfill one of the great laws of nature. At this period the note of the Pigeon is a soft coo-coo-coo-coo much shorter than that of the domestic species. The common notes resemble the monosyllables kee-kee-kee-kee, the first being the loudest, the others gradually diminishing In power. The male assumes a pompous demeanor, and follows the female, whether on the ground or on the branches, with spread tail and drooping wings, which it rubs against the part over which it is moving. The body is elevated, the throat swells, the eyes sparkle. He continues his notes, and now and then rises on the wing, and flies a few yards to approach the fugitive and timorous female. Like the domestic Pigeon and other species, they caress each other by billing, in which action, the bill of the one is introduced transversely into that of the other, and both parties alternately disgorge the contents of their crop by repeated efforts.
  After observing captive birds, Wallace Craig found that this species did less charging and strutting than other pigeons (as it was awkward on the ground), and thought it probable that no food was transferred during their brief billing (unlike in other pigeons), and he therefore considered Audubon's description partially based on analogy with other pigeons as well as imagination.
  Nests were built immediately after pair formation and took two to four days to construct; this process was highly synchronized within a colony. The female chose the nesting site by sitting
caption: Nesting captive bird, wary of the photographer
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