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The extinction of the passenger pigeon (Ectopistes migratorius) in the early 20th century is often attributed to overhunting by humans. However, a closer examination of the available evidence suggests that habitat loss and disease, not hunting, were the primary drivers of the species' rapid decline and eventual extinction. First, the passenger pigeon depended on vast tracts of mature beech and oak forests in eastern North America for both food and nesting. During the late 19th century, extensive logging cleared nearly 80% of these forests for agriculture and urban development. This fragmentation reduced the pigeons' primary food sources—acorns and beechnuts—and disrupted their breeding colonies, which required forest areas of at least 100 square kilometers. Without such large, connected habitats, the pigeons could not maintain viable populations. Second, the species was highly susceptible to a parasitic disease, Trichomoniasis, which spread rapidly in dense flocks. Historical records from the 1880s describe numerous sick and dying pigeons exhibiting symptoms consistent with this infection, such as lethargy and swollen throats. The disease likely weakened the birds and lowered their reproductive success, especially as stress from habitat loss increased their vulnerability. Third, hunting pressure was actually concentrated in the eastern United States, but passenger pigeons were also abundant in the western parts of their range, where hunting was minimal. Yet, declines occurred simultaneously across the entire range, suggesting a factor more widespread than localized hunting. Thus, the evidence points to habitat destruction and disease as the main causes, with hunting playing only a minor role.

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