Present-day risk assessment would have predicted the extinction of the passenger pigeon (Ectopistes migratorius)

The precipitous decline and extinction of the passenger pigeon one century ago helped galvanize implementation of national policies and international cooperation on wildlife management. Having a clear understanding of past conservation failures will aid in preventing future unanticipated extinctions. Simulations from a population model developed for this species indicate that while habitat loss contributed to decline, the main cause of the extinction was an unregulated commercial harvest. Hindcast application of the IUCN's Red Listing criteria to modeled population trajectories show that the species would have been listed as threatened for decades prior to extinction had the data and risk-assessment methods been available. Abundant populations can belie indicators of extinction-risk such as a high rate of population decline. Listing species as threatened based solely on rates of decline remains controversial; however this study demonstrates that this risk-indicator may have been the sole means by which the risk to the passenger pigeon could have been detected early enough for effective conservation measures.