How such a large, stable population could abruptly vanish has long puzzled scientists. Now, a genomic analysis of conserved pigeon specimens sheds light on how the extinction occurred. Researchers were able to show that the passenger pigeon population did not have much genetic diversity compared to living pigeon species, which they believe made it less able to survive human pressures.
G.G.R. Murray et al., “Natural selection shaped the rise and fall of passenger pigeon genomic diversity,” Science, doi:10.1126/science.aao0960, 2017.