The last passenger pigeon died more than 100 years ago, but scientists still puzzle over how a bird once numbering as many as 5 billion disappeared so quickly from North American skies. “Hunters with guns,” is the big answer — but why didn’t small populations of pigeons survive anywhere? New research into passenger pigeon genetics may provide some clues. Among other findings, the study, published recently in Science, suggests the birds’ adaptation to living in large groups may have left them ill-equipped to quickly thrive in smaller numbers. As co-author Beth Shapiro explains, the research — which involved studying a number of complete and mitochondrial passenger pigeon genomes, as well as genomes from a close relative, the band-tailed pigeon — overturns a previous theory about why passenger pigeons went extinct so quickly. “A few years ago, a study was published that suggested that their populations actually fluctuated quite considerably over time and that this might have meant that t
