Archaeology and the Passenger Pigeon Genome

Searching for new evidence as to why the population of passenger pigeons collapsed so spectacularly in the nineteenth century, Taiwanese geneticist Chih-Ming Hung and his colleagues took a close look at the birds' genome. They found evidence for repeated population bottlenecks; that is, they think the birds' population has fluctuated dramatically in the past, perhaps coming close to extinction several times. Their explanation for the birds' extinction is that human hunting and habit destruction did not wipe out the whole huge population on their own, but only worsened a crash that seems to have been typical of the species.

This fits well with the findings of archaeology. In 1800 passenger pigeons were the most numerous birds in the world, and flocks were reported that numbered in the billions. Aha, you must be thinking -- at least if you are an archaeologist -- what a fantastic food source for ancient Native Americans, the salmon of the east coast. And accounts written by European explorers in the 1700s do describe some of the clever ways Indians had found to trap hundreds of birds at a time. But if you look in the trash heaps of Indians who lived in the Late Woodland and Mississippian periods (AD 1000 to 1600) you find only a few passenger pigeon bones. The most common view among archaeologists is that the passenger pigeon boom of 1700 to 1850 was a new phenomenon created by the near extinction of the Indians, plus environmental changes such as the Little Ice Age, the rapid growth of new forests on land Indians had farmed, and the replacement of carefully tended and rather small Indian farms with the space-wasting but labor-efficient farms of European Americans, which were much easier for birds to rob. So the collapse of passenger pigeon populations in the 1800s was not the destruction of an ancient resource like the slaughter of the plains bison, but a classic boom and bust, both created and then ended by Europeans and the environmental changes they set in motion.

Nice to see genetic evidence that passenger pigeons were prone to the sort of booms and busts that the archaeology of the past 500 years suggests.