BETWEEN 900 and 1200 a group of native Americans lived in Chaco Canyon, in what is now north-western New Mexico. They were part of the peoples known as the Ancestral Pueblo. They traded extensively with communities in the distant south: items such as cocoa beans, copper bells and jewellery made from marine shells have been found in Pueblo Bonito, a multi-storey great house in the canyon with over 600 rooms. But none of these remains have presented archaeologists with more of a quandary than the parrots.

The bones of 35 scarlet macaws have been excavated from various sites in the area. Birds play an important role in native American mythology, and parrots became part of the culture of some groups. Parrots were kept as pets and their feathers were highly prized. But since the nearest natural population of these birds is—and was—some 2,000km away, the question has been how so many of these parrots could have ended up in this canyon.

Archaeologists have known that the breeding of macaws began at Paquimé, near the modern-day city of Chihuahua, in Mexico, because the site has dozens of preserved egg shells and the skeletal remains of several hundred birds. But that was in about 1250, long after the parrots first turned up in Pueblo Bonito.

In those ancient times the people of the American south-west had no horses, wagons or waterways to connect them to the distant regions of south-eastern Mexico where wild scarlet macaws are found. Archaeologists had presumed that these birds were brought by traders on foot across the desert that makes up much of the centre of Mexico. Doubtful that many macaws would survive such a treacherous journey, however, Douglas Kennett of Pennsylvania State University and Stephen Plog of the University of Virginia collaborated with a group of colleagues to see if there were any genetic clues in the parrots’ remains.

The researchers collected DNA samples from the bones of the Chaco Canyon birds, along with a smaller sample of contemporary macaw bones from the Mimbres region in southern New Mexico. In total, they were able fully to reconstruct the mitochondrial genomes of 14 macaws. Surprisingly, they found an exceptionally low genetic diversity between the birds. As they report in Proceedings of the National Academy of Sciences this week, all of the macaws that lived in the Chaco Canyon region between 900 and 1200 were very closely related to one another.

Not stunned

Although it is possible that a small population living along the very northern natural range of macaws was visited by traders collecting birds, and that this resulted in the parrots of Chaco Canyon all being relatives of one another, it is something that the researchers believe to be extremely unlikely. Their alternative theory is that a few macaws were carefully nurtured during the arduous trek across central Mexico and then used to establish a breeding programme somewhere in the south-western United States or northern Mexico long before Paquimé got in on the act. Where that earliest of breeding colonies might have been remains a mystery, but that it might have existed at all is further testament to how treasured parrots were.