A 2,200-year-old poop time capsule reveals secrets of the Andean condor

Much like tree rings, many layers of guano record the birds' responses to ecosystem changes

A photo of an Andean condor flying.

Andean condors (one shown) are one of the largest flying birds in the world. One population has returned to the same cliffside nest, generation after generation, for thousands of years.

LUIS ROBAYO/AFP/Getty Images Plus

For over 2,000 years, Andean condors have been nesting — and pooping — in the same cliffside grotto high in the Andes.