In a study published in the journal Ecology, archaeologists report the discovery of more than 200 human artifacts in the nests of bearded vultures. The scientists rappelled down cliffs to 12 abandoned nests of these bone-eating raptors, which vanished from the cliffs a century ago. Only 308 breeding pairs remain in Europe.

Bearded vultures build and maintain nests for long periods, sometimes for centuries, resulting in thick structures made of a variety of materials, including branches and bones. The scientists found well-preserved human items that were 150 to 675 years old, including leather items, fabric fragments, tools, a crossbow bolt and a slingshot. The most surprising discovery was a sandal made from woven esparto grass believed to be between 650 and 750 years old. The cool, dry conditions in the cliff caves preserved the artifacts.