Endangered bearded vultures disappeared from the cliffs of southern Spain decades ago. But a peculiar legacy remains, one that offers a glimpse back in time more than 600 years.
The massive nests these vultures built are also a sort of guano-stained archive, full of human bric-a-brac dating as early as the 13th century. Scientists studying the vultures uncovered a trove of more than 200 human-made odds and ends when they picked through 12 abandoned nests.
The robust, long-occupied nests built in a dry climate in caverns sheltered from the elements “have acted as natural museums,” a team of Spanish scientists reported last month in Ecology. “This opens up future research initiatives to analyze the accumulated anthropogenic contents of ancient Bearded Vulture eyries.”
Add that to the list of benefits from this class of underappreciated scavengers. Recent research, for example, has found that vultures in India help control diseases that kill hundreds of thousands of people.
Bearded vultures are just one of the animals whose dwelling spaces double as messy historical records, thanks to their quest for building material and the human penchant for littering the world with our detritus. Packrat nests have shed light on more than a thousand years of human history in the desert Southwest of the United States and preserved insect DNA dating back more than 30,000 years. The U.S. Geologic Survey even maintains a database with detailed accounts of all the ancient treasures extracted from packrat middens.
In Spain, the scientists picked through the nests between 2008 and 2014, cataloguing 2,483 remains mixed in with sticks and other natural debris. That included 2117 bits of bone, 43 pieces of eggshell, 86 hooves, 72 chunks of leather and 126 scraps of clothing.
Some were likely part of the meals for these vultures, whose diet is made up largely of bones from carrion. But that doesn’t explain other items.
For example, what was a vulture doing with the tip of a wooden lance and a metal crossbow bolt? Or a woven shoe made from grass and twigs that was some 670 years old, according to radio carbon dating?
Then there were the slightly more enigmatic but nevertheless human-made items: A 650-year-old bit of sheep leather with red lines painted on it; a 150-year-old bit of a woven basket; and part of a slingshot made from braided grass.
While the researchers don’t offer any conclusions about what these items mean, such finds can offer insights into both the condition of surrounding ecosystems and the ways in which human societies evolved along with them, the scientists write.
The natural detritus could also provide valuable clues about the past. For instance, eggshells could be analyzed to look for evidence of historic exposure of the vultures there to toxic chemicals.
These vultures, meanwhile, are in danger of becoming historic curiosities themselves in Europe. For centuries the massive birds were shot and poisoned as pests. There are fewer than 500 breeding pairs left on the continent, nearly half of them in the Pyrenees.
There are signs of a comeback, thanks to recent conservation efforts. And there are other populations in parts of Africa, the Middle East and central Asia. But overall, the world has between 1,675 and 6,700 bearded vultures, and their populations are dwindling, according to the International Union for Conservation of Nature.
If these birds endure, who knows what modern-day refuse future scientists will be extracting from their nests. Bits of wire? Broken cell phones? A scrap of polyester clothing?
Margalida, et. al. “The Bearded Vulture as an accumulator of historical remains: Insights for future ecological and biocultural studies.” Ecology. Sept. 11, 2025.
Image:Animalia and Sergio Couto/Ecology 2025
