Bearded Vultures Used To Moonlight As Museum Curators, Leaving Nests Full Of Historical Objects

Bearded vultures have been revealed as the somewhat surprising curators of natural museums, after scientists investigating centuries-old, abandoned nests discovered that they were packed with a whole host of well-preserved historical remains.

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Once found throughout the mountains and cliffs of southern Spain, bearded vultures are now extinct in these areas, having begun to disappear between 70 to 130 years ago. They did leave something behind, however – their nests.

Territorial raptors such as these birds tend to occupy the same nests over long periods of time, and the microclimate of the high-altitude areas where bearded vultures used to make them provides the kind of conditions that helps keep them preserved, even if the birds aren’t there to maintain them anymore. 

Curious about what might be hidden within such nests, researchers led by the Wildlife Ecology and Management Research Group of the Institute for Research in Game Resources (IREC – CSIC, UCLM, JCCM) set to finding some.

That involved consulting books written by naturalists who’d visited the area when the vultures were still there, and speaking to locals “in their 70s and 80s, who remembered because they had lived with the species or because a shepherd had told them something,” study author Sergio Couto explained in a translated statement.

In total, the team located over 50 well-preserved bearded vulture nests throughout southern Spain, and examined 12 of them in layer-by-layer detail.

Out of the 2,483 remains recovered, many of them could be expected. There were 2,117 bone remains – bearded vultures are the only birds in the world that primarily eat bones – as well as hooves, teeth, and egg shells.

What was less anticipated was the staggering number of artifacts originating from humans, which the researchers suggest were likely specifically used during nest building. The 226 anthropogenic remains included a fragment of a basket estimated to be at least 129 years old and a piece of ochre-painted sheep leather dating back somewhere between 673 to 629 years ago.

Oldest of all, and perhaps the most surprising, was what the authors dubbed an “extraordinary” complete sandal made out of esparto grass, thought to be between 652 and 696 years old. That takes us back all the way to the 14th century.

The team’s findings illustrate how examining these long-occupied nests could help us imagine something more of human life across such long periods of time. Not just the image of a Medieval Spaniard shaking their fist as a vulture flies off with their shoe, of course, but what kind of hunting weapons people were using (the nest hid a crossbow bolt and part of a slingshot), what they were wearing, and how they were crafting those materials.

It also helps us understand more about bearded vultures and the environment that they occupied over time, which could help scientists learn more about how they went extinct in southern Spain – and how to make sure that those left elsewhere stick around.

“The egg-shell remains discovered allow comparative toxicological studies using contemporary and museum samples to examine the evidence related to pesticide load and the local extinction history of the Bearded Vulture,” the authors write.

“This information is of the utmost importance for the recovery of the species at the European level, regarding, for example, the species' potential distribution and selection of suitable release sites, or to prioritize habitat conservation efforts.”

The study is published in the journal Ecology.