Bones, wool… but also footwear, pieces of basketry, leather, even a crossbow bolt, all collected by Bearded Vultures in their nest over (a long) time. At first glance, these items seem out of place, but they reveal a fascinating story about the history of vultures and people living side by side.
What do you think you could find in a Bearded Vulture (Gypaetus barbatus) nest? Bones and wool for sure, maybe feathers. The biologist Sergio Couto of the University of Granada and his team discovered that Bearded Vulture nests can store unusual pieces of human history: footwear, pieces of a basket, leather and even a crossbow bolt. These findings might look out of place in a vulture nest, but they tell us something about humans and vultures history alike. The study “The Bearded Vulture as an accumulator of historical remains: Insights for future ecological and biocultural studies”, published on the American Journal “Ecology”, shines a new light on Bearded Vultures.
The team visited more than 50 well-preserved historical Bearded Vulture nests in Southern Spain, where the species became extinct around 70-130 years ago. They analysed the content of 12 nests and found over 200 anthropogenic remains together with bones and eggshell fragments. The reason behind these apparently curious findings must be researched in Bearded Vultures ecology and behaviour. Their nesting habits could be the key for future long-term ecosystem monitoring and interdisciplinary research.
A winged antique collector
Bearded Vultures (Gypaetus barbatus) are the rarest vulture species in Europe. The species is well known for its distinctive colours and feeding habits. In fact, it is the only vulture species that feeds primarily on bones. Another important – but often overlooked – characteristic of the species is their territoriality.
Bearded Vultures establish and protect territories as big as 200-400 km2 and build their large nests in protected cavities on cliffs. Several generations of vultures reuse the same nest over decades and even centuries. Using their beak and talons, the parents collect material from their surroundings and use it to fill the nest to keep the eggs and the chicks warm. The nesting ledges are so carefully selected that almost no other animal can enter them, and they are protected from rain and wind. Thanks to these perfect microclimatic conditions, every piece of material collected by the birds remains in perfect condition over time.
(A) Hooves typical of ungulate limb remains.
(B) Diverse mammal and bird bones and teeth found in the same nest, some partially digested.
(C) The remains of Bearded Vulture eggshells, with the typical orange coloration due to the iron oxide applied by the adult birds to their breast feathers.
(D) Several goat horns found in the same ancient nest.
(E) Typical solid Bearded Vulture droppings accumulated in their ancient nests.
Photographs: Sergio Couto. – “The Bearded Vulture as an accumulator of historical remains: Insights for future ecological and biocultural studies”
From feeding ecology to historical ethnographic conditions
Between 2008 and 2014, Sergio Couto and his team visited over 50 Bearded Vultures nests around Southern Spain and collected materials from 12 of them. Collectively, these nests contained 2117 bone remains, residues of their inhabitants´ meals over time, 43 eggshell fragments, memories of all the breeding seasons they hosted, and 226 anthropogenic remains probably used as nest building materials. The bones are mainly ungulate bones, a testament of the dietary habits of the species since medieval times. Among the collection of human memorabilia, scientists had some interesting findings: a crossbow bolt, a basketry fragment dated around the 18th century, a sandal made of grass cord dated around the late 13th century, and a sheep leather. These anthropogenic elements are of immense ethnographic value. They attest the creation of artifacts made using plant fibres in the Mediterranean region of the Iberian Peninsula already 12,000 years ago.
One nest, many environmental information
The analysis of the content of each nest can provide important information on the abundance and distribution of wild vertebrates in the area, and how animal-human interactions developed over time. In addition, toxicological screenings of the eggshells offer the unique opportunity to reveal the presence of toxins, extracting evidence related to pesticides and other contaminants. Lastly, the nests themselves are a testament of Bearded Vulture presence, marking potential reintroduction areas for the species where it has not been seen in a century, and help guiding future conservation efforts.
(A) Part of an esparto grass slingshot.
(B) A detail of a crossbow bolt and its wooden lance.
(C) Agobía (Sierra Nevada, Granada), a rough footwear made of several species of grass and twigs, C-14 dated at 674 ± 22 years Before Present (ETH-138982). Agobías typically lasted for a few days of wear and were continuously repaired and replaced by hand by the wearer.
(D) A basketry fragment C-14 dated at 151 ± 22 years Before Present (ETH-138980).
(E) A piece of sheep leather C-14 dated at 651 ± 22 years Before Present (ETH-138981) with red lines drawn, and (F) a piece of fabric. Scale bars are in centimeters.
Photographs: Sergio Couto (A, B, D, and F) and Lucía Agudo Pérez (C and E). – “The Bearded Vulture as an accumulator of historical remains: Insights for future ecological and biocultural studies”
Bearded vultures as bioindicators
The content of Bearded Vulture nests is not only a matter of feeding and nesting habits. The study highlights Bearded Vultures as exceptional bioindicators. Their nests contain precious data on animal distribution, environmental conditions, pollution, and human activities and cultural changes though time. The careful nesting site selection, and the habit of reusing the same nest over time, make Bearded Vultures not only guardians of mountain biodiversity, but also unintentional archivists of human history. This study opens the possibility to explore coevolution between ecosystems and human practices, offering a new approach that combines vulture conservation, ethnobiology and archaeology. In conclusion, by protecting Bearded vultures and their habitats, we also safeguard invaluable records of our shared past.
