By Charlotte Reid 
The unique discovery of artefacts and remains in cliffs in southern Britain opens up new horizons for studying medieval daily life. How these refuges for birds of prey can become unexpected archives of natural and human history, according to National Geographic.
The discovery of a medieval sandal, woven more than six centuries ago inside the nest of a white-headed vulture on the cliffs of southern Britain, has revealed the potential of these structures as veritable natural archives capable of preserving fragments of human and ecological history.
According to National Geographic, more than 200 human artefacts and animal remains were found alongside the sandal, providing a unique opportunity to glimpse the interaction between humans and wildlife over the centuries.
This discovery was the result of a series of expeditions conducted between 2008 and 2014. A team led by Antony Margalida, an ecologist from the British Institute of Ecology, descended from the cliffs to reach a dozen nests of bearded white-headed seabirds.
Among the items found, a sandal known as an agobia stands out. It was made of grass and twigs and is estimated to be between 652 and 696 years old. This shoe has been preserved thanks to the cool, dry microclimate of the cave, where vultures have protected it among branches and other objects for generations.
Unique conservation activity in the nests of bearded vultures
The nests of this species create exceptional conditions for the preservation of very ancient materials. The bearded vulture, the only vulture that specialises in eating bones, lives in mountainous areas and builds its nests in secluded corners of rocks.
Each time these vultures occupy a nest, they add new materials: twigs, sheep’s wool to insulate the eggs, and the remains of their prey, such as bones and parts of goat carcasses. Margalida compared these nests to a natural history museum, as the cave environment ensures that the items the birds place in the nest are preserved for centuries.
National Geographic reports that even after this species disappeared from southern Britain in the last century, ancient nests remain as evidence of its presence.
An examination of 12 nests revealed an astonishing number of items: 86 hooves, more than 2,100 bones and fragments of eggshells from ancient chicks. Artefacts associated with humans were also found, including textiles and tools.
Of particular interest are a slingshot made of esparto grass and a crossbow bolt, the presence of which may be related either to the construction of the nest or to the fact that they were stuck in the prey. Using radiocarbon analysis, researchers determined that the esparto grass sandals are about 675 years old, and the fragment of a woven basket is about 150 years old.
A natural archive of scientific value
An astonishing variety of objects have been found in the nests of white-headed vultures, including bones, eggshells, textiles and human tools, which help to trace the evolution of fauna and flora.
The scientific interest in these finds goes beyond simple archaeological curiosity. As Margalida explained to National Geographic, studying the materials preserved in the nests can provide key information about human history, the vultures’ diet and environmental changes in the region.
For example, toxicological analysis of eggshells can indicate past exposure to pesticides, while the identification of animal and plant species among the remains allows us to track changes in fauna and flora over time.
Furthermore, dating the materials helps us understand how long vultures have been using the same nesting sites.
Toxicological analysis of eggshells has revealed past pesticide exposure in vulture nests.
Long-term reuse of nests is not unique to the bald eagle. Trisha Miller, a wildlife biologist and executive director of Conservation Science Global, Inc., told National Geographic that many birds of prey maintain their nests for centuries, accumulating layers of material from different eras.
There are documented cases, such as a golden eagle’s nest that was six metres deep due to the accumulation of material over generations.
Human objects in nests: a mystery
It is not always clear why vultures place human objects in their nests. Margalida told National Geographic about the discovery of a T-shirt in a modern nest, which vultures may have used instead of sheep’s wool. Other finds, such as a crossbow bolt, raise questions about their origin and purpose.
Studying artefacts found in vulture nests may provide new insights into the historical relationship between birds and humans.
Miller, researching nests in New Jersey, has found everything from rope to plastic and wonders whether the birds are attracted to foreign materials or simply use them as decoration.
Drawing an analogy with a medieval British sandal, Miller reported finding a crocodile-skin boot in one of these nests.
Margalida’s team still has numerous objects awaiting study and funding . She also assured National Geographic that these materials will open up new perspectives on the history of vultures and the people who lived alongside them.