Most archaeologists are human—most, though not all, apparently. According to new analysis in Ecology, bearded man (Beard grows) have served an archaeological role in southern Spain for hundreds of years, accumulating man-made objects and hiding them in their nests.
Analysis shows that these nests are thus “natural museums“, filled with artifacts that can provide important information about the past. In fact, the material contained in these nests can tell us everything about the ecology of a species., as well as its historical environment, including access to materials created by man hundreds of years ago.
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These avian archaeologists have been collecting strange things
The bearded vulture is now endangered, but centuries ago the species was widespread in the mountains of Europe and, in particular, in the mountains of Iberia. There, vultures built their nests on the cliff sides, hiding sticks and other materials in crevices and caves among the mountain peaks. The sheltered conditions of these caves meant that their nests remained throughout, surviving for decades and centuries, and being reused by generation after generation of birds.
Bearded vultures' nests, often located in caves or sheltered rock ledges, provide ideal microclimatic conditions to preserve both the bone remains they bring to feed their chicks and the material for nest construction.
(Image credit: Sergio Couto)
The nests themselves were built primarily from twigs and grass, mixed with other items including bones, feathers and fur, as well as fabric, rope and other man-made materials. So, what kind of oddities are built inside these nests and how long have they been hidden there?
To find out, the authors of the analysis decided to study objects in historical bearded vulture nests, assessing the birds' accumulation of natural and man-made artifacts and their reuse of their shelters over time. In the case of southern Spain, an area where the species disappeared approximately 130 to 70 years ago, the team found about 50 nests and examined 12 of them, finding a total of 2,483 objects.
In all 12 nests, 2,117 bone fragments and 43 eggshell fragments were found, which allows us to judge the birds' diet and reproduction. At the same time, 226 objects of anthropogenic origin are described, including 129 objects made of fabric, 72 objects of leather, 25 objects of esparto grass and 11 objects of hair. While natural objects indicated the presence of all kinds of animals in southern Spain, including a small number of bird and mammal species, human-made artifacts provided a glimpse into the material traditions that were present throughout the Iberian Peninsula.
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A source for future scientific research?
The objects themselves were identified in layers, much like artifacts at an archaeological site separated by layers or layers of sediment. This stratigraphic approach, combined with carbon-14 (C-14) analysis, allowed the team to pinpoint the age of the nests and begin to piece together the time frame of their habitat, thereby providing important information about the birds' ecological and historical environment.
Among the handicrafts found in bearded vulture nests, scientists found part of an esparto sling, a piece of wickerwork, a piece of sheepskin with red lines painted on it, and, surprisingly, a crossbow bolt that the bird may have used as nesting material or collected from prey.
(Image credit: Photos: Sergio Couto (A, B, D and F) and Lucia Agudo Perez (C and E))
For example, a sandal from one of the nests was dated to about 675 years ago, and a piece of painted sheepskin from the same nest was dated to about 25 years later. Other items included a sling belt, a fragment of a basket, a strip of cloth and a crossbow bolt, the weaving fragment being approximately 150 years old.
The age of the objects suggests that some of the nests have been occupied by vultures for decades, and the state of preservation of the objects indicates that the nests themselves, nestled in the rock, acted as a kind of natural shield, maintaining stable temperature and humidity, or a “microclimate,” that helped natural and man-made objects survive.
According to the team, the results highlight that the bearded vulture served as an important battery, collecting items of ecological and historical importance that could change our perception of the past hundreds of years later. Although the bird itself is not visible in southern Spain today, it played an amazing role in preserving Iberia's past by collecting objects and preserving them for study by future scientists.
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