Viewpoint: Why did Neanderthals capture birds?
It is now almost three years since our team published evidence of the regular exploitation of birds (raptors and corvids) by Neanderthals.
The conventional wisdom had been that Neanderthals did not have the capacities or technology that allowed them to capture fast-moving prey.
Only our own ancestors had these abilities, among them the skills to catch birds. Equipped with a package of skills, which included the exploitation of marine resources, our ancestors spread across the world from their African home following coastlines.
In 2011, an Italian team had published evidence of Neanderthal exploitation of raptors and corvids for the use of feathers.
Raptors, of course, are otherwise known as birds of prey, and corvids are the group that includes crows, magpies and ravens, as well as other less celebrated species.
Our own work expanded the range of species and numbers and, critically, showed that Neanderthals had exploited a range of raptor and corvid species over a long period. This meant that the activity was not casual or sporadic.
In March of this year, a Croatian team reported tell-tale marks on the talons of White-tailed Eagles, associated with Neanderthal activity in the site of Krapina and claimed that this was evidence of jewellery-making. A similar report on the talons of these and also Golden Eagles by Neanderthals at the site of Combe Grenal in France had previously been published in 2012.
Put together we now have evidence of Neanderthal activity on raptors and corvids, for the purposes of ornamentation, from four European sites.
No fewer than nine raptor and three corvid species have now been associated, some in more than one location. We have been asking ourselves if these species share features that would make them particularly vulnerable or attractive to the Neanderthals. Remarkably, most of the species are birds which are attracted to carrion. Which are they?
Three of the four European vultures are implicated: Griffon Vulture, Cinereous Vulture and Lammergeier depend almost entirely on the carcasses of large mammals and bones of all three have been found with the tell-tale cuts made by Neanderthal tools.
The two European kites - Red and Black Kites - are well known scavengers of carrion, offal and human rubbish. What may come as a surprise is the presence of Golden Eagle and White-tailed Eagle, large predators that may seem unreachable to a Neanderthal.
It is not really surprising when we see that even today the two giants regularly scavenge to supplement live prey during the winter months. The corvids are, like the kites, well-known opportunists and scavengers. So there is a pattern here and it implicates scavenging birds. The absence of other raptors, species known not to be regular scavengers, enhances the picture even further.
All this suggests that the Neanderthals, well-known as ambush hunters of large mammals, could have been lying in wait when the scavengers came down to a carcass.
We may never know how they got these large and powerful birds but we can suggest that it may not have been as difficult as we might imagine. We have been studying these large eagles, vultures, kites and corvids at feeding stations in Spain and in Sweden.
The provisioning of carcasses is a regular practice that aids in the survival of these vulnerable species, as shown in a recent publication. The vultures and some corvids and kites scavenge the year round but the eagles do so almost entirely in the winter as do the choughs (two species of corvids strongly associated with the Neanderthals).
This may suggest that the Neanderthals were practising the activity mainly during the winter months. That would certainly account for the absence of Europe's fourth vulture - the Egyptian Vulture - from our list: in winter this migratory vulture is in sub-Saharan Africa where there were no Neanderthals.
In the course of our work we have come across some unexpected situations that have left us in awe. At one site in the Aragonese Pyrenees, naturalist Manuel Aguilera has been feeding vultures for over thirty years.
The vultures are so used to him that they recognise him and land right by him in expectation of the food he provides. These large Griffon Vultures - one of the Neanderthal favourites - literally feed from his hand! Somewhere else, in the Catalan Pyrenees, vultures have learnt to recognise the vehicle of their food provider, naturalist Jordi Canut.
They gather by the hundreds and impatiently await the food delivery, jostling for position, on the ground. It seems that being in pole position overrides any fear of humans. These present-day natural experiments show us that catching large scavenging birds may not have been that difficult at all for the intelligent and resourceful Neanderthals and that the established anthropological idea that birds were difficult to catch needs rapid revision.
Redefining the Neanderthals is the theme of this year's Calpe Conference to be held in Gibraltar between the 24th and 27th September. Leading international researchers will gather this year to review all the latest evidence of the Neanderthals, from genetics to the behaviour. And the subject of birds of prey is likely to take up a big chunk of one of the sessions as researchers who have published evidence from Gibraltar join forces with those from Italy and Croatia to give us a fresh perspective on this very new subject.
Stewart and Clive Finlayson are naturalists based in the Gibraltar Museum. Stewart is currently studying Neanderthal-bird interactions for a PhD with Anglia Ruskin University. Clive has been directing excavations in Gibraltar since 1991 and has published widely on the Neanderthals. Both are keen nature photographers and the photos illustrating this feature are their own.