A scientific team from different Spanish research institutes found that vultures have different diet patterns depending on the place where they breed, regardless of the available resources
This indicates that they have different "tastes" by cultural transmission among individuals of the same population. Until now, it was believed that vultures were opportunistic species that consumed any type of carrion without indiscriminately.
People's eating habits are not born, they are made. Our food tastes and diet are strongly influenced by where we are born and the social group in which we are raised. However, this cultural transmission is not just a human characteristic: vultures also show this cultural patterning. A new study published in the journal Proceedings of the Royal Society concludes that vultures have also different food preferences depending on the place or group they belong to. The work led by the researcher Eneko Arrondo is the result of a broad collaboration between different Spanish centres and universities, including the University of Granada, the Doñana Biological Station – CSIC, the Miguel Hernández University, the University of Seville and the University of Alicante.
Previous studies on the vultures' diet have focused on the population as a whole than on each individuals. However, in this work, the researchers wanted to go further and have analysed for the first time the diet of vultures on an individual scale. To do so, they carried out an exhaustive field work in the Iberian Peninsula and combined GPS tracking of 30 griffon vultures captured in Las Bardenas Reales in Navarra and 35, captured in the Sierra de Cazorla in Jaen.
Thanks to the accelerometer integrated in the GPS device, the researchers could find out where each of the tagged individual had eaten. A team of ten people went through four thousand of these places analysing what the vultures had eaten in each one of them. With this data, they reconstructed their diet. "We observed, for example, that males prefer resources more closely linked to humans, mainly intensive livestock and garbage, while females are more likely to feed on less predictable resources, such as hunting remains or extensive livestock", explains the researcher Eneko Arrondo, from the University of Granada.
One of the hypothesis to explain this behaviour is that males have a more confident attitude in humanized landscapes, close to human populations, with more infraestructures or highly disturbed environments, such as garbage dumps. "In other words, males would more often dare to eat in more dangerous places. On the contrary, females would be les confident and more catious", says José Antonio Donázar, Research Proffessor at the Doñana Biological Station – CSIC. The team hopes to corroborate this hypothesis in the future with new studies.
These differences were also evident between the two populations in Navarra and Jaen. The individuals captured in Bardenas fed mainly on the remains of intensive farms, which are very abundant in the area, while those captured in Cazorla preferred hunting remains and extensive livestock, which are the main resources in their roosting area. "But the most surprising thing was that, when we analysed what the vultures of both populations ate when they shared feeding resources in the Extremadura dehesas, we observed that the individuals retained their dietary preferences. This pattern was maintained even when food availability was the same for all individuals", says Arrondo. "This shows that vultures acquire food preferences thanks to the cultural transmission between individuals of the same population".
These results are described by the team as "fascinating". Until now, it was believed that vultures were opportunistic species that consumed any type of carrion indiscriminately. "We had no previous evidences of this behaviour, but the advance in GPS technology is allowing us to make an exhaustive tracking of each individual and helping us to better understand the ecology of these species, which are more complex than previously thought", explains José Antonio Donázar. Thanks to this work, a new door opened in the trophic ecology of these important scavengers, which provide essential ecosystem services in rural environments.
The study was funded by Project P18RT1321 of the regional government of Andalusia (Junta de Andalucía) and the Community of Bardenas Reales de Navarra.
Eneko Arrondo, Esther Sebastián-González, Marcos Moleón, Zebensui Morales-Reyes, José María Gil-Sánchez, Ainara Cortés-Avizanda, Olga Ceballos, José Antonio Donázar and José Antonio Sánchez-Zapata. Vulture culture: dietary specialization of an oblígate scavenger. Royal Society Publishing. https://doi.org/10.6084/m9.figshare.c.6622035