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. 2020 Feb 12;10:2430. doi: 10.1038/s41598-020-59387-4

Table 2.

Description of the variables used in the study of agonistic behavior and interactions among European vultures during carrion exploitation in Spain including the different categories into which these variables were divided.

Variable Categories Description
Age class* Adult Birds showing definitive adult plumage, according to48
Juvenile Birds with plumage traits corresponding to their first and second calendar year
Subadult Birds with plumage traits corresponding to their third and fourth calendar year (up to sixth calendar year in the bearded vulture)
Type of agonistic interaction Fight/attack Aggression or attempted aggression by using beak, claws and/or opening the wings to occupy the place occupied by another individual
Displacement Charge/push to move another individual and occupy its place, without the help of beak, claws or open wings
Stealing Removal of a piece of food from an individual which had already acquired it, either from its beak or claws, or by forcing regurgitation
Result of the interaction Success The individual observed managed to displace the other individual from its place, or to steal food from it
Failure The individual observed failed to displace the other individual from its place, or failed to steal food from it by being repelled or avoided
Not clear/indifference No change of place or stealing from one individual by another (aggressor or victim) or the result is not clear
Role in the interaction Aggressor Individual starting and carrying out competitive interactions on another individual
Victim Individual initially receiving and suffering the interaction (fight/attack, displacement, stealing)

All of the variables were considered as response variables except age class, which was explanatory.

*For the cinereous vulture we joined the adult and subadult age classes in the analyses due to the variability in plumage traits after the juvenile phase48.