Table 2.
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.