Abstract
Dominance hierarchies typically emerge in systems where group members regularly encounter and compete for resources. In birds, the ‘open’ and dynamic structure of foraging groups may prevent the emergence of structured hierarchies, although this assumption have hardly been tested. We report on agonistic data for ravens Corvus corax, collected over two 18-month periods for 183 marked individuals of a wild (fluid) population and 51 birds from six captive (stable) groups. We show that the dominance structure (steep and transitive) in wild foraging groups is strikingly similar to that found in captivity. In the wild, we found that higher ranks are mainly occupied by males, older and more aggressive individuals that also tend to receive fewer aggressions. Exploring the mechanisms sustaining the wild dominance structure, we confirmed that males are more aggressive than females and, with age, tend to receive fewer aggressions than females. Males that are about to leave the foraging groups for some months are less aggressive than newcomers or locals, while newcomers are specifically targeted by aggressions in their first year (as juveniles). Taken together, our results indicate that the socially dynamic conditions ravens face during foraging do not hinder, but provide opportunities for, using (advanced) social cognition.This article is part of the theme issue ‘The centennial of the pecking order: current state and future prospects for the study of dominance hierarchies’.
Highlights
Competition for resources and reproduction is a key challenge for animals, and in particular gregarious species [1]
Individuals can, for instance, base their decisions on whether to aggress or submit to a conspecific on the physical appearance of the opponent and/or spatial association patterns
Corvus corax, are an interesting model species to study dominance under ‘complex’ dynamic social conditions: on one hand their foraging groups are characterized by moderate to high fission–fusion dynamics, on the other hand they are structured by age, breeding status and differentiated relationships
Summary
Competition for resources and reproduction is a key challenge for animals, and in particular gregarious species [1]. Corvus corax, are an interesting model species to study dominance under ‘complex’ dynamic social conditions: on one hand their foraging groups are characterized by moderate to high fission–fusion dynamics, on the other hand they are structured by age, breeding status and differentiated relationships. Braun & Bugnyar [37] argued that physical appearance (sex and age) and/or spatial associations (as typical for bonded birds) may serve as reliable cues for ravens to broadly categorize individuals into being ‘dominant’ or ‘subordinate’ under dynamic free-flight conditions They proposed that individuals could follow the rules-of-thumb that: males dominate females (owing to their weight, around 1250 g for males versus 1100 g for females; see [41]), older birds dominate younger birds (owing to their weight and/or experience) and bonded birds dominate nonbonded birds (owing to social support). We used our two wild datasets to test these predictions
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
