Ravens are renowned for their intelligence and sophisticated social behaviour. But a new study has revealed a previously unknown strategy among the social-climbing corvids.
Ravens attempt to prevent others forming alliances that might lead to them becoming future competitors.
In raven society, individuals may gain power by forming coalitions. “The hierarchical structure among the ravens is highly dependent on their bonding status,” explains research team member Dr Jorg Massen from the University of Vienna’s Department of Cognitive Biology.
Within this hierarchy, established 'bonded' birds are further up the social ladder than those in the process of making bonds, known as 'loosely bonded' birds. At the bottom of the social hierarchy are birds with no specific bonds, these are known as 'nonbonded' individuals.
Dr Massen and colleagues from the University of Vienna wanted to investigate whether ravens could “act upon their social knowledge and selectively intervene” in bonding attempts among other birds.
Well-bonded ravens might preserve their high status by intervening in affiliative interactions between ravens that are about to form a bond
They found that ravens with existing social bonds initiated most interventions of bonding attempts in others. And those trying to forge new bonds (the loosely bonded birds) were most often the targets of the intervention.
The scientists also found that nonbonded birds at the bottom of the hierarchy were less likely to be to be interrupted if they interacted with others, possibly because they posed less threat to birds higher up the social ladder.
“Well-bonded ravens might preserve their high status by intervening in affiliative interactions between ravens that are about to form a bond,” the researchers write in the report published in the journal Current Biology.
“So far, this is the first description of this behaviour being so specific that it can be described as a social strategy,” Dr Massen told BBC Earth. “However, it might just be that we were also only the first to look at it.”
The team observed a group of around 300 wild ravens (Corvus corax) in the Austrian Alps for six months, and recorded 106 interventions by individuals when others were engaged in affiliative activities such as mutual preening.
Divide and rule
Birds’ interventions were most successful when they placed themselves in the middle of the pair attempting to bond.
However, intervening birds risked aggression from interrupted pairs.
Other parties in such a system might try to divide a coalition by for example highlighting specific differences among the two parties
The scientists did not observe any immediate advantages for the intervening individuals, although in their report they speculate these birds might benefit in the long term by preventing others from becoming close allies. But Dr Massen says more long-term data is needed to confirm this.
The social strategies used by ravens are not dissimilar to those seen in political parties of the human world, Dr Massen suggests. “I think the divide and rule tactic is a common tactic among politicians, especially in a multi-party political system where 'power' [or] a majority relies on a coalition,” he says.
“Other parties in such a system might try to divide a coalition by for example highlighting specific differences among the two parties… Although of course slightly more sophisticated, the basics are the same.”
Dr Massen and colleagues predict the strategy of intervening in bonding attempts observed in ravens is likely to occur in other species that form strong social bonds in the struggle for power, such as other corvids, primates, dolphins and hyenas.