It's well-established that primates and a handful of mammal species will reconcile when a mutually beneficial relationship has been ruptured. This kind of behavior had never been observed in birds - until now. In a study of adolescent ravens (not pair-bonded), these researchers found that not only will they repair the relationship, but they will be less likely to act aggressively toward each other in the future.
While these researchers speculate that this might be a behavior that exists in others birds, as well, I would not be so willing to jump toward that conclusion. Ravens (and crows, as well as some species of parrots) are NOT at all like other birds. Both cognitively and interpersonally, they are unique - as far as we know right now - among bird species.
Reconciliation, a post-conflict affiliative interaction between former opponents, is an important mechanism for reducing the costs of aggressive conflict in primates and some other mammals as it may repair the opponents' relationship and reduce post-conflict distress. Opponents who share a valuable relationship are expected to be more likely to reconcile as for such partners the benefits of relationship repair should outweigh the risk of renewed aggression. In birds, however, post-conflict behavior has thus far been marked by an apparent absence of reconciliation, suggested to result either from differing avian and mammalian strategies or because birds may not share valuable relationships with partners with whom they engage in aggressive conflict. Here, we demonstrate the occurrence of reconciliation in a group of captive subadult ravens (Corvus corax) and show that it is more likely to occur after conflicts between partners who share a valuable relationship. Furthermore, former opponents were less likely to engage in renewed aggression following reconciliation, suggesting that reconciliation repairs damage caused to their relationship by the preceding conflict. Our findings suggest not only that primate-like valuable relationships exist outside the pair bond in birds, but that such partners may employ the same mechanisms in birds as in primates to ensure that the benefits afforded by their relationships are maintained even when conflicts of interest escalate into aggression. These results provide further support for a convergent evolution of social strategies in avian and mammalian species.
Citation: Fraser, ON, Bugnyar, T. (2011). Ravens Reconcile after Aggressive Conflicts with Valuable Partners. PLoS ONE 6(3): e18118. doi:10.1371/journal.pone.0018118
The whole article is available online at the link above, and as a PDF download.