Triumph displays inform eavesdropping little blue penguins of new dominance asymmetries

► Triumph displays are postconflict signals performed by winners following fights. ► We evaluated the impact of triumph calls on social eavesdroppers in little blue penguins. ► Male penguins displayed higher heart rates in response to a winner's call. ► They were also less likely to vocally threaten winners than losers. ► By advertising victories, winners may establish a “reputation” for winning fights.