A disabled kea parrot is the alpha male of his circus

How physical disability affects social rank remains poorly understood1,2. Contest theory predicts that asymmetries decide fights: the larger, better-armed competitor typically prevails3. Bruce, an endangered kea parrot (Nestor notabilis) missing his entire upper beak, has previously innovated to survive - using pebbles as self-care tools4. Here, we report that he has also innovated to thrive in his captive environment. Bruce is the alpha male of his circus (the collective noun for a group of kea): despite being the only disabled bird in his group, he was undefeated in dominance interactions with his male peers, exhibited the lowest stress hormone metabolites, had priority access to feeding stations, received the only allopreening directed toward a non-mate (Figures 1 and S1), and achieved this without allies. His weapon? A novel beak jousting technique (Figure S1 and Video S1) that turned his disability into dominance. These results show how behavioural innovation can dramatically reverse the consequences of disability in animals.