Despite lacking a half-beak, Bruce is the boss of his Kea circus
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A parrot missing half of its beak is the best bird in New Zealand’s Willowbank Wildlife Reserve. The parrot, named Bruce, win every fight with other kea parrots and gets priority access to food, researchers report April 20 in Current biology. These results challenge assumptions about how disability influences dominance in animal societies and show that innovative behaviors can counterbalance physical disadvantage.
Willowbank kea parrots live in a large aviary with trees and a stream. When visitors stop, they often don’t notice the birds sleeping among the leaves. But when they spot Bruce, they always make the same comment, says Alex Grabham, a behavioral ecologist at the University of Canterbury in Christchurch. “Look at this poor bird.”
Visitors’ pity is misguided, says Grabham.
He and his colleagues described Bruce’s social interactions with his flock (technically called a circus, reflecting the kea’s playful nature). Like other parrots, kea have a social hierarchy, determined by dominance interactions such as fighting, screaming, or feather fluffing.
Grabham’s team recorded 162 physical dominance interactions between the nine men in Bruce’s circus over four weeks. Bruce won all 36 of his interactions. He was undoubtedly the best Kea.
And he is the first disabled animal to achieve high status within a group without the support of an able-bodied ally. (Faben, an alpha male chimpanzee living in Tanzania’s Gombe National Park, lost his highest rank after polio paralyzed his arm. He later rose to beta male status after perfecting a charging technique to fend off rivals and forming an alliance with his brother, who replaced him as alpha male.)
An unusual fighting technique was also the key to Bruce’s success. While other kea tended to rely solely on kicks to fend off other birds, Bruce supplemented his kicks with a unique jousting technique that exploited his exposed lower beak. Grabham’s team filmed another 109 agonistic encounters between Bruce and other birds. During these, Bruce kicked slightly more than he played, but the latter attack was much more effective, pushing his opponent back 73% of the time, compared to just 48% when he kicked.
Bruce’s high social position has its advantages. Other male kea preen Bruce, helping him clean the parts of his beak he can’t reach. This behavior is very unusual among kea, which normally only preen on their partners. The lower another male’s rank, the more likely he was to preen Bruce. This behavior imitates hierarchical grooming observed in chimpanzees.
The lower-ranking birds also gave Bruce a first share of food. The circus’ food was distributed primarily among four central feeders. Over the four weeks that Grabham’s team analyzed Bruce, he ate first from these feeders 83 percent of the time. For four days, the other birds gave Bruce 15 minutes of uninterrupted alone time with the four feeders before eating his scraps.
In many animal societies, top status comes at a price. “An animal that occupies a high position in the dominance hierarchy must constantly defend that position,” says Amalia Bastos, a comparative psychologist at the University of St Andrews in Scotland, who previously studied Bruce. Alpha male baboonsfor example, show higher levels of stress metabolites called glucocorticoids.
Grabham’s team measured glucocorticoids in the birds’ droppings. Turns out Bruce was the coolest kea in the circus. It’s not yet clear why, but Grabham believes that Bruce is so dominant that the other kea don’t pose any serious challenges to his throne. “He knows he won’t be followed, beaten, intimidated or chased,” Grabham says.
It is unclear whether Bruce would have thrived in a wild circus to the same degree as he did at Willowbank. Bastos points out that with his damaged beak, Bruce might have difficulty eating tougher foods during the winter. Additionally, the hierarchy of most circus kea is fluid, as birds join and leave groups throughout the year. For now, in Willowbank’s strict hierarchy, Bruce is the boss.
This is not the first study that shows that Bruce is capable of innovation. In 2021, researchers reported on its self-smoothing technique. He uses stones to clean his feathers. “Bruce has demonstrated twice that being different is not necessarily disadvantageous,” Bastos says.
