In 2021, a disabled parrot named Bruce made headlines worldwide for creating his own prosthetic beak. He didn’t stop there: Scientists reported on Monday that Bruce has now become the alpha male of his group.
And he did it by learning to joust.
The new research, published in Current Biology, is an important addition to a small but growing number of observations that demonstrate just how resilient animals with disabilities can be, said Alice Auersperg, a cognitive biologist at the University of Veterinary Medicine Vienna who was not involved in the study.
“The link between innovation and disability in animals is important and completely understudied,” she said.
Bruce is a 13-year-old kea, a species found only in New Zealand. These seagull-size parrots live together in groups, known as circuses, that can number in the dozens.
Keas were viewed as pests until the past few decades, because they sometimes attack sheep when their regular food supply runs short. As recently as the 1980s, the New Zealand government paid bounties for dead keas, helping to drive down their numbers to fewer than 5,000.
The bounties are gone, but keas still face grave threats. The curious birds get injured trying to steal food from rat traps, for example. That’s what scientists suspect happened to Bruce when he was a youngster. When they discovered him in the wild, his entire top beak had been snapped off.
Bruce’s injury amounted to a severe disability. Keas use their long, hooked top beaks to preen, keeping their plumage clean and free of dangerous parasites. The birds also dig with their beaks for seeds and other food on the forest floor.
“Losing it would likely make basic survival in the wild very difficult,” said Dr. Auersperg.
The researchers brought Bruce to the Willowbank Wildlife Reserve, where he joined a dozen other keas living in captivity. As he grew up, scientists visited his circus to study the birds’ intelligence.
The keas proved to be curious problem-solvers. And they seemed to have fun along the way.
“They’re so playful all the time,” said Alex Taylor, the director of the Animal Minds Lab at Universitat Autònoma de Barcelona. “They want to play with your shoelaces, they want to steal your pens.”
Dr. Taylor once watched two keas land on a floating log. Together, they figured out how to turn it into a seesaw. Fun.
Bruce eagerly tried to join the scientists’ experiments. But without a top beak, he struggled with simple tasks like pulling a string.
But the parrot found another way to impress. In 2021, the researchers noticed that he regularly picked up a pebble, holding it between his tongue and lower beak and then pushing it through his plumage.
After watching this puzzling routine a number of times, the researchers realized that Bruce had invented a new way to clean his feathers.
It was a trick Bruce apparently came up with on his own. None of the other keas at the reserve used pebbles to preen, and the behavior had never been observed before in the species.
Last year, Bruce delivered a second surprise.
Male keas fight for dominance. Those who lose fall to the bottom of the circus hierarchy, and they experience stress as a result. The alpha male ends up with the lowest stress levels.
To measure the stress among the nine male keas at the reserve, Dr. Taylor and his colleagues analyzed certain hormones in their blood. Much to their surprise, the male kea with the lowest levels was Bruce.
“We never expected him to be right at the top of the males,” said Alexander Grabham, a zoologist at the University of Canterbury and an author of the study.
The surprise prompted Dr. Grabham and his colleagues to look more closely. Reviewing videos, they discovered that Bruce had risen to the top with a new style of kea combat.
Male keas typically bite one another around the neck. Bruce can’t bite; instead, he has learned to joust. He rushes his opponents and slams his lower beak into their bodies.
Jousting proved a winning strategy. Bruce consistently won his fights, and the other males deferred to him. One perk of becoming the alpha male: Bruce got to visit the bird feeders first.
“Nobody ever tried to jump him or displace him,” Dr. Grabham said.
After enjoying a meal, Bruce permits lower-ranked males to preen his feathers and clean his bottom beak. “And when Bruce is done, he’ll give a kick or a little joust to say, ‘Right, that’s it, I’m done,’” said Dr. Grabham. “That to me is a sign of dominance.”
There are some questions about Bruce’s ascension that will be impossible to answer. For instance, Dr. Grabham and his colleagues can’t say when Bruce figured out how to joust and become the new alpha.
“We haven’t been tracking his dominance and stress over the last 12 years to know the journey that he’s been on,” Dr. Taylor said. “We weren’t really looking for it, so we didn’t really join the dots.”
Sarah Turner, a primatologist at Concordia University in Montreal who was not involved in the study, said research on other species supports the idea that animals with disabilities sometimes come up with innovative ways to stay alive, and to thrive.
In Dr. Turner’s own research, she has observed that Japanese macaques with deformed hands will learn how to walk bipedally instead of on all fours. And males with disabilities seem to fit easily into the social hierarchy, sometimes reaching the top ranks.
Humans are responsible for many of the disabilities in animals, Dr. Turner said — from congenital malformations caused by pollution to injuries caused by traps, electrocution and road accidents.
Scientists need to learn more about how animals adapt to disability, she added, as humans put more pressure on the animal kingdom: “The world is a living lab now.”
Carl Zimmer covers news about science for The Times and writes the Origins column.
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