Parrots use their beaks to swing like monkeys

Pink-faced lovebirds are attractive and compact parrots. They're also not afraid to use their heads – literally – to get around an awkward situation.

“They are incredibly intelligent animals, they are good problem solvers, and that also extends to the way they move,” said Edwin Dickinson, a biomechanist at the New York Institute of Technology.

The parrots demonstrated their talents to Dr. Dickinson and his colleagues recently in the laboratory as they moved around in roosts that became smaller and smaller. When the bar became thin enough, the birds gave up trying to balance with their feet. Instead, they moved under the wire, hanging by their beaks and swinging their legs and bodies, almost like a monkey swinging from tree to tree in the forest. While parrot owners may have noticed such beak swinging in their pets, scientists set out to understand the forces behind it, which they discovered described Wednesday in the journal Royal Society Open Science.

This is not the first time parrots have been observed using their heads to navigate. In a previous study, the same team gave lovebirds a surface to walk across, making it progressively steeper. As the angle of the runway increased, the birds began to use their beaks to grasp and aid in climbing. The researchers went so far as to suggest that the animals essentially walk with three limbs.

In their latest study, the team placed a sensor that measures forces in the birds' path, and observed that the head does more than just stabilize the movement when the birds move their feet along the wire.

“In terms of limb loading, they're able to support their entire body weight using just their heads, which is pretty remarkable,” said Melody Young, a biomechanist at the New York Institute of Technology and author of the book. the study.

This movement is “highly unusual,” said Pauline Provigne, an evolutionary biologist at the National Museum of Natural History in Paris. The bird uses the beak for feeding, and it also plays a role in calls and songs. “But for mobility, it is relatively rare,” she said.

The movement pattern that comes with using the head as a third limb requires parrots to coordinate their beaks and legs. “We tend to see birds as just wings, because flight is so wonderful,” Dr. Provini said. But birds have evolved a variety of ways to use their legs: walking, jumping, paddling, and perching. She noted that their heads and necks are very strong.

The swing of the beak resembles the movement of monkeys. So scientists coined the term “beaking,” a play on “convergence,” the term that refers to primate penis movements. The researchers compared the swinging of parrots' beaks to the movement of a gibbon — whose swings bounce with momentum — and the upside-down walk of sloths. The team found that the parrots' swings fall in the middle. Like gibbons, spider monkeys, and humans, which use their arms, birds can suspend their entire weight on the beak, which acts as a limb. But they do not recover as much energy as primates in their swings.

It's not clear how widespread the beak is in wild birds, but researchers hope that scientists in the field will be able to monitor the beak swing. “It is likely that parrots around the world have been doing or capable of doing something similar since time immemorial,” Dr Dickinson said.

Other birds may use beak swings, said Diego Sustaita, an organismal biologist at California State University San Marcos who was not involved in this work. For example, beyond parrots, researchers may want to look at other tree-dwelling creatures, such as voles or trogons. Comparing species can provide hints about the evolution of behavior.

The new research also contains a warning for scientists who might make assumptions about how extinct animals moved by studying their anatomy, said Michael Granatowski, whose lab at the New York Institute of Technology examines parrot movements.

Biologists usually assume that form predicts function. But the swing of the beak shows that an animal's anatomy sometimes works in a way that scientists can't predict from its shape. People do not usually think about moving with the neck or mouth, mainly using systems that control feeding. But scientists extract clues about the movements of ancient creatures from their fossils all the time.

“If we were trying to predict what animals did from their bones alone, we would likely miss entirely new forms of movement or things that animals might have done that we never imagined,” Dr. Granatowski said.