The leader of a pigeon flock usually flies in front—until it’s demoted by its flockmates. Photo: Zsuzsa Ákos

Science

In Homing Pigeon Flocks, Bad Bosses Quickly Get Demoted

New research shows how the birds keep flock leaders with bad information from throwing them off course.

From the outside, a flock of homing pigeons doesn't look very organized. Unlike a synchronized starling flock, it moves more like a tortured cloud, constantly shifting and roiling in chaotic disarray. But on the inside, the flock is a complex system of individual birds all working towards one goal: getting home.

Each bird navigates with an internal compass calibrated to the sun, and it’s this precise compass that gives the birds their name and millennia-spanning reputation for navigational excellence. Homing pigeons shared the results of the first Olympic Games across the ancient Greek city states, served as messengers and spies in war, and carried mail for Genghis Khan in the 12th century and New Zealanders as recently as a century ago.

But what works for an individual pigeon becomes information overload when they’re in a group. If each bird follows the magnetism of its own compass, there isn’t much of a flock. To hold together, flocks navigate collectively based on a hierarchy of leadership where each bird contributes to decisions to some degree, increasing in influence as it climbs the power ladder. The leader, typically positioned at the front of the flock, holds the most sway and is supposed to keep the group on course.

Blind loyalty may work fine when the leader knows what it’s doing, but that’s not always the case. “Intuitively you’d think it would make sense for everyone to let the most competent individuals lead,” says Isobel Watts, a biologist who studies animal navigation at the University of Oxford. However, “previous work has shown that leadership does not necessarily correlate with competence," she says. Rather, it tends to be the fastest flyers that sit at the top of the hierarchy.

If a leader has bad intel or is otherwise incompetent, a flock could quickly get lost. So Watts wondered: How do flocks deal with bad leaders? A pigeon has never led a military coup or started a petition to hold a recall election, as far we know. But as Watts found, in a new study published today in Biology Letters, the birds have their own ways of keeping their leaders from leading them astray.

With her colleagues, Watts raised eight flocks of five homing pigeons each and fitted the birds with GPS loggers to track their movements. After training them to return to their loft at the university’s field research station from a nearby village, she “misinformed” the birds by breaking their internal compasses.

Pigeons use the sun to navigate by keeping track of its changing position throughout the day. So by placing the pigeons in a light-tight room and exposing them to periods of light and darkness that were a few hours off from actual sunrise and sunset, the scientists shifted the birds’ internal clocks to an artificial day-night—essentially giving them jetlag, Watts says.

“Once released, they misinterpret the sun’s position,” she says. “This will cause them to assume a course that is shifted compared to the direction they actually want to go in.”

Flexible flock hierarchy lets homing pigeons collectively navigate home despite incompetent leaders. Photo: Zsuzsa Ákos

Watts used this technique, called clock-shifting, to test the birds’ navigational abilities in two experiments of two flights each on their pre-trained route (in addition to a pair of normal flights for comparison). In the first experiment, all the birds in each flock carried busted compasses. When she released them at the village, they made it home—but after a roundabout journey to get there. The birds deviated widely from their typical route, looping back and forth along the path. In one case, a flock meandered off-course and headed back to the release site before getting its bearings.

However, when the leaders alone were jetlagged, the flocks stayed the course and took a pretty direct route back home from the release site. That’s because the leaders didn’t do much leading, Watts says. Rather, they were demoted. By tracking the birds’ positions within the flock, the researchers determined that when flock leaders alone had miscalibrated compasses, they lost their places at the top of the hierarchy. Five were demoted during their first clock-shifted flight, and all eight during the second flight. 

“Since the rest of the birds still had good information, they could perform just as well as they had during training,” Watts says, and the misinformed leaders weren’t able to drive them off course.

The researchers speculate that a lousy flock leader could lose its power in two ways. Its followers could recognize that something is off—that the leader’s decisions conflict too much with their own information—and filter out the leader’s bad information in a respectful rebellion. Or a leader could step down voluntarily when it notices a mismatch between its information and that of the other birds. “It starts paying more attention to its flockmates, and by definition this results in it becoming a follower,” Watts says.

She isn’t sure which one of these mechanisms is at play, and may try to untangle that in the future. She also wants try a similar experiment with the pigeon version of a “nightmare boss”—a leader that has bad information, but is certain that they’re right. A phenomenon any person who's ever held a job is likely all too familiar with but, unlike pigeons, has no power over.   

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