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鈥檚 this precise compass that gives the birds their name and . Homing pigeons shared the results of the first Olympic Games across the ancient Greek city states, served as , 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鈥檙e in a group. If each bird follows the magnetism of its own compass, there isn鈥檛 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鈥檚 doing, but that鈥檚 not always the case. 鈥淚ntuitively you鈥檇 think it would make sense for everyone to let the most competent individuals lead,鈥 says , a biologist who studies animal navigation at the University of Oxford. However, 鈥減revious work has shown that leadership does not necessarily correlate with competence," she says. Rather, it tends to be the 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 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鈥檚 field research station from a nearby village, she 鈥渕isinformed鈥 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鈥 internal clocks to an artificial day-night鈥攅ssentially giving them jetlag, Watts says.
鈥淥nce released, they misinterpret the sun鈥檚 position,鈥 she says. 鈥淭his will cause them to assume a course that is shifted compared to the direction they actually want to go in.鈥
Watts used this technique, called clock-shifting, to test the birds鈥 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鈥攂ut 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鈥檚 because the leaders didn鈥檛 do much leading, Watts says. Rather, they were demoted. By tracking the birds鈥 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.
鈥淪ince the rest of the birds still had good information, they could perform just as well as they had during training,鈥 Watts says, and the misinformed leaders weren鈥檛 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鈥攖hat the leader鈥檚 decisions conflict too much with their own information鈥攁nd filter out the leader鈥檚 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. 鈥淚t starts paying more attention to its flockmates, and by definition this results in it becoming a follower,鈥 Watts says.
She isn鈥檛 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 鈥渘ightmare boss鈥濃攁 leader that has bad information, but is certain that they鈥檙e right. A phenomenon any person who's ever held a job is likely all too familiar with but, unlike pigeons, has no power over.