A recent news item in the New York Times science section read: “Misguided Leaders Don’t Lead Pigeons Off Course.” Given this election season, I delved beyond the short summary in the paper.
A University of Oxford team did the research. (Recent British politics have been crazy, too.) Here are the details. As with humans, there’s a hierarchy in homing pigeon flocks. When setting out, homeward bound, established leaders set the course.
Researchers observed several flocks to determine the leaders. Next they manipulated daylight in the leaders’ roost boxes to throw off their internal clocks.
As pigeons navigate largely by the sun, their sense of direction was confused when the roost box doors were opened as signal to head home.
The sun was in the wrong place! Disoriented, the leaders headed the wrong way.
In response to the misdirection, flock dynamics shifted and the intelligence of the group took over to steer the way home.
Researchers couldn’t determine if the leader sensed it was off course and dropped back to let others take over; or whether the flock determined the misdirection and collectively “stepped up” to take over.
Did the leader step aside, knowing it wasn’t up to the job? Or did the “grass roots” take action and save the day? Here’s how the fuller New York Times online report ended: “Either way the pigeons figured out what the correct direction was. Sadly, these are pigeons, and this has nothing to do with politics.” Even a natural history account can’t escape election politics.
Pigeons have been studied before, and not as benignly as above, as researchers have attempted to learn more about bird navigation.
That birds navigate visually by sun, moon and stars has been known for some time. One key experiment placed first-year indigo buntings in a planetarium with a rotating dome of stars. As the dome turned above them, the birds maintained their orientation away from the North Star. It was fall, and time for the young birds to head south for the first time.
Songbirds are nocturnal migrants and they do just that — fixing on the North Star as the other stars shift around that one true point.
Clear, starlit nights this time of year deliver newcomers to backyards, just passing through, southward bound.
Besides sun and stars, birds orient by Earth’s magnetic fields. Observations of caged birds hopping energetically on the south side of their cage in fall suggested directional intelligence separate from visual cues of the North Star.
When magnetic fields around the cages were altered, the birds shifted the orientation of their hopping accordingly.
Not just homing pigeons can find their way home. Numerous experiments have packed various bird species up, transported them great distances, and documented their return to their nesting territories.
Magnetic reckoning studies became more sophisticated—and pigeons were enlisted once again.
Recent experiments determined that neurons in the pigeon’s brain are activated as magnetic fields are artificially shifted around the birds.
Shifting directions activated different neurons, sending messages to orient east or north-north west, and so on.
That’s one piece of the puzzle, but where’s the compass? What receptor detects magnetic fields and transmits that information to the neurons? For some time it was thought to be magnetite in a pigeon’s bill. It’s best not to think about experiments that debunked that theory.
A few years ago attention turned to a bird’s inner ear as receptor, followed soon by research reporting the discovery of microscopic “iron balls” in what were described as thinly sliced neurons in a pigeon’s inner ear.
Apparently the receptors exist in every bird species surveyed so far, although it was pigeons that led the way.
Progress made on one question, leads to another really big one: Where’s the map? The birds transported hundreds of miles east or west of their home territory, far from any familiar north-south migration route, knew how to get home. Even seabirds that don’t fly over land managed to figure out an overwater route home that was a lot different than an “as the crow flies” direct route.
Very cool. And not just birds have internal GPS systems.
Favorite article title in my research effort: “Magnetic Orientation and Navigation in Marine Turtles, Lobsters, and Molluscs: Concepts and Conundrums.” My one homing pigeon story has to do with a tawny-colored bird that became quite at home at our daughter’s chicken coop, moving in with the hens.
I took a photo of “Homer” to get the serial number from his leg band so I could notify the homing pigeon world of a missing member.
I didn’t hear back. Birding pal Rich Frechette pointed out that very likely its owner had no interest in a pigeon that couldn’t find its way home.
Of course.
Backyard Birder by Francie Von Mertens appears every other week in the Monadnock Ledger-Transcript.