Barbara J. King

Friday Animal Blog

Pigeons wearing backpacks!

April 9, 2010

Pigeons wearing backpacks! This phrase uttered by a science reporter on NPR’s program All Things Considered caught my fancy. The reporter described how scientists are studying the collective movements of birds in flight. Retrieving the relevant article from yesterday’s issue of the British journal Nature, I read ‘Hierarchical Group Dynamics in Pigeon Flocks,’ written by four scientists from Hungary and Britain. There was no photograph of a backpack-sporting pigeon, but it’s exciting stuff nonetheless.

The researchers, led by Mate Nagy at a university in Budapest, tested the details of in-flight behavior of homing pigeons by equipping them with lightweight GPS devices -- in the mini-backpacks noted on NPR. The questions at the heart of the research were these: How do birds make quick decisions in flight? How can we understand "the seemingly instantaneous changes in a flock’s direction of motion, the abrupt splitting of a flock, or a synchronized landing," all done on "a very short timescale"? Are decisions that enable these directional changes made according to sets of rules?

It turns out -- for these specific homing pigeons anyway -- flight leaders emerge within a flock and influence the movement of other birds. Leader birds position themselves near the flock’s front: other pigeons tend to watch and copy the movements of these "alpha birds" in a kind of leader-follower arrangement. The researchers could even tell that a pigeon uses the left eye preferentially in this situation: “The more time a bird spent behind a particular partner, the more likely it was to be flying to that partner’s right.” Given brain lateralization, using the left eye means that the visual input goes to the right hemisphere— intriguing, because scientists have known that birds’ right hemispheres are used for recognition of individuals.

A pigeon flock, then, has a left-right as well as a front-back gradient. And the pigeons organize themselves into a hierarchy. On one final point the data are less than crystal clear, but Nagy et al. find hints that "navigational efficiency" (measured via solo homing flights) is the determining factor in who becomes a flight leader.

When we look up and see sky-wheeling birds, we may tend to assume one bird’s flying position is interchangeable with another’s. But not so: this new research points not only to bird smartness but also to bird individuality. Who’s who matters in Bird World (at least to the extent that other species’ patterns mirror the pigeons’, a hypothesis that still needs to be tested.)

Here in southern Virginia, the sounds of songbirds sweeten my spring days. And because bird-flight is as poetic as bird-song is musical, I’ll close on a poetic note—with the first stanza of Robert Louis Stevenson’s poem ‘As in their Flight the Birds of Song’.

As in their flight the birds of song
Halt here and there in sweet and sunny dales,
But halt not overlong;
The time one rural song to sing
They pause; then following bounteous gales
Steer forward on the wing:
Sun-servers they, from first to last,
Upon the sun they wait
To ride the sailing blast.

Selected Works

Why are animals so irresistible to us? Why do we live with and care so deeply about them? From the famous "art caves" of ice-age Europe, to the ancient villages where animals were first domesticated, to stories of apes, whales, dogs, and cats doing fascinating things today, King weaves together a scenario about the animal-human bond that encompasses our past, present and future.
Can scientists discover a prehistory of religion just as they have traced the evolution of technology, language, and art? What does compassion in chimpanzees, or burial patterns in our human ancestors and Neanderthals, tell us about the origins of religion? In Evolving God, named a Top Ten Religion Book for 2007 by the American Library Association, Barbara King explores these questions.
How do chimpanzees, bonobos, and gorillas-- the African apes -- communicate using body postures and gestures? Using her many years of experience studying these apes, Barbara King answers this question in a book that offers a new perspective on the evolution of language.