January 15, 2013 | David F. Coppedge

Pigeon Aerobatics Exceed Expectations

A pigeon in the plaza may seem pretty ordinary, but it’s a highly skilled stunt bird.

In “Aerial Acrobats: Pigeons Whoosh Through Tight Space,” Elizabeth Pennisi wrote for Science Now about a presentation at the Society for Integrative and Comparative Biology.  “The [pigeons] are doing a lot of things aerodynamically and flightwise that we haven’t realized,” said one biomechanics expert.

With high-speed cameras, researchers from Harvard filmed pigeons coaxed to fly and perch on the other side of an obstacle resembling jail bars. They started the birds with 30-centimeter-apart bars, then narrowed it down to 11 centimeters – the bird’s body width plus a centimeter on each side.  The birds navigated the course with ease.

In wider gaps, the pigeons tend to hold their wings up high—pausing briefly at the top of the wing stroke—as they pass through the bars, Williams reported at the meeting. In this way, the birds can quickly do a down stroke once they get through to help stay airborne. But when the gap is too narrow, the birds instead fold their wings, holding them close to the chest, and glide through. Thus, they are less likely to be knocked off course should they strike a bar.

Another Harvard researcher examined how pigeons prepare for a turn.  High-speed images showed that they make use of a stabilizing reflex, first turning their head.  The rest of the body follows, banking and turning to allow a steady gaze.

Nice as this is to know, human designers now have some new data to imitate:

With studies like these two, “We are starting to get at the strategies used to [ensure] robustness, flexibility, and stability” in biological movements, Sponberg says. “Understanding these strategies is really critical for any applied stuff,” such as robots that can control themselves in flight. These autonomous flyers would be useful for exploring unknown terrain or doing reconnaissance for search-and-rescue operations after earthquakes or other natural disasters, Ros says. Toward that end, he and Williams’ collaborators are incorporating these results to help build pathfinding computer programs that will direct future aerial robots.

In another article on birds, Science Daily reported that a multinational team created a 3-D image of a zebra finch’s voicebox, the syrinx (analogous to the human larynx).  The colorful diagram shows multiple interacting parts.

The syrinx, located at the point where the trachea splits in two to send air to the lungs, is unique to birds and performs the same function as vocal cords in humans. Birds can have such a complete control over the syrinx, with sub-millisecond precision, that in some cases they are even able to mimic human speech.

The model is able to “show in detail the delicate balance between strength, and lightness of bones and cartilage required to support and alter the vibrating membranes of the syrinx at superfast speeds.”

See?  There are talking animals on earth.

Pretty good trick to sail right through bars only 11 centimeters (4.3″) apart.  Now consider that bats can do this trick in the dark, using sonar.

This is exemplary of so many things in the living world: the more you examine them, the more amazing they become.  Never take a pigeon for granted.  Our best designers would like to do what they do.  But don’t minimize your own gifts, either; some birds can mimic human speech, but none of them have been found to compose poetry, translate a foreign language in real time, or hold a two-way conversation with relatives on the other side of the world.


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