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A Straight Dope Classic from Cecil's storehouse of human knowledge
13-Apr-1979
Dear Cecil:
Can you in your infinite yet magnanimous wisdom explain something that's been troubling
me for years? When pigeons bob their heads as they walk is it because their legs are
connected to their necks or what? --Dennis A., Highland Park, Illinois
Dear Dennis:
Of course not. As any fool can see, a pigeon's legs are connected to its body--and it's a
good thing, because the pigeon would look mighty funny if it were assembled according to
the offhand anatomy you describe.
Basically the pigeon's back-and-forth head motion--not exactly a bob--helps it keep its
balance when walking. The pigeon's legs are located pretty far astern, and if it kept its
head forward all the time it would probably tip over. This would expose the pigeon to the
ridicule of the community. Instead, what it does is move its chest forward in time with
one leg, and its head forward in time with the other leg. Thus some weight is always
trailing a little abaft the port beam, as we say. Many fowl have similarly peculiar gaits,
because they cannot afford orthopedic shoes.
GRATUITOUS INSULTS FROM THE STEAMING MILLIONS
Dear Cecil:
You dunderhead, where'd you dig up that story about pigeons bobbing their heads to
maintain balance? Any text of ornithology (Pettingill's, for example) will tell you
pigeons, like most birds, have eyes on the sides of their heads, their vision's basically
monocular, and they bob their heads for depth perception. Birds with front-faced eyes,
like owls, have binocular vision, and, like people, don't have to bob their heads.
Straight dope, indeed! -- Paul G., Chicago
Dear Paul:
Listen, you chump, it happens that I have had an intimate association with pigeons since
my earliest days and I know everything there is to know about them, or pretty nearly,
anyway. My father used to send me out to feed the damn pigeons in his damn pigeon loft all
the time, and I want to know who you are going to believe, some stupid internationally
famous ornithologist or me, veteran pigeon feeder.
I'll admit this Pettingill fellow may have something with this depth perception business,
but it is my undying conviction that balance has as much to do with it. It is well known
that pigeons, along with most other birds, have enormous fields of vision--they can see
340 degrees around without moving, owing to the peculiar construction of the eyeball and
the way the eyes are placed in the head. The peripheral vision of each eye is so great
that the two visual fields overlap, giving the pigeon a binocular field of 24 degrees when
it looks straight ahead. So if the pigeon is walking straight toward, say, a tasty piece
of corn, it does not need to bob its head to maintain depth perception.
On the other hand, like all bipedal creatures, its ability to maintain balance is a
delicate thing, and since its "arms" are occupied being wings, it is not
unreasonable to suppose that the back-and-forth motion of the head helps maintain balance.
So there. See if I ever answer any of your questions again, punk.
FURTHER ENLIGHTENMENT ON THE GREAT PIGEON HEAD-BOBBING CONTROVERSY
Dear Cecil:
The diffuse speculation on the function of pigeon head movements recently aired in your
column demands comment. Unfortunately, both you and your steaming ornithological detractor
err grievously. The bobbing actually takes place to preserve monocular acuity. Here's how
it works, swine.
For an animal with side-mounted eyes, forward movements result in parallax shifts
(apparent motion of near objects relative to distant objects). Now, vertebrate eyes--and
retinas--work much better with completely stationary images. So what happens is that the
bird's body walks on while the head is temporarily left behind to stabilize the image. The
head is then jerked forward at the start of the next step.
Owls and humans, by contrast, have front-facing eyes, and thus, no parallax problem while
walking. Heavy-headed creatures with side-mounted eyes (pigs, cows), for which the avian
solution is impractical, apparently were dumb to start with and have grown to enjoy
parallax shifts. If the aforementioned blather continues, maybe you and your critic along
with Pettingrill should consider having your eyes remounted to match your wits. --Martin
S., Chicago
Dear Martin:
It's Pettingill, not Pettingrill, my son. Try not to get so excited about these things. In
light of the fact that we now have three separate theories on why pigeons bob their heads,
it is apparent that the definitive answer to this question continues to elude the great
minds of this century. Unless there are any pigeons out there who wish to contribute to
the discussion, we will leave this issue to future generations to decide.
ABSOLUTELY THE LAST THING YOU WILL EVER HAVE TO READ ON THIS RIDICULOUS SUBJECT
Dear Cecil:
I read your column in the discarded alternative newspapers--of which, I might add, there
is no small supply--that blow my way across the pavement. About the pigeon
controversy--i.e., why pigeons jerk their heads when they walk--the answer is really quite
simple. We do it because it feels good. --Walter Pigeon, Equitable Plaza, Chicago
--CECIL ADAMS
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