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How Giraffes Neck



>On a related topic:
>I wonder  how giraffes protect their brains from whiplash during their own
>neck duels?
>
>Leslie Gertsch
>Research Assistant Professor
>etc.
>

This is not really a complete answer, but the following is taken from RD
Estes, "The Behavior Guide to African Mammals" at p. 205:

"The challenge to a duel begins with an apparently nonchalant approach. When
close, the challenger raises his head and stands in the erect posture facing
his opponent.  If the other responds in kind, they then stalk forward
stiff-leggedly and stand parallel, or they may march in step with necks
extended horizontally, looking straight ahead. At low intensity, they
proceed to rub heads and necks gently together, and may lean heavily against
each other with ears flapping and rub shoulders or flanks - probably
assessing their comparative weight and strength. Sometimes they pause and
gaze into the distance. The prospective winner can be predicted by noting
which male holds himself more erect.  At higher intensity, the contestants
aim blows at rump, flanks, or neck, often standing
in reverse-parallel. Preparatory to giving or receiving blows, a giraffe
braces himself by straddling his forelegs; then he draws his  neck sideways
and swings upward and backward over his shoulder to strike his opponent with 
the parietal horns, thereby concentrating the blow in a small area.  But
blows seldom land solidly, for each does his best to avoid being hit by
moving his neck away at the last moment, meanwhile getting ready to return
the blow.  Movement and countermovement appear rhythmical and synchronized,
imparting the sinuous grace of a stylized dance.  There may be long pauses
between blows when  the animals stand motionless.  Sometimes they lift their
noses as if trying to look taller or to snatch a mouthful of leaves
(displacement feeding).

"The force of a solid blow is literally staggering.  The heavier the skull
and the wider the arc of the swing, the harder a giraffe can hit-hence the
advantage of age, height, and weight. Mature bulls know their place in the
hierarchy and normally avoid confrontations, even when an estrous female is
at stake. A serious fight is apt 
to be brief but violent and involve a stranger with the top male in the
local hierarchy.  After a few heavy blows, 
one gives up and runs away. In one case a bull was knocked senseless and lay
stretched on the ground for 
20 minutes before recovering."

Estes also notes, contrary to an incorrect assumption I made in an earlier
post (sorry) that the horns certainly are used in necking (p. 202) and the
skull is adapted for combat (this may be part of your answer):

"Male horn growth continues through a unique process whereby bone of dermal
(skin) origin is deposited over the whole surface of the skull except where
muscles attach.  Apart from the parietal and median horns, bone accumulates
as knobs at the base of the skull, over the eyes, and on the nose.
Gradually the male's head becomes a massive knobbed club which is used to
gain the dominance that spells reproductive success.  The skull of a
fifteen-year-old bull may be 7 kg heavier than that of a bull half his age."

This is not only interesting, it gives me a chance to play with my new
scanner/OCR!

Besides: this suggests an actual hypothesis: if sauropods actually used
their heads and necks for combat as giraffes do, and assuming that
increasing age and size moved them upwards in whatever dominance heirarchy
they may have had, you might expect to see, as in giraffes, increasing
deposition of bone on the skull with increasing size.  Do larger sauropod
skulls in fact have proportionately more bone than smaller skulls of the
same species?
         
         
         
         
--
Ronald I. Orenstein                           Phone: (905) 820-7886 (home)
International Wildlife Coalition              Fax/Modem: (905) 569-0116 (home)
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