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From: phz@cadence.com (Pete Zakel)
Newsgroups: rec.birds
Subject: re: HEAD JERKING OF WALKING BIRDS
Message-ID: <9007262151.AA29536@cds709.noble.com>
Date: 26 Jul 90 21:51:21 GMT
Sender: daemon@ucbvax.BERKELEY.EDU
Lines: 9

I always assumed birds jerked their heads so that most of the time their
heads (and therefor eyes) were stationary with regard to surroundings for
the majority of the time.  When I've watched birds closely, they jerk
faster when they walk faster, and during the non-jerking portion the head
remained stationary w/r/t the surroundings.  I assumed this was to make
seeing easier.

-Pete Zakel
 (phz@cadence.com or ..!{hpda,versatc,apollo,ucbcad,uunet}!cadence!phz)