Path: utzoo!attcan!uunet!samsung!zaphod.mps.ohio-state.edu!ub!rutgers!att!cbnewsm!rsl
From: rsl@cbnewsm.att.com (randolph.little)
Newsgroups: rec.birds
Subject: Re: Parallax vs receptor saturation (was Re: Head Jerking)
Summary: Raptor head bobbing - multiple advantages?
Message-ID: <1990Aug7.121102.3740@cbnewsm.att.com>
Date: 7 Aug 90 12:11:02 GMT
References: <1990Jul28.033019.5059@ddsw1.MCS.COM> <63474@oliveb.atc.olivetti.com> <122642@kean.ucs.mun.ca>
Organization: AT&T Bell Laboratories
Lines: 18




David Graham writes:
>I like the theory recently advanced here that it's a question of
>saturation vs refreshing of receptors in order to provide optimum
>resolution of incoming predators.  But what about raptors?  ....
Recall that hawks and owls are exceptional among birds in that
they DO have binocular vision, giving them the opportunity to
use parallax clues to perceive depth.  David's point is good.  Let's not
rule out either receptor refreshment or depth enhancement as "causes"
for head bobbing in perched raptors.  Both factors may apply.
	Randolph S. Ltle  (randolph.little\@att.com)
	#UUCP: bonasa!rsl or mtuxo!rsl or attmail!rsl
	#DDD: 908-658-2640
	#USMail: AT&T C02-34D64
	55 Corporate Drive
	Bridgewater, NJ 08807-6991