[Tweeters] Motion in Birds

[Diane Yorgason-Quinn via Tweeters]

The Italian study StarFlag has been working on this for a long time with 3-D photography, etc.  It's SEVEN that is the number of birds that each flock member keeps track of, and the number is thought to be the maximum number that their brains can handle.  Of local interest is that an offshoot of StarFlag, consisting of the COBBS group from ISC in Rome (Istituto dei sistemi Complessi), along with Portland State University and the U.S. Army Corps of Engineers, is working now on 3 years of study of Vaux's Swifts entering northwest chimneys from their overhead swirls, yielding over a million 3-D images, and the paper may soon be published.  The chimneys were selected with the aid of Larry Schwitters of Vaux's Happening.

Overview: http://murmuration.weebly.com/starflag-project.html


Diane Yorgason-Quinn
Gig Harbor, WA
Avosetta at hotmail.com
________________________________
From: Tweeters <tweeters-bounces at mailman11.u.washington.edu> on behalf of Mark Walton via Tweeters <tweeters at u.washington.edu>
Sent: Monday, July 29, 2024 9:28 AM
To: Robert O'Brien <baro at pdx.edu>
Cc: tweeters <tweeters at u.washington.edu>
Subject: Re: [Tweeters] Motion in Birds

My immediate thought/speculation about the starling murmuration thing is that it sounds like something that might be a result of the fact that it takes any brain a certain amount of time to process visual information from the eyes, determine the appropriate movements to react to what was seen, and then compute the exact amount of contraction needed for each muscle to execute the planned action. I would guess that visuo-motor reaction times in birds are probably MUCH faster than they are in humans but it certainly wouldn't be instantaneous. If each starling is reacting to the movements of the most nearby starlings then, for a large flock, these very small processing delays would add up to something that would be noticeable to us. The end result would be that birds that are far away from each other in the flock make direction changes at different times, resulting in the flock rapidly changing shape.

I'm thinking it might be the same kind of phenomenon as when you're driving in heavy traffic and you're stopped at a red light with 20 cars in front of you. The light turns green and it feels like it takes forever for the car in front of you to get moving - even though every single driver is reacting fairly quickly. It's just that the visuo-motor processing time ends up being rather long when the small processing delays for 20 people get added up.

In a flock of birds I would guess that it would also serve the important function of possibly confusing a predator. So, maybe it's a case of the laws of physics and chemistry imposing delays that happen to benefit the birds?

As an interesting aside, there are some situations in which these processing delays pose a computational problem, such as when you're using your eyes to follow a moving object. If you're always 200 ms late in reacting you won't be able to do it, so the brain employs predictive algorithms in these situations to compensate for its own processing delays.

Mark

Ar Luan 29 Iúil 2024 ag 08:51, scríobh Robert O'Brien via Tweeters <tweeters at u.washington.edu<mailto:tweeters at u.washington.edu>>:
Thanks to Mark for that fascinating explanation of head (non) motion.  I have another question for him that may OR MAY NOT be apropos.
In recent years there have been discussions about how flocks of various birds (starlings, sandpipers, etc.)  manage their motions in formation.
I recall one study a few years back that determined that Starlings manage to do their maneuvers so that each one was surrounded by 6 other Starlings.
I'm a chemist so I recognize that 'structure' as hexagonal close-packing.  That is, if you have objects (marbles, golf balls, molecules, etc) all the same size then they have
the highest density if each object is surrounded by 6 others.
(This gets into crystalline structure such that all sorts of other structures are possible, especially if objects are of different sizes.  Sodium chloride (table salt) has a cubic structure due to the difference in size between the small positive Sodium (+) ion and the larger negative Chloride (-) ion.).  Etc.

But chemistry aside, in flight all the Starlings are moving, but the 6 birds around each (except for their joint directed motion) are basically stationary.  And then?   Some bird(s) change direction, which is echoed at a delayed time by the entire flock.   This is often stated to be a means of avoiding predators (hawks)  but I believe Starlings do that even when no predators are present.  Maybe just for fun?.  (Turkey Vultures seem to sail around for extended periods, no synchrony, just for fun).

Any comments on this Mark?  Thanks

Bob OBrien   Portland

P.S.   I won't bother to dig out photos, but I have noticed that Sanderlings running on the beach back and forth with the waves, often also run in formation, so that all their legs in a photograph are in sync with each other.    And speaking of the beach, there are fish schools that behave like Starlings, etc. etc.  Finis!


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