observations of complex phenomena while in Mexico

Posted by Phil Henshaw-2 on
URL: http://friam.383.s1.nabble.com/Meeting-at-St-John-s-tomorrow-tp523290p523293.html

I just love watching birds and can see you do too!  One behavior I like
especially is the flocking of birds at dusk.  I don't know the details
of where they're headed or even why they'd eventually roost by the
hundreds in a single tree, but the way they soar in great weaving clouds
that are pulled apart as small groups leave and draw out others, to then
reform again and continue the dance, is just amazing.   I've watched the
behavior with many species, city, country, different places.   It always
comes clear to me that what they're doing is some kind of negotiation.
You have to ask, what's the sense of their being in such a big group in
the first place, and then why go through such extended gyrations, maybe
30-40 circles before deciding who sits where on what tree...  

For another one, what do you think is going on with the apparent global
end of the great Canadian Geese migration?  When I was a kid it was like
clockwork, twice a year we'd see these beautiful high altitude
formations of mysteriously honking great birds heading a couple thousand
miles north or south.  Now it seems they just quit! and hang out in the
same parks and golf courses year round.   That seems a very odd way to
end an ancient habit of having two homes, shifting, for me, from being
this remote beauty to an annoying local pest in just 30 years.  That's
not evolution.

I think the idea that these fascinating patterns have some simple
explanation other than the behavior of the birds themselves is
questionable.   We stumble into thinking that things are caused by the
effect they have, which is backwards of course.  That reasoning was
popularized by, and somewhat reasonable for, genetic evolution where
you're dealing with a record keeping system that's fairly reliable and
can record some kinds of effects for the future instances of a behavior.
For how birds socialize I think something else is needed.   To me many
things like these are better explained by looking at the opportunities
being taken rather than the necessities being imposed, but that's a
longer story.

Anyway, my guess on why the Mazatlan frigatebirds went into set V
formations after a period of gliding and the ones in Cancun didn't is
that they were different birds, with different social habits.   It could
be that the ones you saw in Mazatlan were a community with strong
leaders and the ones in Cancun weren't, or something.  Clearly it's a
whole lot easier to marvel at them than really understand what's
happening.


Phil Henshaw                       ????.?? ? `?.????
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680 Ft. Washington Ave
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e-mail: pfh at synapse9.com          
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> -----Original Message-----
> From: friam-bounces at redfish.com
> [mailto:friam-bounces at redfish.com] On Behalf Of Hugh Trenchard
> Sent: Friday, January 05, 2007 9:42 PM
> To: The Friday Morning Applied Complexity Coffee Group
> Cc: Gottfried Mayer
> Subject: [FRIAM] observations of complex phenomena while in Mexico
>
>
> I am a lurker on this listserv and find many of the discussions here
> interesting and valuable.  Recently I was in Mexico and
> noticed a couple of
> interesting complex phenomena I thought I would share with this group.
>
> The first relates to frigatebird formations and ties in with
> observations of
> these birds I made last year.  Last year, when in Mazatlan, I
> noticed that
> frigatebirds often hover and glide for several minutes at a
> time without
> flapping and that they tend to glide in disorderd
> configurations until they
> spontaneously undergo a phase change (it seems to me) when
> they align in vee
> formations - still gliding nonetheless.  These are fantastic
> sights to see,
> since the birds seem to hang in the air in these vee
> formations without
> passing across the sky at the relatively high speeds of
> geese, for example.
>
> This year, in Cancun, I noticed frigatebirds gliding in disordered
> configurations and, waiting patiently for the phase change, I was
> disappointed when these changes did not occur.  I wondered if I was
> imagining the alignments I saw last year in Mazatlan, but
> fairly certain I
> wasn't, I speculate why the phase changes did not occur among
> the birds I
> saw in Cancun.  Firstly it's possible the frigatebird colonies on the
> Caribbean side of Mexico simply don't undergo these
> formations, being a
> slightly different sub-species or what have you.  Perhaps,
> but I hypothesize
> that the wind speeds are the primary factor in determining
> whether formation
> phase changes occur.
>
> In Mazatlan last year in late Sept/early October, the wind
> speeds were low,
> I recall.  In Cancun, wind speeds were significantly higher.  
> I suggest that
> gliding in vee formations can only occur between a certain
> range of wind
> speed - if wind speed is too low, the birds cannot glide at
> all; if too
> high, they can glide, but they cannot align in vee
> formations.  The critical
> range allows frigate birds to draft when gliding behind another while
> maintaining position, but above the range the drafting effect
> is too high
> and the birds get "sucked" through - or tend to fall, it
> looked to me - the
> low pressure areas and cannot hold their positions.
>
> Drafting ordinarily has the effect of saving energy (a la
> cyclists in a
> peloton), but if birds are gliding and already saving
> substantial energy by
> not flapping their wings, I wondered whether any significant
> energy savings
> benefit can be derived by aligning in vee formations while
> gliding.  At
> first I thought not, but gliding inevitably requires some
> energy - small
> muscle coordination and positional adjustments - not as
> costly as flapping
> wings, but some energy is required.  When frigatebirds form vees, I
> hypothesize there is in fact significant energy savings for
> those birds in
> drafting positions - small muscle contractions for positional
> adjustments
> may be reduced, and birds in these formations will expend
> less energy. They
> would not, I suggest, align in these ways if it were not for
> some energy
> savings benefit.
>
> Because frigatebirds do not generate the higher air pressure
> behind which to
> draft, such as geese do, or cyclists do, or fish in water do
> by propelling
> themselves through the medium (air or water), I suggest this
> form of energy
> savings constitutes a third type of "drafting".  The other is energy
> reduction by huddling, such as penguins undergo.  So I
> suggest three types
> of drafting occurrences:
>
>         I       Occurs when system components generate
> effective air or
> liquid pressure as they propel themselves through the medium;
> eg. cyclist
> pelotons, fish schools, geese in vees;
>
>         II      Occurs when system components remain
> stationery and air or
> liquid pressure is generated externally; eg frigatebirds in
> vees while
> gliding and remaining more or less positionally stable, and
> possibly some
> types of fish (here I suggest this may occur in fish swimming
> upstream, such
> as salmon, which may hold themselves in a stationery position
> against the
> flow of the water - I haven't specifically observed any
> interesting drafting
> formations as a result, although I have watched salmon swim
> upstream and
> speculate drafting formations do occur)
>
>         III     Occurs when system components remain stationery and
> environment temperature drops; eg. penguin huddles
>
> Type I exhibit phase changes from disordered states to
> ordered states and
> back again through hysteresis loops. For cyclists, when
> peloton speeds are
> higher than a critical speed/drafting threshold, disorder in
> the peloton
> occurs.  In a peloton, density is generally higher at low
> speeds and density
> decreases as speeds increase.  At a relatively high threshold
> speed, a
> peloton loses cohesiveness entirely.  To resume cohesion,
> peloton speeds
> must fall to a lower threshold to resume cohesive formations
> (I've observed
> and documented this).  The loop is clockwise (speed on Y
> axis, density/order
> on X) , but is the inverse of vehicle traffic hysteresis, for
> example, where
> density increases as speed decreases (note that drafting is
> not a factor in
> traffic).
>
> For frigatebirds, because order increases as windspeed increases to a
> threshold range, above which disorder occurs, wind speeds
> must only drop to
> within the critical range for order to occur again. As a result the
> hysteresis loop may not exist or is not as evident. I
> tentatively speculate
> this windspeed range is approximately equivalent to the magnitude of
> drafting benefit derived when birds are in drafting
> formations; similarly
> the height of the hysteresis loop in drafting cyclists is
> related to the
> drafting benefit derived (but may not precisely match it).
>
> So drafting parameter seems to represent a constant that
> manifests itself in
> related but different ways.  For example, in Type 1
> situations, drafting
> parameter indicates the magnitude of the hysteresis loop; in
> Type II where
> there is no hysteresis, drafting parameter indicates the
> magnitude of the
> critical range of speeds within which certain formations
> occur. Drafting
> parameter is thus also a general principle underlying the
> self-organized
> complex behaviour of a number of different systems.
>
> For Type III (penguin huddles), density/order increases as
> temperature drops
> (requiring greater energy output to remain warm, so a decrease in
> temperature is equivalent to an increase in speed in Type I
> situations);
> density/order decreases as temperature increases to some
> threshold, after
> which there is no huddle cohesion. Presumably at some very
> cold temperature
> the huddle cannot generate enough heat and disintegrates by penguins
> freezing to death. In the direction of temperature increase,
> the hysteresis
> loop occurs when disorder occurs at a critical temperature,
> but must fall to
> some lower threshold temperature for the huddle to occur again.
>
> In any event there is a lot more analysis to be made, and I
> have more to say
> even now, but here are a few observations.  Basically, my
> point is that
> through my frigatebird observations, I've identified a third type of
> drafting situation.  I had already identified the peloton
> (which is obvious
> and well documented) and huddle situations (which is not as
> obvious and not
> well documented).  _____________
>
> The second, slightly less rigourous observation I made when
> in Cancun was a
> clustering effect among cabs. In Cancun, and likely many
> parts of Mexico,
> all cabs are required to be of the same colors, so they are
> all easy to
> spot.  There are also many, many cabs in Cancun - it appears
> about one in
> six vehicles is a taxi.
>
> On the roads, it appeared to me that frequently cab clusters,
> or several
> cabs near each other, would be driving within two degrees of
> each other,
> often within one degree.  One explanation is that they often
> originate in
> the same location, many waiting at high person-density
> locations like the
> airport, the bus station, etc.  However, I am not sure this
> explains the
> clustering on the roads, as cabs leaving from high density
> locations would
> not leave simultaneously when fares are widely distributed in
> time; they
> also do not have the same destinations.  So, clustering must
> be due to
> something else, I think.
>
> Firstly, cab drivers tend to drive faster than the rest of
> the traffic,
> especially when they have a fare on board.  I am wondering if
> their fast
> driving and deft abilities at weaving in and out of traffic
> allows them to
> agglomerate at stop lights.  As traffic approaches stop
> lights, the slower
> driving traffic still leaves enough space for faster traffic
> further away
> from the light to slip through and make up a few spaces, even
> as traffic
> closest to the stop lights slow down and increase density.  
> After a few such
> lights, faster traffic "sifts" through to the front, and ends
> up at the
> front.  This is just an idea, and no doubt there are a number
> of problems
> with it (for example if cabs also tend to go through yellow
> and red lights,
> reducing agglomeration).  Nonetheless, if the phenomenon is
> real - and I
> observed it to occur more often than just chance would seem
> to explain -
> then there must be a reason for it.
>
> In any event, I would be interested in any input others may
> have about both
> of these subjects.
>
>
>
>
>
>
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