[Leps-l] monarchs, reversal of orientation and overwintering temperatures

[MexicoDoug]

"modifying cues including some we can only
vaguely imagine like a temperature gradient detecting cue."

  I can see this happening if there is a transition from lake to desert, 
but transition in nature are not always so easily distinguished - would 
you agree?  Though, for the purposes of the experiment the 
Massachusetts group in Chip's links, getting the basic orientation out 
of the flight simulator then might actually be preferred in those 
instances since the obstacles are just going to muck up the results 
unnecessarily in one sense.

It's hard to imagine a too complex sub-gram flying weather station for 
one butterfly to be smarter than NOAA, so it would probably not to be 
that difficult to desigh some experiments maybe best with those flight 
simulators and head source, humidifier/dehumidifier, etc. if what you 
say is true, to observe orientation as a function of gradients in 
controlled conditions.  Also, in the field, I've seen Monarch's 
abruptly change direction when hitting the Sierra Madre Oriental and 
they are good both at climbing as well as paralleling it somehow with a 
tip that a notch or pass is up ahead.  This makes them more complex 
than a simple robot having a switch in each antenna and each time one 
registers to,  e.g., go consistently (counter)clockwise, or not if your 
example is real about the low desert, on one way of the migration 
journey.  But I've always assumed that the first travelers did the hard 
trial and error work and like ants communicated to others since they 
know how to swarm into colonies.  I don't know enough about ants but 
they exhibit similar behaviors in some instances to Monarchs and it is 
possibly done by trial and error (smaller distances but ...) plus 
chemical signaling between or left for others which strangely I've 
never heard mentioned whern Monarchs are discussed.  I don't know how 
effective this would be in the winds but it is also easily testable.

Thanks for your perspectives
Doug
-----Original Message-----
From: Paul Cherubini <monarch at saber.net>
To: Leps List <Leps-l at mailman.yale.edu>
Sent: Fri, Feb 22, 2013 2:40 am
Subject: Re: [Leps-l] monarchs, reversal of orientation and 
overwintering  temperatures

On Feb 21, 2013, at 10:18 PM, MexicoDoug wrote:

> what exactly it is about the flight simulator that
> would cause statistically significant results at all,
> considering it is unlikely the butterfly doesn't have
> a roadmap.

To locate the refrigerator like climate of the Mexican overwintering
highlands or the California coast the monarchs must use multiple
direction finding or modifying cues including some we can only
vaguely imagine like a temperature gradient detecting cue.
Why? Because a southwesterly flight bearing of a fall migrant
monarch in Phoenix, AZ in Sept. would take it into the low deserts
of Baja California which has too warm of a winter
climate to keep it alive all winter.

So the butterflies must be detecting environmental information
in Phoenix area that overides their usual time compensated
Southwesterly sun compass and causes them to fly either
West or Northwest towards the California coast or southeast
towards central Mexico.

The simulator may only allow the butterflies to use their
usual time compensated southwesterly sun compass
and interfere with the other cues that modify or override
the sun compass. So that is why I think the butterflies might
still orient to the Southwest (the wrong way) if tested in
the simulator in Phoenix in September.

> What about the "disappearance bearing"
> method?

That has the same fundamental problem as the simulator; i.e.
the scientists who champion the disappearance
bearing method (e.g. Chip Taylor) have shown no interest in
testing it out in areas like Arizona where the butterflies
don't normally head southwest in September.

Paul Cherubini
El Dorado, Calif.

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