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

[Paul Cherubini]

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.