News release/sun compass

John S. Shinal jshinal at
Mon May 5 08:54:32 EDT 1997

On Sun, 4 May 1997 14:18:03 -0500, Monarch Watch
<monarch at FALCON.CC.UKANS.EDU> wrote:
>Monarch Butterflies Use a Sun Compass
>Experimenters have demonstrated sun compass use by controlling
>the timing of lights to shift the internal clocks of subjects. This change
>in internal clocks causes the animals to misinterpret the position of the sun
> and change their direction of movement in a predictable way.
>	Both of the control groups flew in the predicted SSW direction.
>However, the clock-shifted butterflies flew toward the WNW.  Even though it
>was 3:00pm, the clock-shifted butterflies "thought" it was 9:00am, and flew
>in a direction to the west of the sun's position.

	An interesting side thought :

	Natural variation in Local Mean Solar Time as a function of
longitude should thus "spread" the navigational directional error of
insects in different longitudes.

	How large might this error be in square kilometers at the end
of the migration ? The "pilgrims" might simply get fairly close to the
destination and then use pheromones or similar chemical cues as a
"terminal guidance" method.

	Of course, I am an amateur, and that is just fun speculation.

	John S. Shinal
	jshinal at

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