1977] 
Kanz — Monarch Butterfly Orientation 
127 
TIME OF DAY IN HOURS C E ST) 
Fig. 3. Orientation of fall migrants captured in the field and tested in opaque 
periphery orientation cages on a clear day. The orientation displayed by these 
migrants was a sun orientation. 
The consistently random orientation of all Monarchs in no-sun 
tests, and the random orientation of summer non-migrants reared 
under a photoperiod advanced 6 hours and tested on no-sun days 
(Table I), argue against a time-compensating, sun-compass orienta- 
tion in experiments with opaque periphery cages, von Frisch (1967) 
showed that a patch of blue sky subtending an angle of only 10° to 
15° was not only sufficient for the honeybee to localize the sun’s 
position, but also that the honeybee was capable of a sun-compass 
orientation using polarized light. The sun’s position can be uniquely 
described for most times of the day by the pattern of polarized light 
(Stockhammer, 1959; von Frisch, 1967). Experiments with summer 
laboratory-reared non-migrants and fall Monarchs suggested that 
the sun orientation of these animals was dependent on the sun 
being directly visible. On partly cloudy days, opaque periphery 
cage non-migrants and fall migrants oriented randomly when the 
sun was obscured by clouds but sun-oriented when the sun was not 
obscured by clouds. Summer non-migrants (laboratory-reared) and 
fall migrants, in opaque cages with a sun-shade blocking the sun 
but the remainder of the sky visible, showed a random orientation 
with the shade in place and a sun orientation when it was removed 
(Table I). 
Orientation in Transparent Periphery Cages 
Tests performed with transparent periphery orientation cages 
exposed Monarchs to terrestrial as well as celestial orientation cues. 
