1977] 
Kanz — Monarch Butterfly Orientation 
129 
The orientation of summer laboratory-reared, non-migrant Mon- 
archs in transparent periphery cages was random with or without 
the sun visible (Table II), and was comparable to the random 
orientation shown by opaque periphery cage non-migrants and 
migrants in the absence of sun cues. Therefore, the presence of 
terrestrial cues over-rides the sun-orienting escape response of 
non-migrant Monarchs. It is possible that using terrestrial instead 
of sun cues each non-migrant butterfly persisted in its orientation 
cue for escape. These experiments demonstrate that the majority 
of non-migrant Monarchs chose terrestrial rather than sun cues for 
orientation when both were available. 
Fall migrants, exposed to both terrestrial and sun cues, continued 
to orient to the sun’s azimuth (Fig. 4, Table II) with an orientation 
closer to the sun’s azimuth from 1000-1400 hrs, EST, than either 
before or after this period (| 0-sun azimuth | value being 35°, 52° 
and 77°, respectively). An exception was seen in one sun-visible 
test, in which 0’s from most significantly grouped animals main- 
tained an approximately 240° heading (southwest). However, this 
occurred only once and one cannot determine whether terrestrial 
or celestial cues were used. Random orientation resulted with 
terrestrial cues present but sun clues absent (Table II). The per- 
sistent sun orientation of fall migrants, when the sun and terrestrial 
cues were visible, is additional support for the hypothesis that the 
sun orientation of fall migrants is a migratory response and not 
merely an escape response. 
Flight Directions Following Release 
Monarchs were released after each experiment and an azimuth 
reading taken on the vanishing direction of each butterfly using a 
Silva compass compensated for declination angle. Only those but- 
terflies that flew to the horizon were used in the analysis of Monarch 
vanishing directions. All Monarchs exhibited speed flight (Urqu- 
hart, 1960) immediately upon release. Occasionally Monarchs 
showed a feeding flight pattern with short randomly directional 
flights between flowers. When feeding flight took a butterfly to 
the horizon of the test field within 2 minutes, its azimuth at the 
periphery was included in the analysis; if feeding flight persisted, 
the vanishing azimuths of such animals were excluded from com- 
putations. Flight altitudes of released Monarchs were evenly di- 
vided between those above and below approximately 8 meters. 
