1977] 
Kanz — Monarch Butterfly Orientation 
137 
periphery cages) was not as conclusive, statistically, as the sun ori- 
entation of summer non-migrants in opaque periphery cages. Fur- 
thermore, a stronger escape response could be expected to be posi- 
tively correlated with a greater overall level of activity within a 
cage. It Was found, however, that cage activity during fall tests was 
less than cage activity during summer tests. 
The tendency of fall migrants to orient more closely to the sun’s 
azimuth during the observed fall migratory period (1000-1400 hrs, 
EST) was another feature distinguishing fall migrant sun orienta- 
tion from escape response sun orientation. A sun orientation re- 
stricted to the period 1000-1400 hrs would offer several advantages 
to Monarchs migrating south: (1) A restricted sun orientation en- 
compasses an arc of 60° to 70° compared with an arc of 160° to 
180° resulting from all-day sun orientation and the 60°-70° arc 
rarely deviates from the desired south to southwest migratory di- 
rection. (2) Consequently, the distance traveled, and time and 
energy expended, would be less. Tunmore (1960) has suggested a 
similar scheme for bird navigation. (3) A restricted sun orientation 
also obviates the necessity of sun-compass orientation to explain 
the precision of the Monarch’s long-distance fall migration. The 
data suggest that the restricted sun orientation was independent of 
temperature (for ambient temperatures greater than 1 3° C). (4) Since 
the highest autumn temperatures generally occur between 1000 hrs 
and 1400 hrs (EST), fall migrants would be migrating during the 
warmest part of the day. 
If fall migrants use sun orientation, then spring migrants return- 
ing north might use a negative sun orientation. Reversed orienta- 
tion by insects between leaving and returning to a site is well known 
(Geir, 1960; Johnson, 1969; Kennedy and Booth, 1963; Pickens, 
1934; and Shephard, 1966). 
Monarch migrations are undoubtedly affected by winds. How- 
ever, while Monarch migrations appear to be aided by prevailing 
winds, they are not as dependent on them as locusts (Waloff, 1946, 
1958) and aphids (Johnson, 1954, 1969). Figure 7 showed that the 
distributions of release azimuths were tighter when migratory and 
down-wind directions coincided than when the two directions dif- 
fered. Furthermore, several instances were recorded (Kanz, 1973) 
where fall and spring migrants were engaged in directed migratory 
flights with little or no wind. The prevailing surface wind patterns 
for up to 500 m altitude (Prevailing Direction, Mean Speed and 
