Fig. 6. Release orientation for summer monarchs on overcast days. Symbols 
are as in Fig. 5. Most vanishing directions were down-wind. 
(1960) has observed that Monarchs tend to avoid flying over water 
when possible. Most flights in (m) were low to the ground, as was 
true for the majority of flights showing vanishing azimuth into the 
wind. The releases of (t) occurred at 1600 hrs (EST) when migrants 
return to roosting trees for the night. The roosting trees for mi- 
grants at Gloucester were west and northwest of the release and 
feeding sites. Thus, the migrants of (t) were possibly returning to 
their roosting trees; however, it is unclear why the butterflies in 
(c) chose a similar direction at 1300 hrs (EST) with the same wind 
velocity as in (t). 
Vanishing directions appeared to be down-wind, particularly 
when winds exceeded 10 mph (16 km/ hr) unless the butterfly flew 
low to the ground. Two-way analysis of variance between the mean 
angular deviation of 22° for (h), (i), (k), (1), (n) and (o) and the 
mean angular deviation of 42° for the remaining fourteen release 
distributions indicate significant differences (F = 9.5, df = 16, P< 
.01). In the former case, the wind was blowing in the same direction 
(southwest) as the sun’s azimuth. In the latter case, the wind and 
sun azimuth directions did not coincide. Analysis of variance of 
