350 
Psyche 
[Vol. 94 
Environmental measurements 
Over a five-day-period during the final release experiments, some 
of the environmental factors which may have caused spiders to 
relocate were monitored in the two habitats. In both the deciduous 
forest area and the pine stand, temperature and humidity were 
recorded every three hours from 0900 through 1800 hours, at two 
randomly chosen quadrats. Humidity was measured using a 
Mason’s hygrometer (Taylor Instruments, Arden, N.C.) and tem- 
perature readings were obtained from the dry bulb of this instrument. 
Sticky traps were set out at these same sites to estimate prey availa- 
bility in the two habitats. These traps consisted of a 20 cm diameter 
embroidery hoop covered with a double layer of cheese cloth. The 
cheese cloth was coated with Stickem Special (Seabright Enter- 
prises, Emeryville, Calif.), an insect trapping compound. The traps 
were suspended one meter above the ground (which approximates 
the average height of a M. gracilis web; (Hodge 1985)). I set these 
out at 0700 and retrieved them at 1800 hours. Trapped insects were 
removed and identified to order and their body lengths were meas- 
ured to the nearest mm. During this five-day-period, all webs in the 
study area were visited every three hours and thermoregulatory 
positioning by the spider and web condition (damaged or undam- 
aged) were recorded. 
Results 
I was able to follow 19 of the 23 spiders released into the pine 
stand, and 19 of the 32 released into the deciduous forest. Residence 
times at web sites for spiders released into each habitat were signifi- 
cantly different (t-test, p < 0.01; Fig. 1). The mean residence time at 
a given site by spiders in the deciduous forest was 8 days (S.D. = 4), 
whereas spiders in the pine stand only stayed an average of 1 day 
(S.D. = 2) at a web site. By September 9, the last census day, almost 
all spiders released into the pine stand had, through successive web 
relocations, moved into the deciduous forest or had disappeared 
from the area (Fig. 2). Exceptions included three spiders that did 
not build webs over the six days that they were observed before they 
disappeared. Three other spiders successfully maintained webs in 
the pine stand, but all were near the transition zone to the deciduous 
section (Fig. 2). None of the spiders released into the deciduous 
fores* was ever observed to have moved into the pine stand (Fig. 3). 
Spiders released within the deciduous woods usually moved from a 
site of deciduous canopy to similar sites, but sometimes moved to 
quadrats with no canopy (Table 1). 
