1976] 
Aspey — Behavioral Ecology in Schizocosa 
45 
tions continued clockwise every minute. This procedure, coupled 
with systematically moving about the field, helped to representa- 
tively sample the spider population. 
Results and Discussion 
In the natural habitat a given male S. crassipes encountered an 
average of four conspeciflcs per minute, which included one fe- 
male and three males (Fig. 1). A Kruskal-Wallis one-way analysis 
of variance (Siegel, 1956) indicated that air temperature fluctuated 
significantly during a given observation session, which lasted 6 
hours (H = 14.07, df = 5, p< .02, two-tailed). Correspondingly, the 
greatest number of individuals were encountered at 1300 hours 
which coincided with the highest mean air temperature (19.4°C). 
Although the mean number of females encountered by a given male 
observation spider did not vary with time, the mean number of 
males encountered varied significantly from 1100 to 1600 hours 
(H = 15.75, df = 5, p < .01, two-tailed). 
This disparity in the sex ratio may be due to: (1) greater numbers 
of males to females; or (2) greater activity on the part of the males. 
Field data from nearly 800 S. crassipes collected in the same area 
during 1970-1973 indicated that the male:female ratio was approx- 
imately 50:50. It appeared, therefore, that the divergent sex ratio 
observed during inter-individual encounters reflected motility 
differences between the sexes. Laboratory analysis of isolated and 
socially grouped males and females supported this hypothesis in 
that males exhibited up to 10 times more locomotory activity than 
females (Aspey, unpublished observations). 
Similar motility differences between male and female Pardosa 
pullata and P. prativaga have been reported by Richter, den Hol- 
lander, and Vlijm (1971), as well as for Lycosa ( Pardosa ) lugubris 
in the field (Dr. S. W. F. van der Ploeg, personal communication). 
In P. amentata, Vlijm, den Hollander, and Wendelaar Bonga (1970) 
considered high levels of male locomotory activity as inherent to 
the male’s age and/or related to the egg sac carrying phase of the 
females. For S. crassipes, the greater activity of the males is par- 
tially attributed to their frequent foreleg Tapping (Aspey, 1974), 
since females do not exhibit such behavior. Whereas most females 
remained motionless throughout the observation period, males 
were rarely stationary. 
