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Psyche 
[March 
quadrat sampling techniques are influenced by the size of the 
quadrat (Pielou, 1969). It would have been desirable in this study 
to use larger sample quadrats in addition to those employed. This 
was not done because pilot studies indicated that as quadrat size 
increased, it became increasingly difficult to accurately count the 
bees in a very short period of time. 
Other studies suggest that animal foraging patterns vary accord- 
ing to resource distribution and abundance. Michener’s observa- 
tions (pers. comm.) of seemingly clumped bee patterns, were 
made in a semi-desert area of southern California at a very sparse 
resource, Chrysothamnus bushes. Two strategies are exhibited 
by the ant, Veromessor pergandei, depending on food abundance 
(Bernstein, 1975). When food is abundant the ants forage inde- 
pendently, but when food is scarce they forage in groups. Some 
birds forage in flocks when food is uniformly distributed and scarce 
(Cody, 1971). Heithaus et al. (1974) found that some bats lap only 
a small portion of the nectar during a flower visit, thereby main- 
taining an abundant resource. These bats forage independently. 
In the present study, bees were observed foraging at very dense 
arrays of C. arvensis flowers. The abundance and uniformity of 
the resource were maintained by the continuous replenishment 
of pollen and nectar. Pollen was dehisced during much of the bees’ 
foraging period (personal observation), and unpublished data 
provided by R. W. Thorpe suggest that nectar may be continuously 
secreted from time of anthesis until late morning. As suggested 
by Cody (1971) for birds, independent bee foraging may be favored 
at an abundant resource, such as the C. arvensis patch. However, 
the bees’ foraging patterns may vary in response to different re- 
source patterns or different bee densities. 
Further investigations, using similar and different censusing 
techniques, are needed to elucidate bee foraging patterns in relation 
to resource patterns. Studies of several bee species may suggest 
some general patterns. 
Acknowledgments 
I thank M. D. Breed, C. D. Michener, T. P. Snyder, and B. L. 
Waddington for helpful suggestions on the manuscript. Thanks 
also to R. W. Thorpe, University of California, Davis, for permit- 
ting me to see unpublished data. 
