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This study reports on field tests of the Schoener (1979) and Orians-Pearson (1979) models of central-place foraging for single-prey loaders. Solitary pine squirrels defend territories and harvest the cones of lodgepole pine for storage at a central midden site. Squirrels forage differentially among the trees in their respective territories because the cones of different trees differ significantly in size, shape, and number of seeds per cone. Cone choice was investigated as a function of distance from the central cache and as a function of whether cones were harvested for immediate or later use. The results are as follows. 1. The positive relationship between prey size (i.e., prey quality) and distance predicted by both the Schoener and Orians-Pearson models is strongly supported. Two measures of prey quality (the percentage of total cone weight attributable to seeds and the number of seeds per cone) correlate positively with …