lizard | .20 | .09 | .18 | .09 | .07 | .11 | .01 | .01 | | | | | | | | | | snake | .20 | | .07 | .06 | .05 | .04 | .05 | .08 | .12 | | | | | | | | | _Microtus_ | | | .04 | .02 | .08 | .13 | .09 | .12 | .25 | | | | | | | | | _Peromyscus_ | | .09 | | .02 | .05 | .06 | .03 | .05 | .04 | | | | | | | | | "other mammal" | | | | .01 | .04 | .10 | .03 | .03 | | | | | | | | | | bird | | | | | | | .01 | .01 | +-----+-----+-----+-----+-----+-----+-----+-----+---- Total prey items| | | | | | | | | for size group| 5 | 23 | 28 | 101 | 120 | 121 | 127 | 76 | 24 --------------------+-----+-----+-----+-----+-----+-----+-----+-----+---- The wide disparity in size between young and adult racers also results in utilization of different food sources to some extent. In some kinds of snakes adults and young draw their food from entirely different sources, but in the racer there is broad overlap, as shown in Table 6. The samples from the largest and smallest size groups of racers are relatively small. Two important kinds of prey--voles and grasshoppers of the genus _Melanoplus_--were not found at all in the smallest size groups of snakes and comprised increasing percentages in the food of the larger size groups. A large adult vole is too large to be swallowed except by an unusually large racer, and a young vole old enough to leave its nest is far too large for a hatchling racer. Grasshoppers of the genus _Melanoplus_ are relatively large and heavily armored, and so are relatively immune to attacks from the smaller snakes. Small soft-bodied orthopterans including _Gryllus_, _Ceuthophilus_ and _Orchelimum_, and also lizards and snakes, are best represented in the food of the smaller racers. Other types of prey showed no definite correlation with size of the racer taking them. Reproduction _Sexual Behavior_ Many observers have published accounts of the courtship and/or mating of the racer, but all of these are, to some degree, incomplete. Because of the widely different circumstances, and the different viewpoints of the observers involved, the several accounts give much different impressions of sexual behavior in this species. Either singly or combined, the published accounts do not provide an adequate description of the process.