In order to learn more about their reaction to the female sex attractant, 61 male Norway rats were given two-choice preference tests in which they reacted to cues from receptive vs. nonreceptive females. In the first experiment, 16 heterosexually experienced males showed a reliable preference (p< .01) for receptive over nonreceptive anesthetized females, as did 15 naive males (p< .02) which later proved to be copulators. Ten naive males which later proved to be noncopulators showed no reliable preference for either type of female. In the second experiment, 15 naive males which later proved to be copulators showed no reliable preference for the odors from receptive vs. nonreceptive females. From these experiments, we conclude that naive males which later prove to be sexually vigorous are attracted to the composite bodily cues from receptive females, and that this attraction is not mediated by olfactory cues alone.

During a single 1-hr feeding test, adult male Norway rats were offered intact carcasses of adult male rodents, sacrificed by COa asphyxiation. In Experiment 1, 79 Norway rats fed more readily on conspecifics dead 24-120 hr than on conspecifics dead 10 min or 6 hr. In Experiment 2, 22 Norway rats fed readily on roof rats (Rattus rattus) whether they had been dead 10 min or 24 hr. In Experiment 3,15 Norway rats rendered anosmic by zinc sulfate treatment fed more readily on conspecifics dead for 10 min than did 17 controls. In Experiment 4, 34 Norway rats consumed more flesh from house mice coated with roof rat urine than from mice coated with Norway rat urine. It is concluded that Norway rats exhibit a natural aversion to feed on the intact carcasses of freshly sacrificed adult conspecifics in the sense that they are more likely to feed on other species of rodent. The aversion diminishes with the dissipation of the chemoreceptive cue(s) identifying the carcass as a conspecific.Field observations support the view that many animals that rely on scavenging for all or part of their diet exhibit a natural food aversion. That is to say, the scavengers tend to treat the intact carcass of a dead adult conspecific as something less than an attractive food source, sometimes rejecting it entirely, especially if the conspecific has been dead only a short time and if another source of flesh is available. However, in many species, unattended conspecific young are liable to be eaten, dead or alive (