A natural food aversion in Norway rats.

Abstract

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 (

Cadaverine and burying in the laboratory rat

“…As rats tend not' to hoard or eat aversive foods, we were able to demonstrate that the burying of cadaverine -by rats is not a response to an aversive stimulus. In fact, Norway rats prefer to eat 120-h dead conspecifics vs. freshly dead conspecific (Carr, Landauer, Wiese, Marasco, & Thor, 1979). These 120-h carcasses would contain a substantial amount of cadaverine, which forms as a result of the decarboxylation of lysine in the flesh.…”

A natural food aversion in rats rendered hyperphagic by hypothalamic knife cuts

“…The aversion of hungry rats to feed on conspecific flesh is mediated, at least in part, by the same chemical signals by which rats recognize one another as conspecifics (Carr et al, 1982;Carr, Hirsch, et al, 1979;Carr, Landauer, et al, 1979). Moreover, the aversion also depends upon experiential factors (Carr et aI., 1983).…”

“…Hungry Norway rats exhibit an aversion to feed on conspecific flesh in the sense that, during a 1-h test, a large majority remain hungry rather than feed on a dead conspecific, whereas a large majority feed on a dead nonconspecific (e.g., a roof rat, Rattus rattus) rather than remain hungry (Carr, Landauer, Wiese, Marasco, & Thor, 1979). The aversion is mediated, at least in part, by the same chemical signals from the dead rat's furry coat that also mediate species-recognition (Carr, Dissinger, & Scannapieco, 1982;Carr, Hirsch, Campellone, & Marasco, 1979).…”

Growth rate and behavior of Norway rats reared on conspecific flesh

“…Norway rats clearly exhibit an aversion to feed on dead adult conspecifics. For example, a majority (12 of 16) of hungry Norway rats remained hungry rather than feed within 30 min on the intact carcass of a freshly sacrificed adult conspecific, whereas a majority (8 of 11) fed within 30 min on a freshly sacrificed roof rat (Rattus rattus), a congeneric species quite comparable to the Norway rat in size and other external characteristics (Carr, Landauer, Wiese, Marasco, & Thor, 1979). A majority (28 of 32) of Norway rats also fed within 30 min on a dead house mouse (Mus musculus) (Carr, Schwartz, Chism, & Thomas, 1981 .…”