Excretory deposits surrounding food sites facilitate social learning of food preferences in Norway rats

Experiments were conducted to investigate the communication and social learning of food preferences via excretory marking amoungst adult male Norway rats, Rattus norvegicus. In experiment 1 animals were placed in a large enclosure with a choice of two food sites each containing a different novel food. For rats in the experimental conditions the enclosure had previosly house four "demonstrator" conspecifics that had eaten one of the foods at one of the sites, whilst controls were placed in a clean enclosure. Experimental animals consistently ate more of the diet eaten by their demonstrators than controls, and consumed more food in total. The experiment also investigated whether this marking of food sites could result in social learning. Animals were replaced in a clean enclosure with a choice between the two foods at unmarked sites, 24 h after their first experience in the soiled enclosure, and again exhibited a preference for the demonstrators' diet. The remaining experiments investigated the communication process underlying these results. From these it is concluded that what renders food sites attractive to ras is a stimulus complex that includes local urine marking of the sites and peripheral urinal and faecal deposits, neither of which on their own is sufficient to mediate the transmission of information about food preference, but which together is an effective means of transmitting information between rats.