The movements of wild rats are largely the result of the two inherent (but
opposing) tendencies to explore and to avoid (Barnett 1956). The complex
interaction between different behavioural responses to food and bait stations by
various rats was well summed up by Shepherd & Inglis (1987), discussing
commensal Norway rats: ‘We have two possible answers to the question of
“Which rats do not eat the poison when a treatment fails?” The first is that it is