Effects of poisoning on predatory and ingestive behavior toward artificial prey in rats (Rattus norvegicus)

Ingestion of novel prey by vertebrate predators that is followed by illness typically decreases the predators' eating the prey more readily than their pursuing or killing it. We used artificial prey-food items (rolling ball bearings that predicted food pellets) to model and extend this finding in laboratory rats. During daily experimental sessions presentations of a novel bearing-food combination were intermixed with presentations of a familiar bearing-food combination. The poisoned animals received lithium chloride injections after each session. Experiment 1a showed that: (a) Poisoning markedly decreased ingestion of the novel food without decreasing the frequency of contact (nose, seize, carry, or chew) with the novel bearing predicting that food. (b) However, poisoning did significantly decrease the average duration of contact with the novel bearing. (c) Poisoning did not decrease behavior toward the familiar food and bearing. Experiment 1b showed that after moderate exposure to pairings of the novel food and bearing, poisoning decreased behavior toward both novel and familiar food and bearings. The results indicate that important aspects of predation can be simulated and examined in the laboratory by using artificial prey-food items. These results also support the conclusions that predatory behavior and ingestion reflect separable modes of behavior and that the presence of novel prey interferes with the generalization of poisoning effects to familiar prey.