The Effects of Prey Vulnerability, Density, and Patch Replenishment in an Operant Analogue of Foraging

• Main Author: DeWulf, Michael James
• Format: Others
• Published: DigitalCommons@USU 1988
• Subjects: prey vulnerability; density; patch replenishment; foraging; Psychology
• Online Access: https://digitalcommons.usu.edu/etd/5976; https://digitalcommons.usu.edu/cgi/viewcontent.cgi?article=7037&context=etd

Foraging behavior has recently become a popular area of research with which ethologists, behavioral ecologists, and experimental psychologists converge their traditionally separate disciplines into a more multidisciplinary framework. Ethologists and behavioral ecologists usually study foraging as it occurs in the natural environment or the "field," while experimental psychologists contrive laboratory simulations of foraging and make the assumption, sometimes incorrectly, that generalization occurs across settings, situations, and species. Scientific advances are now beginning to occur in the ability of laboratory researchers to better simulate foraging as it occurs in the field. Field researchers are also becoming more willing to accept these findings as important. The purpose of this dissertation was to use a laboratory analogue of foraging behavior to examine the effects of prey vulnerability, density, and prey-patch replenishment on the number of prey rejections and switches between patches. This analogue may have more biological validity than previous simulations in the operant laboratory by simulating conditions of replenishing and depleting patches under adjusting (progressive and regressive) random-ratio schedules of reinforcement. Three experiments were conducted. The first examined the effects of response-cost on acceptability of prey items offered. Results indicated that as the cost of obtaining one prey item increased while the cost of another was held constant, subjects consistently pursued the lower-cost prey and rejected higher-cost prey at increasing probability ratios of 1:3, 1:10, and 1:15. The second experiment covaried response cost (vulnerability) with the probability of encounter (density) for two prey types and evaluated their effects on the acceptability of prey. This experiment showed that when the density of the low-cost prey increased (p = .66), the subjects were more selective. Subjects were less selective when the density of the low-cost prey decreased (p = .33). In the third experiment, prey patches were replenished at reinforcer-determined (regressive random ratio) baseline rates and compared to several fixed-time schedules of patch replenishment. Results of Experiment III indicated no major differences in patch use behaviors (number of switches between patches). The validity and utility of this simulation was discussed as a useful model for the experimental analysis of foraging behavior.