Sand digging contingent upon bar pressing in deermice ( Peromyscus)

Abstract

1. 1. Five stocks of Peromyscus were tested for the quantity of sand they could remove from a tunnel in 24 hours. The stocks were P. maniculatus bairdii (domesticated and first laboratory generation of wild caught), P. maniculatus gracilis, P. leucopus, P. floridanus. 2. 2. P. m. gracilis dug significantly less sand than the other species, which did not differ, except for the first laboratory generation of wild caught P. m. bairdii, which failed to dig. 3. 3. A second experiment testing the reinforcing value of sand digging was performed with P. leucopus. The opportunity to dig sand was contingent upon pressing one of two bars, which provided sand over a period of 24 days. 4. 4. Acquisition of the position discrimination occurred during the first 12 days, but reversal learning did not take place during the second 12 day period. Controls receiving no sand had a significantly lower bar pressing rate than those making the discrimination. 5. 5. The results suggest that phenotypic expression of the genotype in terms of habitat selection and habitat utilization depends to a certain extent upon the reinforcing properties of the environment,