Laboratory study of wild rats *

Boice (1971) has recently described procedures for trapping, maintaining, and studying wild Norway rats (Rattus norwegicus) in the laboratory. He suggests that a major reason for studying wild Norway rats is to determine how the process of domestication has influenced the behavior of this species. There are other reasons for the laboratory study of wild animals, one of the most important being the establishment of behavioral principles and laws which extend over many species. In his recent provocative article, Lockard (1968) cast doubt upon the validity of results obtained from domesticated rats in relation to species which are products of a natural environment. This criticism can be met by the study of nondomesticated species, particularly those which are closely related to domesticated rats, for greater generality should be observed the closer the relationship between species. The procedures described by Boice (1971) for trapping, maintaining, and handling wild Norway rats are quite elaborate, and could discourage some researchers. This paper is intended to provide information on three wild rat species studied in my laboratory which do not require handling and maintenance procedures different from those employed with domesticated rats. Black rats (Rattus rattus) , cotton rats (Sigmodon hispidus) , and wood rats (Neotoma j7oridana) (powell & Morris, 1968; Powell & Mantor, 1970 ; Powell, 1971) have been studied in this laboratory. The first two species appear quite suitable for conditioning experiments, but wood rats have adapted poorly to captivity. Some members of this species appear to go into a state of shock when trapped; some do not eat in captivity, and , consequently, I have experienced a mortality rate of 70% to 80% within 10 days following capture. For black rats and cotton rats, mortality rates over the same period have been practically zero. This difference in adaptability between species is, of course, an interesting topic in itself for research.