Notes on Two Species of Wood Rats in Captivity

Abstract

A small colony of each of two species of Neotoma was maintained at the Laboratory of Vertebrate Genetics, University of Michigan, Ann Arbor, during 1928, 1929, 1930, 1931, and 1932. One stock was derived from an adult female and two male hoary wood rats, Neotoma micropus canescens, caught three miles north of Carlsbad, New Mexico. The other originated from six female and nine male white-throated wood rats, N. albigula albigula, caught at points near Oracle and Tucson, Arizona. The writer is indebted to Dr. Lee R. Dice and Mr. Philip Blossom for securing and identifying the foundation animals. Grants from the Faculty Research Fund, University of Michigan, supported this work during 1928 and 1929. We maintained these wood rats in the laboratory under the conditions successfully used for members of the Old World genus Rattus. They were confined in wire cages, which had a floor space of 15 x 16 inches and which provided a total space of about 2100 cubic inches. Their diet consisted of one of the uncooked commercial dog foods; a mixture of wheat, corn, and sunflower seeds; rolled oats; and lettuce leaves. In addition, they received cod-liver oil equal in quantity to five-tenths of one per cent by weight of the total food consumed. A small bundle of shredded paper in each cage provided a scanty substitute for their habitually large nests. Each week the sawdust bedding was replaced with clean material. Fresh water was available to the rats at all times. The temperature of the laboratory was maintained within five degrees of 70?F. except on occasional days in July and August. The rats were handled at intervals when weighed or transferred to new cages. There was no indication that they became tame during several years of life in the laboratory. They always struggled violently when handled and sometimes broke their incisor teeth by biting the forceps that held them. In the cages they were timid but not extremely nervous and excitable. When the cage was disturbed they retreated to the rear and thumped the floor with their hind feet in the manner of rabbits. Those individuals born and reared in the cages were not perceptibly tamer than those that were caught in the field.