Date of this Version
A review of the literature on this subject reveals there is considerable confusion regarding the meaning of the word "repellent" as it relates to animal control. Some people make a liberal interpretation and include any material or device that will alter the pattern of activity of an animal through response to sight, sound, taste, odor, or touch. Although such an interpretation may be valid, for this paper I would like to confine my discussion to "chemical repellents" -- materials that, when applied to seeds, plants, or other materials being damaged by animals, will reduce depredation through taste, odor, or possibly irritation. The idea of using distasteful or foul-smelling materials to prevent losses from animals is not new and probably goes back to antiquity. Since World War II, however, increased importance has been placed on this method of "control", and research has been stepped up in recent years in an effort to develop more effective and useful materials to reduce losses by rodents, deer, rabbits, birds, and other animals that damage orchards, agricultural crops, and forest seeds and seedlings, and by commensal rats and mice that damage food packages, textiles, and other materials of economic importance. As many of you know, the Denver Center has played an important part in this work. Much of this research has been made possible through continuing grants from the U. S. Army. The Army's Electronics Command recently increased its support to speed up research on protecting cable from rodents because of damage being experienced in Vietnam. The search for chemical repellents also gained ground as a result of the recommendations of the Leopold Report, which stated, "We further recommend that the [Bureau's] research program shift some of its attention from methods of killing animals to ways of preventing depredations by repelling, excluding, or frightening animals." To accomplish this, major changes have been made in our chemical screening and development program, and the outlook for improved contact repellents looks promising (Kverno et al., 1965).