A new approach for the control of nuisance and depredatory birds is offered by the use of chemically treated baits which produce flock-disturbing reactions. Physiological effects involving unusual actions and calls disturb and warn unaffected birds of impending danger, thus inducing them to abandon the area. The two most effective chemicals found so far are 4-nitropyridine-N-oxide (Avitrol2 100) and 4-aminopyridine (Avitrol 200). These chemicals are toxic when ingested in sufficient amounts, but the mortality can be controlled by adjusting the concentration in the bait. One highly desirable feature is the lack of secondary poisoning by these chemicals. Excellent results have been obtained on sparrows (Passer domesticus), pigeons around buildings, and starlings (Sturnus vulgaris) in feedlots. Good preliminary results have been obtained in tests against birds in standing grain but research is continuing in this area. Gulls on airports have responded to this method, and crows (Corvus brachyrhynchos) have been driven from the environs of an airport in a single test. Where treated baits can be left in suitable feeders, control of pigeons and sparrows has been effective for more than a year. The control of damage by birds has involved many approaches which have been thoroughly reviewed (de Vos 1963). Many wildlife experts agree that, in the control of depredating or nuisance populations, a mass killing or other removal is generally unsatisfactory. A local situation may be improved for a time but rapid population replacement often occurs. A better method is to induce the population to abandon the area where they are creating a problem. A method for bird control employing this principle has been developed which is based on the creation of an avoidance reaction by feeding chemicals that produce physiological responses in the affected birds (Goodhue and Cantrel 1962, Goodhue et al. 1963, Goodhue et al. 1964). The actions and calls of these affected birds are sufficiently disturbing to other members of the species in the vicinity that they abandon the area. This method works best on the more social species where communication appears to be well developed. With species less sensitive to the reactions of other birds a much larger segment of the population must be affected. Conditions in each situation will dictate the quantity of chemical to be used, but in each instance it is desirable to leave a large segment of the population with a communicable knowledge of danger. This new principle of bird control was discovered during a search for true bird r pellents, when grain bait coated with various chemicals was offered to natural populations of pigeons and sparrows. During a test on 4-nitropyridine-N-oxide, pigeons were found walking on the ground nable to fly. Most of those that did not become victims of predators recovered, but avoided the house where they had received this chemical until it was torn down 3 months later. The full potential of this discovery was not realized until similar results were obtained on birds in a field of standing grain. Impetus was added to the investigation by the fatal bird-induced disaster at Logan Airport, Boston, Massachusetts, in October, 1960 (Boyd et al. 1962), and the subsequent finding that gulls could be dispersed from airfields by the application of treated bread. The contributions of A. J. Reinert, R. E. Marquardt, R. E. Stansbury, and Stephen 1A joint contribution from the laboratories of Phillips Petroleum Company, the Research Foundation and the Zoology Department (No. 400), Oklahoma State University. 2 A Phillips Petroleum Company Trademark.