Pestic. Sci. zyxwvutsrqpo 1993, zyxwvutsrqp 39, 299-304 Evaluation of a Pelleted Bait Containing Methyl Anthranilate as a Bird Repellent J. Russell Mason," Larry Clark US Department of Agriculture, Animal and Plant Health Inspection Service, Denver Wildlife Research Center, zyxwvutsrq c/o Monell Chemical Senses Center, 3500 Market Street, Philadelphia, Pennsylvania 19 104-3308, USA zyxwvutsrq & Timothy P. Miller Agricultural Research Division, American Cyanamid Company, PO Box 400, Princeton, New Jersey 08540, USA (Revised manuscript received 14 May 1993; accepted 25 July 1993) Abstract: No-till agriculture involves the use of granular pesticide formulations, chemically treated seeds, and pelleted baits. Some of these may accidentally kill birds. We have tested whether methyl anthranilate (MA), a known bird repellent, would eliminate consumption of a pelleted bait. In two laboratory experiments and an outdoor aviary trial, cowbirds zyxwvut (Molothrus ater Bodd.) were presented with pellets containing pesticide and MA, pellets containing pesticide but no MA, and carrier pellets without pesticide or MA. Consumption of any formulation was low, but the addition of MA significantly decreased bait loss in the laboratory, and prevented the disappearance of bait in the outdoor trial. 1 INTRODUCTION No-tillage conservation farming is becoming common for both environmental and economic reasons.' Overall, these farming practices benefit wildlife because they preserve food and cover, and because they often do not involve broadcast spray applications of pesticide.2How- ever, granular pesticides, pelleted baits, and chemically treated seeds (hereafter referred to collectively as PF) are essential components of no-tillage farming; some of these products are toxic to birds3-, and may easily be mistaken for food or grk6 Because of the dangers to wildlife, the Environmental Protection Agency restricts and occasionally bans the use of various PF. There is ample statutory justification for this position. The Migratory Bird Treaty Act sets zero tolerance for bird mortality from human a~tivities.~ One solution to the problem of accidental poisoning * To whom correspondence should be addressed. by PF may be the use of bird-repellent additives in these products. Methyl anthranilate (MA) could be one such additive. This human food flavoring is offensive to many bird species at concentrations between 5 and 10 g kg-1,8,9 and the available data suggest that it is as effective in the field as it is in the laboratory.'O~'lIt is not considered toxic to mammals or birds, available toxicity values by dietary and acute oral exposure being: mouse LC,, = 3900 mg kg-l; rat LD,, = 3288 mg kg-'; quail LC,, > 5600 mg kg-'; quail LD,, > 290 mg kg-' (precise avian LD,, values have not been determined-birds regurgitate higher dosages) (P. Vogt, pers. comm.). In the present assessment, MA was incorporated into PF pellets and the pellets were presented to cowbirds in two laboratory experiments and an outdoor aviary evaluation. Our primary objective was to determine whether MA would decrease PF ingestion. In addition, because pellets containing pesticide but no MA, and pellets without pesticide or MA also were presented, we were able to examine whether the pelleted baits, per zy se, would be ingested by cowbirds. 299 Pestic. Sci. 0031-613X/93/$06.00 0 1993 SCI. Printed in Great Britain