Starling control in livestock feeding areas

Research efforts to combat the problem of European starling damage in livestock feeding areas (feedlots) by developing appropriate toxicants and stupefacients are described. Of about 500 chemicals screened for possible utility, 4 compounds showed promise at potential toxicants for further development and testing: TEPP (tetraethyl pyrophosphate), DRC-632 (0-[4-(methylthio-m-tolyl] phosphorothioate)), DRC-1327 (4-aminopyridine), and DRC-1339 (3-chloro-p-toluidine hydrochloride). TEPP was found to be too toxic to mammals to further develop its potential use against starlings. However, because it causes rapid death, it was useful in subsequent tests of bait acceptance by various avian species. DRC-632 was the first material noted to be far more toxic to birds than to mammals. Dermal toxicity proved more important than oral toxicity, but its extreme secondary hazard, especially to avian predators and scavengers, made it generally unsuitable for use. DRC-1327 was found to cause birds to emit distress cries and violent reactions in birds ingesting the materials, which often died, but also causing flocks to abandon the treated area. Field trials showed promise, and when bait acceptance by starlings is poor or fair, it is more effective than other known toxicants in reducing damage. DRCC-1339 (Starlicide) is the most selective bird toxicant presently known, providing starling control that is virtually nonhazardous to other animals. Discussions of bait materials and formulation, active ingredient dilutions, and baiting methods are provided