Aerial treatments against starling roosts in France with chloro-para-toluidin (CPT): Results of eight years of experiments

The starling is one of the major pest birds in France. During the winter, starlings coming from other parts of Europe gather in the Northwest of France and cause extensive damage in the corn silage distributed to the cattle, by eating and spoiling the grains. As it is impossible to protect the cattle food by physical means in most of the situations, the persons in charge of resolving the problem have chosen to turn towards chemical roost treatments. Between 1980 and 1988, nearly 40 treatments have been carried out on 25 different roosts. The chemical used is CPT (chloro-para-toluidin) applied at the rate of 100 kg per hectare. Water is added to the formulated product and a volume of 1000 liters per hectare of the treatment mixture is applied with a fixed-wing aircraft. Results usually ranged from 30% to 80% of the birds killed. No phytotoxic problems have been reported on the roost sites, and only light wildlife adverse effects arc mentioned. Studies are going on with the following points: degradation of CPT in the soil, and reduction of the amount of CPT and/or water without drop of effectiveness