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Colony roosting species of blackbirds (Icterinae), including European starlings (Sturnus vulgaris), can be significant pests. The chemical avicide CPT has been applied experimentally in the U.S. and France to roosting blackbirds. However, apparent effective aerial application rates are high, 44-101 kg/ha (40-90 lbs/a), and the actual efficacy, expressed as percent mortality, is difficult to determine. We assessed CPT as a respirable aerosol for potential use as a roost avicide. Starlings exposed to 17 ppm CPT for 5.5 min received lethal doses. The birds appear very sensitive to CPT administered in this manner. The methods of CPT entry into the birds include respiratory, ocular and dermal. It is proposed that a field application rate of 3.4-5.6 kg of CPT per hectare (3-5 lbs/a) would be effective.