During 1 April - 24 June 1983, daily bird-scaring operations were undertaken by a private contractor at Quinted Sanitary Landfill Site SLS to help reduce hull numbers at nearby CFB Trenton. We made independent bird observations each week during that same period both at Quinte SLS and at two control SLSs where no bird-scaring operations took place. The effectiveness of individual visits to Quinte SLS by the bird-scaring personnel was usually of short duration about 30 minutes after departure of the bird-scaring personnel gull numbers increased to those prior to the scaring operations. Prior to bird-scaring operations, gull numbers at Quinte SLS were most likely similar to those at the control SLSs. The frequent 2 or more a day bird-scaring visits to Quinte SLS resulted in a large reduction in gull numbers, as compared to gull nunbers at the control SLSs and to the number of gulls that was most likely present before the scraing program. The long-term, cumulative effect of the persistend harassment of the gulls was a large drop in gull numbers, despite the fact that individual bird-scaring visits had only limited success.