An evaluation of winter roost harassment for dispersing double-crested cormorants away from catfish production areas in Mississippi

We evaluated the effectiveness of harassing wintering double-crested cormor ants (Phalacrocorax auritus) at their night roost sites over a 3-winter per iod as a means of reducing their impact on the catfish industry in the Delt a region of Mississippi. Cormorants were dispersed from night roost sites b y persons firing pyrotechnics at the birds in the roost and at those flying towards the roost for a 2-hour period before sunset. Numbers of cormorants at intensely harassed roost sites were greatly reduced in comparison with numbers at roosts that were not harassed or less intensely harassed. Number s of cormorants surveyed on or near catfish ponds in March also were reduce d by greater than or equal to 70% during years of extensive harassment comp ared with numbers surveyed the year before harassment. Catfish producers wi thin an area of intensive roost harassment perceived a reduction in problem s with cormorant predation during the years of harassment as compared to pr evious years. Producers within this roost harassment area also reported spe nding less money on cormorant control on their farms. Those outside the roo st-harassment area reported spending more.