Attempted Relocation of a Ring-Billed Gull Roost at Washington National Report

Gulls, particularly ring-billed gulls [Larus delawarensis ], have been identified as a threat to aircraft operations at Washington National Airport (now Ronald Reagan National Airport) in northern Virginia. Through bird surveys conducted in 1992, 1993, and 1997, an estimated 7,000 gulls were observed roosting during winter on the Potomac River near the airport. A harassment program was run on 5 consecutive evenings, 24-28 February 1997, to relocate the roosting gulls. Six to 8 people shot pyrotechnics from shore and 2 boats for 2 hours prior to dusk each evening. Each evening the gulls arrived consistently later than the prior evening and formed the roost in different locations on the Potomac and Anacostia Rivers. No difference in gull numbers was seen within critical airspace or on the airport through bird surveys conducted before, during, and after the harassment program. Although the harassment program seemed to change the gulls’ behavior, no significant difference was observed in the threat presented by gulls to aircraft. Potential alternatives to increase the effectiveness of future harassment programs include harassing the gull roost earlier in the winter season and reinforcing harassment with lethal shooting