The effect of gull roost deterrence on roost occupancy, daily gull movements and wintering wildfowl

Abstract

Daily gull movements between feeding and roosting sites may present a major hazard to aircraft. One option to avoid this problem is to deter gulls from using certain favoured roosting sites. This may be difficult as the gulls usually roost on water. We assessed whether a large gull roost, at a reservoir near Oxford, UK, could be moved by using taped distress calls and pyrotechnics without causing significant disturbance to wintering wildfowl. Gull movements were monitored during 3 deterrence trials by making weekly counts at several sites. These were compared with seasonal trends in gull numbers at a roost beyond the influence of these operations. Observations and counts were used to investigate the effects on wildfowl. These standard deterrence techniques prevented roost formation so long as an alternative roost site was available; they failed when alternative sites were frozen. Hence the pattern of gull movements in the area was considerably altered by their denial from this important roost. Gull roost deterrence caused no detectable reduction in numbers of any other species, either at the reservoir or in the Oxford area as a whole.