Does shooting disturbance affect diving ducks wintering on large shallow lakes? A case study on Lough Neagh, Northern Ireland

Waterfowl hunting is widespread and common throughout Europe, affecting waterfowl populations directly through the kill and indirectly through disturbance. Freedom from such disturbance is an important part of waterfowl management. However, most studies of the effects of disturbance on duck populations have been site specific with few attempts to synthesis the results of these local studies and use them in management strategies. Lough Neagh has the largest surface area,of any freshwater lake in the British Isles. It is also relatively shallow with a mean depth of ca. 9 m. The seasonal effects of shooting disturbance on the daytime distributions and behaviour of wintering Pochard Aythya ferina, Tufted Duck A. fuligula, Scaup A. marila and Goldeneye Bucephala clangula was studied during the winter of 1998/1999. The nocturnal use of shoreline areas was also studied using an image-intensifing telescope. The distributions of wintering Pochard, Tufted duck and Scaup were shown to be affected by shooting disturbance on Lough Neagh. But because they were also shown to predominantly roost during the day, and were not observed to forage in the marginal areas of the Lough throughout the winter period at night, any energetic consequence of shoreline based shooting disturbance is likely to be small. Goldeneye predominantly fed during the day. It would be expected that diurnal feeding Goldeneye would show the biggest response to shooting disturbance during the day, but proportions observed in designated zones during and after the shooting season did not change significantly, confirming the lack of effect. Observation of Pochard and Tufted Duck engaged in various behaviours did show an increase in the proportion of ducks feeding, after the shooting season had closed. The increase was attributed to increased feeding prior to migration as opposed to being the result of the cessation of shooting disturbance. The most important factors to consider when applying conservation measures to diving duck populations wintering on lakes with similar attributes are identified and discussed. (C) 2001 Elsevier Science Ltd. All rights reserved.