Experimental refuges for migratory waterfowl in Danish wetlands. I. Baseline assessment of the disturbance effects of recreational activities

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Abstract
1. Potential human sources of disturbance, including fishing, sailing, windsurfing and different types of waterfowl hunting, are described and their effects on autumn‐staging waterbirds, including mute swan, wigeon and coot, were examined at a coastal wetland in Denmark from 1985 to 1988. 2. Bird and human distributions were superimposed on the distribution of submerged vegetation and water depths to identify the extent of spatial overlap; likewise, seasonal and diurnal temporal overlap in bird abundance, and human activities were defined. Behavioural and distributional reactions of waterbirds to different human activities, in terms of escape distances, disruption of activity patterns and redistribution, were assessed to establish their relative effects. 3. Sailing and windsurfing showed little spatial overlap, and fishing partial spatial overlap with bird distributions; these activities almost ceased before the peak in autumn bird numbers. Hunting showed a high degree of spatial and temporal overlap with bird presence. 4. Birds responded to windsurfing at greatest distances, whereas hunting (especially from mobile punts) caused the longest disruptions to activities of waterfowl. In terms of behaviour and redistribution, wigeon was more affected by shooting than was mute swan or coot. One or two mobile shooting punts reduced wigeon numbers, whereas numbers were unaffected by the presence of up to 4–6 stationary punts; fishing boats had no effect on wigeon abundance. 5. Hunting, especially shooting from mobile punts, was identified as the most disturbing human activity in relation to staging waterfowl in this area. Similar results and conclusions were reached in another comparable study area. The results have implications for refuge designs and zoning of disturbing recreational activities.