Aarhus University Seal / Aarhus Universitets segl

No. 239: The number and distribution of moulting seaducks in Sejero Bay in relation to human disturbances

Petersen, I.K., Nielsen, R.D., Therkildsen, O.R. & Balsby, T.J.S. 2017. Fældende havdykænders antal og fordeling i Sejerøbugten i relation til menneskelige forstyrrelser. Aarhus Universitet, DCE – Nationalt Center for Miljø og Energi, 38 s. - Videnskabelig rapport fra DCE - Nationalt Center for Miljø og Energi nr. 239


This report describes the relationship between the geographical distribution of moulting seaducks and the level of human disturbances in the Sejerøbugt. The project was conducted in July and August 2014 and 2015. A total of six earial surveys of birds were conducted, using a high resolution digital camera. The density and distribution of birds was recorded from digital orthophotos. The level of human disturbances was recorded by use of a digital radar, situated on the northernmost point of the island of Nekselø. From radar data activities of boats and ships could continuously be monitored over a long time period. 

The investigations showed a negative relationship between Common Scoter density and the level of human disturbances, both when based on long-term and short-term disturbance data. No relationship was found between Common Eider density and the level neither of human disturbances, based on long-term nor on short-term disturbance data. There was insufficient data on density of Velvet Scoter and Red-breasted Merganser to perform the analysis. 

From the collected data on moulting Common Scoter density two core areas for the species could be identified.