As a Joint Venture between BioConsult SH, Justus Liebig University of Gießen, (Department Animal Ecology and Systematics, Research Group Behavioural Ecology and Ecophysiology) and DHI, the project follows the overall objective to fill the knowledge gaps regarding ecology of divers, e.g. habitat use and movement patterns within critical areas aiming to support conservation plans for this species as well as to improve conditions for developing conservation tools and actions for this species. Considering offshore windfarm developments, spatial distribution and temporal characteristics of habitat use of divers will be analyzed to set a sound basis for the relation of habitat loss due to offshore windfarms and habitat requirements of divers. Following knowledge gaps were identified:

• Little is known about habitat use and movements of divers within and between different wintering areas. It has been suggested that diver habitat choice varies in relation to tidal currents, other hydrological changes and direct weather impacts.
• Migration patterns and general movement schedules throughout the annual cycle of divers are largely unknown. Diver numbers fluctuate substantially in different wintering areas and intensive movements have been recorded along the coasts of the Baltic and North Sea. This indicates high mobility during the non-breeding period. As a result of the gap of knowledge about migration and local patterns, it has not been possible to understand and to evaluate the cumulative impacts of different human activities on these birds.
• Site fidelity to wintering and other staging areas is unknown. Whether birds are highly site faithful and return to the same places year after year or are flexible in using different geographic areas has important implications in evaluating potential impacts on populations.
• Locations of origin are unknown. During the non-breeding period divers are widely dispersed along the coasts and offshore areas in the Baltic and North Seas and northern Atlantic. Breeding populations are distributed across high latitudes of Russia, Scandinavian Peninsula, UK, Iceland and Greenland. Recoveries of ringed birds are scarce and therefore it is unknown which breeding populations are being affected on wintering and staging grounds.