The overall purpose of North Sea I is to undertake offshore surveys of birds, bats and marine mammals in areas of the North Sea. The project is divided into three work packages on, respectively, birds, bats and marine mammals.

The aims of the birds work package are to obtain information on bird abundance and distribution in the North Sea I investigation area. A combination of existing data and data collected during the programme will provide information on bird distribution, abundance and movement within and around the area. Effects on avian species by offshore wind turbines fall into two major categories:

• Birds either feeding or migrating in the vicinity of offshore wind farms may alter their distribution and/or behaviour in relation to the presence of the wind farm and/or collide with turbines or other structures associated with the development.
• Birds may show an immediate reaction to infrastructure developments in the form of spatial redistribution and/or collision mortality. These immediate effects may translate into long-term impact at population level.

The aims of the bats work package are:

• Identification of bat species potentially occurring in the study area, with special focus on scientific peer-reviewed publications addressing wind farm impacts on bats and knowledge of baseline conditions for bat populations relevant to the investigation area. This will include own data collected in the North Sea Energy Island surveys and data from other recent wind farm projects in the North Sea, if available.
• Passive acoustic monitoring of bats with ultrasound detectors within and around the project area on buoys and at land-based stations to identify potential bat migration routes in and near the project area.
• Identification of recorded bats to species or genus level, quantification of the temporal and spatial variation in bat abundance, seasonal counts and activity.
• Monitoring of background noise levels to quantify the detectability of bats with the acoustic detectors in the project area.

The aim of the marine mammals work package is to conduct a baseline investigation of marine mammals based on both field surveys and existing available information on their occurrence within and around the investigation area of North Sea I.

Furthermore, based on the obtained information, the project will include a description of the marine mammal species and their distribution and movements in the investigation area. This also includes descriptions of the migration routes of the marine mammals in and around the investigation area and their potential exposure to underwater noise and vibrations.