A PROTECTED NERITIC
Grunnosen between Børilden and Store Stonga is a well protected marine area, with openings several places so that the circulation is good. Most of Grunnosen is less than 20 metres deep, not more than that most of the diving sea birds that we find in these parts can dive to the bottom to find food. The bottom many places is pure sand or mud. Each winter, this kind of bottom attracts species such as the White-winged Scoter and the Red-necked Grebe, even though they may be few in number.
Many of the Red-breasted Mergansers and Goldeneyes that over-winter in Austrheim can be found at Grunnosen. Grunnosen is especially important in periods of poor weather. Then, this protected area may also be a refuge area for other sea bird species.