May 2007, the external radiating light sources on gasproduction platform L15, have been exchanged for a special made light source - low in spectral red. L15 is situated in the North Sea, about 20 km Northwest of the island Vlie land.
The environmental effectiveness has been determined during the bird autumn migration, between October 5 and 8, 2007. Dense flocks of song birds, wader birds and ducks were observed. Also some co-migrating owls were seen. Weather conditions, to assess the impact of the new lighting were extremely favourable: light fog and almost complete cloud cover.
The observed species and numbers were compared with assessments from previous years. Periods of comparable weather conditions were selected and the same observer was employed in order to assure full comparability of assessment techniques.
Based on this comparison it is concluded that 2-10 times less birds are negatively impacted (circling around the installation for a prolonged period of time) by the new light source as by the original standard white (tube lights) and orange (sodium high pressure lights) lighting. Also the number of birds actually landing on the platform was decreased.
The negative impact on birds therefore was significantly reduced.
For technical reasons, a limited number of light sources was not yet replaced during our observation period. The presented results are under estimating the effect if all external lights would have been replaced.
It is also concluded that a North Sea wide approach would be needed and that application of this new light source could reduce the number of impacted birds from about 6 million to less as 600.000.