Light-induced bird strikes on vessels in Southwest Greenland. Technical Report No. 84

Seabirds are highly visually oriented organisms and are known to become disorientated at night in the presence of artificial light, e.g., from 
lighthouses, oil platforms or vessels. Coastal and certain offshore waters 
of Southwest Greenland constitute internationally important wintering 
areas for seabirds and bird strikes are reported as a problem when vessels navigate in icy waters using powerful searchlight. In this study a selection of navy vessels, cargo vessels and trawlers reported on incidents 
of bird strikes using pre-supplied forms. 
Among 19 vessels initially included in the study, 10 vessels reported a 
total of 41 incidents of bird strikes over a period of two winters (Oct.-
Mar., 2006-08; for two vessels also the winter 08/09). Most bird strikes 
occurred less than 4 km from land (76% events, 93% birds), but in two 
cases as far offshore as 205 km and 422 km. The mean number of birds 
(±S.E.) reported killed was 11.5 ± 3.1 birds/incident, with 88 birds reported as the highest number. All bird strikes occurred between 4 p.m. 
and 5 a.m. and significantly more birds were killed when visibility was 
poor (snow) rather than moderate or good. The species reported were 
common eider (95%), king eider (3%), long-tailed duck (1%), murres 
(<1%) and black guillemot (<1%). In 17% of the incidents vessels reported about damaged navigation or communication equipment due to 
avian collisions. 
Despite huge variation in the reporting of bird strikes among vessels, 
this study confirms that light-induced bird strike incidents occur on a 
regular basis in Southwest Greenland during winter, especially in coastal 
areas when visibility is poor. A crude estimate for the annual number of 
birds killed in Southwest Greenland sum up to app. 2.000 individuals; 
however, additional studies are needed to verify the level of this estimate. It is clear though, that common eider is the main species of concern, accounting for 95% of the birds reported. 
To reduce the number of bird strike incidents I recommend vessels to 
avoid known high-risk areas at night when visibility is poor, to shield as 
much light as possible towards the sky, to switch off light when not used 
and I recommend studies that investigate alternative ice lookout techniques, e.g., filtering out certain wavelengths or combining modified 
search light with image enhancing technology.