Thousands of birds have been leaving their debris on the ships and the solar panels, threatening the only power source for lightships and turning the highly visible bright red of the boats into a cloudy shade of white.
Now, in a bid to repel the unwanted guest, bird-scaring equipment is being installed on two unmanned vessels which will mimic the distress calls of half a dozen birds known to be regular visitors. Scientists hope the dawn-to-dusk chorus will deter the birds from fouling the solar panels and the ships, delegates to an international conference on pest management at the University of Wales, Cardiff, were told.
Birds have always been something of a problem for Trinity House, the organisation responsible for lighthouses and buoys around the coast of Britain, but the trouble has been exacerbated by the arrival of unmanned and fully automatic lightships, two of which are now on station in the Wash and at South Goodwin off Dover.
Barry Rodwell, deputy principal development engineer with Trinity House Lighthouse Service, said: "We have hit a problem with birds fouling and it can be quite horrendous. We normally paint the ships red and they can get white all over in a very short time with the numbers of birds involved. These ships are painted red to act as a marker to shipping during the daytime and changing colour to white is not very helpful."
"And of course, if the solar panels get covered up, they would stop producing the necessary power for the various aids to navigation on board the vessels."
He added: "It was not a problem when they were diesel powered because they were visited for refuelling and maintenance, and once the ship was alongside it would hose the vessel down."
A bird-scaring system designed by Sussex-based Scarecrow Bio-Acoustic Systems will be used to keep the birds away. The company has digitised the distress sounds of a number of birds including the herring gull, blackheaded gull, common gull and lapwing, and installed them in a loudspeaker unit that will by set up on the ships.
A system has already proved its worth at the British Embassy in Rome after it was invaded by starlings.