Offshore windfarms are to be painted black in a bid to reduce the number of birds that die after flying into them.

The Department for Environment, Food and Rural Affairs has launched a four-year trial to paint the wind turbines after officials raised concerns that the government’s plan to increase turbine numbers in the North Sea could spell danger for seabirds. Limited research has been conducted on the number of birds killed this way, but estimates range from four to 18 per turbine per year.

Donald Trump, the US president who has signed an executive order pausing all wind energy projects and pushed for deregulation of the fossil fuel industry, has previously expressed concern over wind turbines’ impact on birds. In December he told UK prime minister Keir Starmer he was making a “very big mistake” by imposing a windfall tax on the North Sea oil and gas industry. He also told him to “get rid of windmills”.

News of the trial emerged just before Starmer’s visit to Washington to meet the president.

Trump has been raising concerns about wind turbines since 2011, when North Sea windfarms were first proposed in view of his golf course in Aberdeen.

A study in Norway which examined the effects of dyeing one wind turbine blade black found it resulted in a 70% fall in associated bird deaths.

Iberdrola, a Spanish utility company, has tried another direction by using decals that look like eyes at the base of the wind turbine. This tactic was tested at the Lourdes-Tarbes-Pyrénées airport in south-eastern France and was found to be successful at deterring birds. Iberdrola said the number of birds of prey seen around the airport dropped by 65%.