New York dims the lights to save migrating birds.

The state of New York is to turn off non-essential lights in state-run buildings to help birds navigate their migratory routes in spring and autumn.

Migrating birds are believed to use stars to navigate but they can be disorientated by electric lights, causing them to crash into buildings.

The phenomenon, known as "fatal light attraction", is estimated to kill up to one billion birds a year in the US.

Millions of birds migrate through New York along the Atlantic Flyway route.

Now those passing over the city by night will stand a better chance of making it further north.

New York Governor Andrew Cuomo said on Monday that bright outdoor lights will be turned off between 23:00 and dawn during peak migration seasons in spring and autumn.

The state will join several well-known New York landmarks that have already signed up to the National Audubon Society's Lights Out programme, including the Rockefeller Centre, Chrysler Building and Time Warner Centre.

Fatal light attraction appears to affect migratory songbirds such as warblers, thrushes and sparrows more than local birds, who learn where they can fly safely.

Daniel Klem, professor of ornithology and conservation biology at Muhlenberg College who pioneered the study of window strikes said the strikes were particularly worrying because the fittest members of the population were just as likely to die in this way as weaker birds.