Birds prefer their droppings to be on white cars, according to a scientific study. Student teacher Charles West, 37, carried out the survey for his department of education at Bristol University. He enlisted the help of 40 researchers and counted bird droppings on 2,000 motors reports The Sun. The team concluded that birds were less likely to dirty navy blue and black. Bird expert Dr Derek Toomer said they might "bomb" white cars because they associate the colour with predators. He added: "Birds do respond to colours.