They are a mainstay of the Scottish countryside, delighting people as they flit from branch to branch.

However, plastic pollution could be killing off the next generation of blue tits.

Scientists have discovered that blue tits in Glasgow are using 50 times more man-made litter to make their nests than their country cousins on the shores of Loch Lomond.

Research has found that chicks are less likely to survive when their early days are spent among detritus such as netting and fibres from tennis balls.