Familiar garden birds with unusual plumage features, such as a Blackbird or sparrow with striking white feathers, will often catch our eye, and the British Trust for Ornithology (BTO) is asking for help in mapping these scarce occurrences.

Each year BTO receives multiple calls and messages from members of the public who have spotted something a little out of the ordinary in their garden. These sightings often refer to a common bird, that doesn’t look quite right… a Starling with a white head? A sparrow with white wings? An all-white Magpie? A Robin without its distinctive red breast?

Many birds can show unexpected plumage abnormalities, and ornithologists are hoping to unravel some of the mysteries relating to these widespread phenomena.